HAWAII . GEOTHERMAL PROJECT...HAWAII . GEOTHERMAL PROJECT HGP-A RESERVOIR ENGINEERING " September...

:.' HAWAII . GEOTHERMAL PROJECT

HGP-A RESERVOIR ENGINEERING

" September 1978

by

Paul C.Yuen Bill H. Chen

Deane H. Kihara Arthur-S. Seki

Patrick K. Takahashi

SUPPORT FOR PROJECT PROVIDED BY:

Depar:t!llent of Energy, Contract EY-76-C-03-1093 Energy Research and Development Administration, Contract E(04-3)-1093

National Science Foundation,Grant GI 38319 ,~ta teo.f Hawaii, Grants RCUH 5774, 5784, 5942

County of Hawaii, Grant RCUH 5773· Hawaiian Electric Company, Grants 5809, 5828

University of Hawaii Holmes Hall 2062540 Dole Street

Honolulu, Hawaii 96822

..•. , .

.....

·ABSTRACT

The Hawaii Geothermal Project well HGP-A has undergone a two-year testing program which included cold water pumpdown tests, flashing flows with measurements of temperature and pressure profiles, and noise surveys. These tests and the data obtained are discussed in detail.

Whi Je .. th~ pumpdown tes ts conducted ri ght after the slotted 1 i ner had been installed and the mud removed indicated that the well had very poor permeability, HGP-A was flashed successfully on July 2, 1976. Maximum quiescent bottomho1e temperature following that initial flash was measured to be 358°C. Comparison of subsequent discharges shows that with each succeeding test, the flow rate has increased, possibly due to the displacement of dril1irig mud embedde~ in the wellbore surface. The flow rates range from a maximum of10lK1b/hr·atwe11head pressure of 51 psig to a throttled 76 K1b/hr at 375 psig wellhead pressure, with possible electrical power production of 3.0 to 3.5 MWe~

Temperature and pressure profiles taken during flow tests indicate that the fluid 'in the wellbore is a mixture of liquid and vapor at satur:ation conditions. The absence of a liquid level during flashing discharge confirms that flashing is occurring in the formation.

Pressure drawdown and buildup analyses yield a value of transmissibility (kh) of approximately 1000 millidarcy-feetwith a pressure drop across the apparently damaged skin of 500-600 psi.

'The pressure profiles taken during flashing flow consist roughly of three approximately constant gradient lines that intersect at the junction of the casing and the slotted liner, and at approximately 4300 feet depth, which leads to the conclusion that the major production zones are near bottomho1e and in the vicinity of 4300 feet. Furthermore, the data points on 'the log-log Horner type plot seem to fallon two different but consecutive straight-line approximations. This could be interpreted to be the result of two different production layers with different kh values.

ABSTRACT • . . .

LIST OF FIGURES .

LIST OF TABLES .

PRELIMINARY TESTS .

TABLE OF CONTENTS

. . . . . . . . . . SUMMARY OF PRODUCTION FLOH TESTS

Page

-i

. . iii

vi

1

17

November Flow Test (11/3/76 -'11/17/76) • • e, . . . . . .. 17 December Flow Test (12/12/76 - 12/19/76) .•. January/February Flow Test (1/26/77 - 2/11/76) March-May (3/28/77 - 5/9/77) . .'.

PRESSURE DRAWDOWN AND BUILDUP ANALYSES

1. Pressure Drawdown Analysis .. ' ...••

• ." jIJ

2. December Pressure Buildup Analysis .. . .••• 3. January-February Pressure Buildup Analyses ....••• 4. Reca 1 cul at; on of December Data . . • . • . . • • • 5. Di scussion • • • • .

. RESERVOIR RECOVERY ANALYSIS.

NOISE LEVEL REDUCTION .

SCALE DEPOSITION • e"·. •

SUMMARY . . . . . . . . -. . . . ." . CHRONOLOGY OF EVENTS 'AT H~P-A

PAPERS AND PUBL:ICATIONS . . • • •

ii

27 28 33

46

46 52 56 59 60

62

77

"S,O.,

84

87

94

LIST OF FIGURES

FIGURE 1 Chronology of Well Testing Events -

Page 2

2 Schemati c Diagram of Kuster Pressure Recorder 3

3 Schematic Diagram of Wireline System. . . • . 4

4 Temperature-Depth Plot for HGP~A with Drilling Mud in Borehole 5

5 Temperature-Depth Plot for HGP-A

6 Schematic Diagram of HGP-A Wellhead Instrumentation for Flow Test, July 22, 1976 .••.•••..•.•••

7

8

HGP-A Flow Test, 'July 22, 1976. 'Lip Pressure with Time . • • •

HGP-A Flow Test, July 22, 1976. Lip Temperature with Time

Variation in Wellhead &

Variation in Wellhead & . . ". . . . . . . . . .

9 Temperature vs Pressure for HGP-A, July 22, 1976, after

9

10

12

13

Four-Hour Discharge . . . • • • • • • . • • ••.• • . 14

10 Temperatur~ vs Depth for HGP-A follm'ling Four-Hour Discharge 15

11 Pressure vs Depth for HGP-A following Four-Hour Discharge 16

12 Hawaii Geothermal Project Flow Test Equipment and Instrumentation . . . • • • • • • •• • • . 18

13, Wellhead Pressure vs Time, November Flow Test . • • 19

14 Wellhead Temperature vs Time"November Flow Test

15 Lip Pressure vs Time, November Flow Test •..••

'16 Total Mass Flow Rate vs Time, November Flow Test.

17 Steam Flow Rate vs Time, November Flow Test •.

18

19

Enthalpy of Discharge vs Time, November Flow Test

Steam Quality vs Time, November Flow Test

20 Thermal Power vs Time, November Flow Test

. . . . ..

20

21

22

23

24

25

26

21 Temperature Profiles during Flashing, January/February Flow Test 30

22 Pressure Profiles during Flashing, January/February Flow Test 31

iii

."!.

LIST OF FIGURES (Continued)

FIGURE 23 Temperature Recovery after January/February Flow Test

24 Wellhead Pressure during March-May Flow Test •

25

26

Well he;ad Temperature during March-May Flow Test • ,: .•.. ,

lip Pres'sure during March..:May" Flow Test .••••

27 Total Mass Flow Rate during March-May Flow Test .

28 Steam Flow Rate during r1arch-~ay Flow Test .. ....

29 Enthalpy of Di scharge dur~ng March-~1ay Flow Test

30 Steam Quality during March-May Flow Test .•.

31 Thermal Power Output during March-May Flo~ Test

32 Temperature Profiles during March-May Flow Test

33

34

Pressure Profiles during March-May Flow Test

Log-Log Plot of November Discharge Test Data

. . ..

Page

32

34

35

36

37

~~8

:-39

40

41

43

44

47

35 Semi-Log Plot of November Discharge Test Data. 48

36 Linear Plot of I~itial Data for·November Discharge Test. 49

37 Log-Log Plot of December Pressure Buildup Test Data. 54

38 Semi-Log,Plot of December Pressure Buildup Test Data 55

39 Semi-Log Plot of January Pressure Buildup Test Data • .• 57

40 Semi-Log Plot of December Pressure Buildup Test Data 58

41

42

43

44

45

46

,Water Level Recovery Rates . . Water Level Recovery Rates (l~i th Common Point of Zero Depth)

Temperature Recovery following July Flow Test •.•

Temperature Recovery following November Flow Test.

Temper:-ature Recovery follm'ling December Flow Test

Temperature Recovery following January/February Flow Test

iv

.63

64

. 66 & 67

68

69

70 & 71

LIST OF FIGURES (Continued)

FIGURE 47

48

Temperature Recovery following March-May Flow Test

Pressure Recovery following March-May Flow Test ••

49 Temperature Recovery following March~May Flow Test.

50 Pressure Recovery following March-May Flow Test

51 Noise Levels during July 22, 1976 Flow Test •••

52 . Hawaii Geothermal Project. Flow Test Equipment and Instrumentati on with Muffl er • • • • • • • ••

53 Map Showing Sites for Noise Level Readings

.-

• it • •

'. ... .

. . . '.

Page.

73

74

75

76

78

81

82

TABLE 1

2

3

LIST OF TABLES

Mud Loss from Initial Completion of Hole •.

Summary of Pumpdown Test . • • .

Throttled Flow Data 1/26/77 - 2/10/77

. . . ~ . . .

4 Projecticns Obtained by Extending Data Plots of March-May

.' .

Page 6.

7

29

Flow Test ............. ,. . . . . . . . . . 42

5 Comparison of Discharge Tests at 25 Hours after Initiation of F10\'/ • • ~ • • • • • ~ • e * eo ~ • = • • ~

6 Comparison of Pressure Drawdown and Buildup Tests

7 Summary r.f ~/a ter Leve 1 Recovery • • •

8

9

Permissible Exposures - Noise Level

Recorded Noise Level, July 19,1976

10 Noise Level Readings on DBA Scale .

. . . . . . . . . . .

11 Summary of Preliminary Test Results and Analyses

45

61

65

77

79

83

86

PRELIMINARY TESTS

On-site testing of the well began upon initial completion of HGP-A with

logging by Gearhart-Owen electronic equipment to obtain standard E, resistivity,

gamma ray, two arm caliper, temperature, and cement bond logs. However,the

downhole temperatures were found to exceed the temperature tolerance of the

cable insulation which is 150°C. Subsequently, Kuster mechanical subsurface

temperature and pressure recorders were used to measure downhole conditions.

A chronology of events is given in the Appendix and summarized graphically in

Figure 1. Figure 2 is a schematic diagram of the Kuster pressure recording

assembly, which is 66 inches long and 1-1/4 inch in diameter. Its upper

temperature limit is 370°C. Figure 3 is a schematic dia'gram of the wireline

system used to position the instrument packages in the wellbore. The

temperatur.e and/or pressure recorder is hooked onto a 0.08211 stainless steel

wire and placed in the lubricator, a device which allows operation of the

measurement equipment during flashing. The lubricator is constructed of , '

aluminum and is rated at a pressure of 4,000 psi. The wireline is raised and

lowered using a winch,run by a gasoline engine. A depth indicator is part

of the entire system.

The temperature profiles measured after the termination of mud circulation

upon completion of drilling is shown in Figure 4. All of these profiles were

taken with mud in the borehole. The maximum depth of the initial profile

taken on April 28 was 1 i mi ted by the 1 ength of th,e 3/411 cab 1 e wh i ch was used

to lower the instrument assembly. It waS feared that the 0.082" stainless

steel wire would not be strong enough to pull the assembly up in the event

that a cave-in or obstruction of some sort occurred, as the slotted liner had

" ,"

.' , ,,'

, ", .. " . .. . "

,"." "

, '

, . "

""'" .. 1976 1977 I

"

A M J J A S 0 N D J F M A M 'J J A "

WELL STATUS Airlifting -- • Preliminary Flow and Tests • - •• •• • -Throttled Flow Test .. --Production Flow Tests • - -

ACTIVITY Pressure Dra\'/down Measurements -Pressure Buildup Measurements 4L 1-- - • -Temperature Profile Measurements . ,. ..... _. ••• .. •• ~ . • • ~ . • ... • • f- • • • • • •• .. . •• Pressure Profile Measurements • • . ... .. • .. .. • • • •• • • • ~ ... • • • •

I Water Level Measurements ... c:w. iii - - .. ~- .. • ~-i

Downhole Water Sampling - • • .. • ... •

,

Figure 1. Chronology of 14ell Testing Events

" ,

I "

.... ,-..

WIRE LINE -f-SOCKET

CLOCK

LEAD SCREW

CHART CARRIER

STYLUS ASSEMBLY-+~

STYLUS SHAFT ---r-..::..a

BOURDON TUBE--f~~

BELLO~IS -I~~

.•. - .-~ - ... _.-

Figure 2. Schematic Diagram of Kuster Pressure Recorder

-3-

.' ....

,,-,-

,

-4- , .

.... w w

u... z -:I: .... 0... UJ

C

. Temperature in °C

50 100 150 200 250 300 350

--- 4':'28-76 15 hours

----- . 5-1-76 . 3 days .

1000 I----i~ -- 5-4-76 6 days 5-11 - 76 13 days

5-20-76 22 days 500

20001~----~----~----~----~----~----~----~

3000

'. . Boiling poin~ curve _ U)

'Q) -.(1)

", . . . , ' "

1000 '~

4000

5000~----~----~----~~--~----~----4-~~~1500 .:- .)

,

6000~~~~----~----+-----~----~----~--~~

c .. -J:. et-a. Q)

o

~ __ ~~~~~f_w~e~I~1 --~----~----~~----~~~~2000 ,

Figure 4. Temperature-Depth Plot for HGP-A with Drilling Mud in Borehole

-5-

, ,

not been' installed yet. For the profiles taken after April 28, the ma~imum

depths at which temperatures were measured give an indication of the rate at

which mud caking occurred. The daily mud loss record is shown in Table 1:

TABLE 1

MUD LOSS FROM INITIAL COMPLETION OF HOLE

Date

April 30 May 1

2 3 4 5 6 7 8 "9

10 11 12 13 14 15 16 17 18

Mud Loss Down Well* in feet/day

300 286 184 186 174' 170 146 107 84 67 61 55 49 49 39 37 38 30 30

*Mud was added each morning to bring well to approximately the same level.

-6-

Following installation of the slotted liner, washing the mud out. of the

borehole was completed at 8:30 PM on June 5. A pump down test in which surface

water was pumped into the borehole was conducted on June 6 and 7. A summary

of this test is given in Table 2:

TABLE 2

SUMMARY OF PUMP DOWN TEST

Date GPM Time of Flow (minutes) Volume (gal) Back Pressure (Esig)

June 6 340 46 15,640 700+

June 6 108 105 11,340 500+

June 6 108 60 6,480 500+

June 6 200 55 11 ,000 600+

June 6 300 70 21,000 700+ . 750+ June 6 530 10 5,300

June 6 630 7 4,410 800+

June 6 300 8 2,400 700+

June 6 200 5 1,000 600+

June 6 100 6 600 500+ . June 7 300 3 900

June 7 100 180 18,000 300

TOTAL: 98,070 gal

For comparison purposes, the rise in back pressure as the flow rate is increased

to 300 gpm can be used as a rough indicator of penneabi1ity as follows:

20 psi or less = high permeability ,

up to 75 psi = moderate permeability

more than 150 psi = very poor permeability (non-producing well).

However, external factors such as the caki ng of dri 11.i ng mud coul d produce erro

neous results.

-7-

Temperature profiles measured before, during, 'and after the pump. down

tests are shown.in Figure 5. The curve labelled 1 was taken 12-1/2 hours

after washing out the mud but before the pump down tests were. started. ; Curves

2 and 3 were taken 17 hours and 36 hours after washing, between runs of the

pump down tests. Following completion of the pump down tests, three temperature

profiles were. taken. These, labelled cur~es 4, 5, and 6, were measured 27-1/2

hours, 4 days, and 8 days, respectively; after completion of the pump down

tests. Temperature recovery and further heating of the wellbore fluid is

seen to be quite rapid.

Air lifting was used to artifically induce the well to flash. Inair

lifting, air is injected 'into the water column, thereby displacing SOmE! of

the liquid, and causing the liquid . level in the we11bore to rise, eventually

reaching the surface. As liquid flows out of the we11bore, hotter liquid ~ . .'

from deeper in the. well rises ,and if the condi ti on.s are ri ght, the temperature , .

of the fluid exceeds the boiling point temperature at that pressure, causing

the liquid to flash into vapor.

On June 22-24, airlifting was attempted, ustngtwo 100 psi, 17Scfm air

comPressors. However, this attempt failed when. a 250 foot length of air hose

was lost in. the well •.. A second attempt on· July 2 was successful. and HGP~A was

flashed for approximately four minutes.

On July 19, the well was flashed for 50 minutes, on July 21 for 30

seconds to check instrumentation,.and then for a longer period of four' hours

on July 22 to obtain preliminary values for wellhead pressure and temperature,

and total mass flow rate.

The four hour well f1 ash i ng on July 22 was accomp 1; shed us ing the well head '.-

instrumentation shown in Figure 6. The sonic flow, lip pressure method of

-8-

... :C ' J0-

o o 50 - I EMPERATURE, °c

100 150 200 250 300 350 --,

CD <:> 6-6-76 J 12 1/2 HRSAFTER MUD WASHED OUT

, ® e----~--- 6-6-76 J 17 HRS AFTER FIRST PUMPDOWN TEST _ '

,1000t-1 ---+---1----04-'G) ' ~ 6-7 -76.1 36 HRS AFTER FIRST PUMPDOWN TEST

CD 8---- 6-8-76" 27 1/2 HRS -AFTER SECOND PUMPDOWN TEST

® 0···· ·· .. ·· .. · .. ···6-11-76.1 4 DAYS ' AFTER SECOND PUMPDOWN TEST

® ~ : 6-15-76 .. 8 DAYS AFTER SECOND PUMPDOWN TEST "

200011 I· a.

.... . . I

n. ~ I - 1 ~ , J --ae: ' I -'e~ I w 40001 'e ..... _~ ' I ' ..... ~ o '

50001 ' I'qq · rrl :' f I

60001 ' I · '., I ·" .. I I "Y.;:;;IM , '.;;~ I

Figure 5. Temperature-Depth Plot for HGP-A . · "

7000' . I

-6" DISCHARGE TUBE

LIP TEMPERATURE-

10" VERTICAL VALVE--

TEE---

10" MAIN VALVE---

LIP PRESSURE

10" HORIZONTAL VALVE • • •• - ~ ' .' • • '. p. "

a" DISCHARGE TUBE

, , .

2" VALVE

Figure 6 .

WELLHEAD PRESSURE a TEMPERATURE

BLEED LINE

SCHEMATIC DIAGRAf1 OF HGP-A HELLHEAD INSTRUMENTATION

FOR FLOW TEST J JULY 22J 1976

-10-

- - ---------

James1 was used to obtain total mass flow rate with lip pressure being measured

at the end of a vertical 6" discharge tube. In addition, an 8" discharge tube

mounted horizontally was also flowed for a brief time. Wellhead pressure

and temperature were obtained from a bleedline controlled by a 2" valve.

Results of the four-hour flashing are shown in Figures 7 and 8 which

give wellhead and lip pressure, and wellhe'ad and lip temperature, respectively.

The lip pressure at the end of four hours was 23 psig, which corresponds to

a mass flow rate of about 166,000 lbs per hour, assuming a specific enthalpy

of 800 BTU/1bm.

Figure 9 shows a plot of temperature vetsus pressure for HGP-A a few

hours after the four-hour flashing on July 22. The number adjacent to each

data point represents the depth at which that data point was taken. Also on

the figure is the boiling point for pu~e water. At the time that the data

were taken the we11bore contained a saturated mixture of liquid and vapor

from a depth of 1000 feet to 4600 feet.

.:. Ftgures 10 and 11 are plots of temperature and pressure versus, 'depth

for HGP-A for the indicated times after the flashing on July 22, 1976. As

shown in Figure 10, t~e temperature profile obtained one week after th~

flashing was fairly close to equilibrium, except that the,port,ion of the w~ll,.·

that is cased is continuing to decrease slowly in temperature. The temperature

profiles also appear to indicate the the major production regions are probably

between 3,500 and 4,500 feet and around 6,000 feet.

1 James, Russell, "Measurement of Steam-Water Mixtures Discha~ging at the Speed of Sound to the Atmosphere", New Zealand Engineering, pp. 437-441, October 1966.

-11-

..... .. ' ~ .. ,:' ~" .

-0

N I

o -en Q.

500

300

200 HORIZON1:AL VALVE OPENED FOR FOUR -MINUTES'

100 WELLHEAD PRESSURE

LIP PRESSURE

O~I--------~------------------------~----------~------------~----------~---------~------------o

. "

.2 TIME, HRS

:3

Figure 7. HGP-A Flow Test,Ju1y 22, 1976. Variation in Wellhead & Lip Pressur.e with Time •

4

..

-' W I

IJ.. o .. W

450r \ ,

4 ';,";"

0: 300 ::>

~ 0: W · a.. :: 250. w ...

200

150

WELLHEAD TEMPERATURE

HORIZONTAL VALVE OPENED FOR · FOUR MINUTES

'.

\,

LIP TEMPERATURE

lOa' I I . : I

o 2 3 4 "

TIME, HRS

Figure 8. HGP-A Flow Test, July 22, 1976. Variation in Wellhead & Lip Temperature with Time.

[ .

..

50 -o '-

25

50

~ 100 ::> (J). 00 W 0::: a. 125

150

175

• • ... 100 •• ~ ,"

100

. ~' .. ~ . ,-

TEMPERATURE,OC 150 200 250 . -300 350

500 G __ ---- --

Figure 9

~ 1000

1500

• 3800 q 40000

\ - 4300 0

\ 4600

4900 < 5200 0

. , 550g.. •

."" 58000 .....

\ . . 6100 $....,. ......

- ...... - ............

6400

TEfv1PERATURE vs PRESSURE FOR HGP-A

July 22, 1976 AfferFour- Hour Discharge

-14-

-(J1 I

250 300

10001 e 18 ;~

20001 . ·e·;~n~.",..._ I I. "'

~ 30001 . I ' I ' I . ~ & I w tJ... .. :c: .... a... w 4000 .. -

.0

A 7-22~76 ' ......---- 7-29-76 s-------- 8-'4-76 <:)0 •••••••••••••••• , 9-2-76

\.

50001 y;~ l'

6000

, Figure 10

TEMP'ERATURE vs DEPTH FOR HGP-A

FOLLOWING FOUR-HOUR DISCHA~GE

7000' "

350 ---.

PRESSURE, kg/cm2 ( I .

o ~ 2~ 5? 7~ Iqo 1~5 I~O . 1~5

10001 WI

20001 · 8 ltl

t:i 30001 . I ~ I 1"t ~ W 0\ U. I .. .:r:

I-- . 0.. ~ 4000/. .

A . .. 7-22-76 .~----. 7';'29-76

. ro-:.------ ·8~4~ 76 ,.

50001 :-),

6000

Figure 11

PRESSURE vs DEPTH FOR HGP-A

FOllOWING FOUR-HOUR DISCHARGE

7000' I ----..L...---,-____ -...1-__ ...;...L-___ -'-__ -J.. __ ---J

SUMMARY OF PRODUCTION FLOW TESTS

November Flow Test (11/3/76 - 11/17/76)

Following the installation of the silencer/separator unit (Figure 12),

which basically provides for some fluid discharge noise silencing, separation

of steam and water, and measurement of total mass flow and liquid flow, a :':'.;:.""".'

two-week discharge was run to test the equipment and also to determine

whether the well would produce for that length of time. Test data on. well

performance were recorded and are plotted in Figures 13 to 15, which give

wellhead pressure, wellhead temperature, and lip pressure as functions of

time. As shown, following an initial transient flow during which the

wellbore was discharged, the pressures settled into an expected straight

line variation on the semi-log plot. The water flow as measured by the

height of the water flowing over the weir notch remained essentially constant

at 24,000 pounds per hour throughout, except for the initial period.

Figure 16 is a plot of total mass flow rate as derived using the Russell

James method. At the end Of the two-week period, total mass flow rate was

74~OOO pounas per hour~ Figures 17 to 20 give steam flow rate, enthalpy,

steam quality, alia thermal power as function of time.

-17=

--co I

Figure 12

HAWAII GEOTHERMAL PROJECT

flOW TESTEQUtPMENT AND INSTRUMENTATION

SEPARATOR AND SILENCER STACKS

H)WATER HEIGHT

WIRE LINE DOWNHOLE

GAGES AND SAMPLER

. " 6" DISCHARGE

IN WEIR \.irJLIQUID FLOW I~'.>! RATE)

TO TWIN CYCLONE SAMPLER

" CONTROL VALVE

""'MASTER VALVE

TUBE

LI PPRESSURE· (TOTAL "MASS FLOW RATE)

o ' d

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o ----- ---- ,-- -- -- ----~- --------

, 0.01 , 0.1 1.0 to.O 100.0 IOOO~O TIMEt, HOURS

" ", L

Figure 17. Steam Flow Rate vs. Time. November Flow Test.

·· 0 ~----~----~~-----'-------r------r---~~------~ d o

o -

L-~--~~----~~----~------.~----~~----~~----~~ o 0 0 0 0 o 0 0 0 = 0 m m -

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0 0 -

-d

5 o~-----o~-----o~----~o------~od o m w ~ w - 0/0 IA.LtlvnO V'J'V3.LS

-25-

(J) ~ ::> 0 :c .. W :E -l-

0

+oJ en OJ t-3 0 r-LL.

s.. , OJ . '

.: :..0 , E OJ > 0 z:

0

OJ E ..... t-. en >

~ ..... r-res ;:, 0-

E ttl OJ

+oJ en

0

0\ r-

OJ s.. ::s en ..-

LL.

0 0 ' 0 o. -

t t

• ~ 4~ 0 .

0 0 -

I~ · t. +' U)

• • · GJ ~

t 3: 0 -LL.

4. s.. OJ

q .0 E OJ a > - · 0 z:

~ · OJ

t E or-

(/) ~ I

0:: · 4 U)

I ::l > 0 s.. :c OJ

<~ 0

q .. 0-

t ,··· - w -:2: I'd E - S-

I- OJ .c ~

· 0 N

OJ s.. ::s Cl

or-LL. .

-~ -d

-o ~--------------~--------------~------------~d o 0 a 0

. ~ 2 0

MW CB3MOd 1'VV~H3H.L

~26-

• 'a,." •

December Flow Test (12/12/76 - 12/19/76)

The main purpose of this flow test was to obtain temperature and pressure,

profile measurements while the well was discharging. While retrieving the

probe from the wellhead, the wireline was cut accidentally and the probe was

lost downhole.

'While rental recorder instruments were being delivered to the site, the

flow was throttled with the horizontal ,valve to a lip pressure measurement of

about 4psig. The wellhead pressure and wellhead temperature rose and leveled ,. ." ..

off from '46psig and '145°C to 181 psigand 194°C, respectively, with little

change in the total mass fl~w rate.

With the arrival of the instruments, temperature and pressure measurements

were made downhole, with the well flashing. A check'of the data showed that

the temperature at wellhead measured by the Kuster temperature probe within

the well head matched that measured by the temperature gauge mounted externally.

However, there was a discrepancy betwe~n pressures measured by the Kuster

probe located internally and the dial gauge mounted externally. A careful

check of the Kuster pressure probe revealed the possibility of a partial leak

of vapor into the outer portion of the bourdon tubes. Following this experience,

extra precautions have been taken with all gaskets, O-rings, and screw thread

lubricants and sealants.

-27-

January/February Flow Test (l/26/77 - 2/11 /77) ",

A series of tests to determine HGP-A output parameters under throttled

flow conditions was completed during this test period. Throttling was

accomplished by placing orifice plates of various sizes in the 8-inch diameter

section of the discharge line .. The results are summarized in Table 3.

There is a substantial increase in wellhead pressure from 51 to 375 psig as

the flow rate was reduced from 101 Klb/hr (100%) to 76 Klb/hr (75%) . ...

The electrical power output possible from these flow conditions was

calculated, assuming a conversion efficiency of 75% as the steam expands from . .

well head pressure to a. back pressure ·of four inches of mercury. There is a ..•

broad power output maxi Ilium of 3.5 to 3. 1 MW( e) over the range of we 11 head

pressur~from 100 to 300 psig. This range will allo~ a wide latitude in the

design of a wellhead generator system. While more power can be extracted per

pound of higher pressure system, this· advantage must be balanced against the .

more expensive equipment (pipe, valves, separator) that higher pressure systems

require.

Temperature and pressure profiles in the wellbore taken during the

throttled flow test are shown inFigures2l.and 22. As in previous flow

tests, these profiles indicate that the fluid in the welibore is at saturation

conditions with a mixture of water and steam flowing up through the wellhead.

As expected when the smaller orifice plates are in,the temperature and pressure

both increase in the wellbore.

Temperature recovery of the well after shut-in is depicted in Figure 23.

This figure shows temperature profiles (a) while the well is discharging at

76K1b/hr one day prior to shut-in, (b) 8 days after shut-in, (c) 14 days

after shut-in, and (d) 25 days after shut-in. The region below 3000 feet . depth shows a warming trend after being shut-in, with the exception of the

anomalous point at 4300 feet, while the upper region shows an initial cooling

period followed by warming.

-?R-

TABLE 3

THROTTLED FLOW DATA 1/26/77 - 2/10/77

STEAM STEAM POSSIBLE

O~IFICE ~OTAL'~ASS ~ELLHEAD .tITLLH~AD pELECTRICAL IZE tOW ATE FIoN ~ATE QUALITY ·RESSU~E EMP. OWER OUTPUT (INCHES) .J.KLB/uR) KLB ijR) (%) (PSIG (OF) (MWE}

8 101 64 64 51 295 3.3

6 99 65 66 54 300 3.4 I 4 93 57 64 100 338 3.5 N \0 I

3 89 54 '. '. 60 165 372 3.5

.... ~ ,

2-1/2 84 . ~8 57 237 401 3.3 \.

2 81 ~3 53 .293 419 3.1

. 1-~/4 76 39 52 375 439 . 3.0

4/07/77

1000

2000

-; 3000 {f. c: .-.c -g4000

5000

6000

7000

. ~ --:" .. .

Temperature in °c 50 100 150

~ -= 200 ' or:: 250 "\ 1 l

, . , ~, ~ • ~

~

.. [

\ ' '

~ L

1\ 1 \

... ~'\ \ ' -,

~

[ ~

~

,~ I[ ~

tl,

~ j ~

" ~ . 1 $ h. ... tJ.

. . -~ . . .\ ~ ..

------ Bottom of well .. '

• <!l

• 13

I I , ..

I I 1

100 200 ., ~oo 400 500

Temperature In OF

• 8" Wide Open 70 Klb/HrSfeam ® 4" Orifice Plate 66 • 21" 2

.. .. 58 eJ 1~1I

4 .. .. 50

Figure 21. Temperature Profiles During Flashing January/February Flow Test

300 350

- 500

' "

e Q) -Q)

- 1000 :: ' .5 .c -fit , C

, .

·-1 500

.- 2000 t

c,

600

Pressurem Psig o 100 200 300 400 500 600 700 800

o ~-'--~------~----~--~~~-----'-------r------r------'

1000 ~--~~----+--*--~-----ffi-----+----~--~--r---~

2000 ~--~~----+---~~----~~~-+----~------r---~

-CD

If 3000

\ c .-..c -g4000 \ •

5000 ~----~----~~--4------H~--~-----4--~--~--~

\ .6000 ~--+---+--+-~+---~_\----""'---+--------+-~--i

------ Bottom of well

7000----~~----~----------~------~----~----~----~

•• ---.. 8" Wide Open · @--@4"OrificePlate ... -__ 2 ~" II II

E!l 1~1I II II · 4

70 Klb/Hr Steam 66 58 50

Figure 22. Pressure Profiles During Flashing January/February Flow Test

-31-

---- ~----------~---------------------------------------------------

'- .' '1

Temperatura In °C

50 100 150 200 250· 300 350

~.

500 2000~----~----~~~~=---~----~r-----+-----~

CI) 'Q)

~ 3000~-----+------+-----~-t~~-r'~~~T-----~------~ .~ If 1000:: c -.s= -~4000~----~------r-----~~----r---~~r----~~-----4 5000~----+-----~-----+----~------~~~+-----~1500

I ~---- Bottom of well

7000~--~~--~~--~~--~~--~~--~~--~ 100 200 300 400 500. 600

Temperature In OF

e 2/10177 Well Discharging \,/ith 1 3/4" Orifice Plate

Q 0 2119/77 8 Days after Shut-in.

6----A 2/25/77 14 Days after Shut-in

• • 3/8177 25 Days after Shut-in

Figure 23. Temperature Recovery after January/February Flow Test

-32-

c -.s::: -0. Cl)

C

March-May (3/28/77 - 5/9/77)

In order to clean the wellbore of mud, cuttings, and debris, the well was.

surged once a day, for one hour, beginning March 21, 1977 to March 28, 1977.

Then the well was flashed for 25 hours with the discharge line fully open.

Following this, a three-inch orifice plate was inserted into the discharge

line and the well flowed for 42 days before being shut in. Figures 24 to 31

display the data obtained during this production test. If the data points

from this test are expanded linearly on the plots of Figures 24 to 3l,

then the projections given in Table 4 result.

During the flashing, detailed temperature and pressure profiles were

taken at 100 foot intervals along the wellbore. This information is presented

in Figures 32 and 33. As expected temperature and pressure decreased with

time decreasing total mass flow rate.

Table 5 presents a comparison of parameters for each flow test after

25 hours of discharge. Flow rates have increased steadily with each test as

evidenced by a 37% increase in total mass flow rate and 25% increase in steam

flow rate between the November and March test periods.

Because several complaints were received of the hydrogen sulfide odor

and its possible adverse health effects, an anemometer to monitor the wind's

speed and direction was placed at the wellsite. A questionnaire was.distributed

to nearby residents asking for dates, times, and severity of odor. In

addition, water samples were obtained at the wel1site and homesites downwind

of the site to ch-eck the hydrogen sulfide and sulfuric acid concentrations.

Of 34 residents, only five responded with reactions ranging from no discomfort

(only unpleasant odor) to nausea and burning feeling in the eyes.

-33-

March 28 to May 9, 1977

I I I >.t - I '" Ii> 8" open 300 I A .t. 3" orifice . •

200 c-

o-

K!. .. I

Q) ~

<.oJ ~

:l I

(f) (/) C!.) ~

0-

I 100

0 1 111111 1111111 I lilli' 111111 IlItll

0.01 0.1 I 10

Time, Hr .

. Fi gure.24. Well head Pressure during March-May Flow Test

March 28 to May 9,1977

I· '" '" aI' open 300 t A> &. 3" orifice

0 2.00 0 .. CD "-. ::J - ~ ~ - - - • - !.: •• fll 0 '-Q)

a.. I E w

{E. e,..'1 I

100

\.

0' !"" ,.," "111 11'" III"

0.01 0.1 10 100 '1000 .

Tima , Hr ..

Figure 25. ~Iell head Temperature during March- May Flow Test


120 I 1\ ~ . a" ® 0. open

A 0.. 3" orifice,

0' ""! "'" II II! 11111 ""! 0.01 ,;: 0.1 10 100 . IOod '

Time, Hr ',:;1-: ,.

Figure 26. Lip Pressure during March-May Flow Test


· I ~ ® '" a" open . 300 I .t. £ 3" orificil

to. .c "'-:9 200 ~

A

<1> -0 a::

I 3: w ......, 0 I lL.

100

I r \.

o 10 100

Time, Hr

Figure :~7. Total Mass Flow Rate during March-May Flow Test

".: March 28 to May 9, 1977

I Col Col 8 open .. 300 I 1 I> .. 3" orifice

'-:t: 200 " .0 32

(1) -I 0 W t.-eo I 3:

0 lL.

100

o I I I J ! ! ! I I I I I , , , ! II I I I I I I I II I I J

0.01 . 0.1 10 100 ' lOOO .

TIme t Hr

Figure 28. Steam Flow Rate during March";May Flow Test

>

I I

W \0 I

.a ..J ":l .CD

1200 I I II I I I ' I . . I I I I II I . I ·1 i· I I Iii iii Ii I I I I I , I ! March 28 to May 9 t 1977

., (!j ® 8 open 4. £ 3" orifice

IOOOI~--~----~----------+---------~--------~~------~

800 I .' 1 dr I -} .. 1: I ff l") I , . ~- .

6001 .1 ~ . . I

0.01

Time ,Hr--

-Figure 29. Enthalpy of Discharge during March-May Flow Test

,,'

I ~ o I

(/.

March 2a to May 9. 1977

901 ' . I all

@ @ open 311 'f' & £ on Ice,

I \ 'I ~ ~ 'I 70 ,~ ~ l~( X ~. ,;

50 1 ~ , ;:l.

, :;~

30' 0' , , , I , , , , , I , I J I J I I I I I I I , 1 I I ~

0.01 0.1 10 100 1000' .

Tlma t Hr '

Fiflure 30. Steam Qual ity during March-May Flow Test

, ~

--,

:: :E

140 Iii iii iii iii iii , iii.

March 28 to May 9 I 1977

II (e) (e) 8 open

3 11 °fo ~. ~ on Ice

100 I "

.','

60 I J!Jd' I·.

201 I~' ~ .~~

o I I I 'iii iii iii iii i I I J ii' i 'i I , 1·/1 J

0.01 0.1 10 100 '1000·

Trme I Hr

Figure ~n. Thermal Power Output during March-May Flow Test

Table 4

Projections Obtained by Extending Data Plots of March-May Flow Test

Well head Total Mass Steam Steam' . Electrical Time Pressure Flow Rate Flow Rate Enthalpy Quality 'Power

(Years) (psig) (Kl b/hr) (Klb/hr) {BTUIl b} (%) (r4l4)

1 153 81 59 900 73".7 3.2 ' ""

15 142 78 58 . 904 73.8 3.0

30 140 77 57 906 73.8 3.0

100 137 76' 56 908 73.8 2.9

......

-42-

Temperature 1 °C

180 200 220 240 o --~~~~--~----~--~~------r-----~----~

1000 ~----~~--~----~----~----r-----r---~

2000 ~----~--~~~------+-----~----~~----~-----1

.. ~ 3000 ~----4------+~~~~-----r----~--~~+-----~ .c _. 0. (1)

o 4000 k-----+-----+---~~~--~----_+----~----~

. 5000 ~----~~--+-----+-~~~+-----~----~----~ ..

6000

3 11 orifice prate in

® 04-5-77

£ 4-12-77

l!l l!l 4-19 -77 7000 L-____ ~ ____ ~ ____ ~ ____ ~ ____ ~ ____ ~ ____ ~

Figure 32. Temperature Profiles during March-May Flow Test

-43-

Pressure t kg/cm2

10 15 20 25 o ----~~--------------~----~------~------~----~

1000 J---___ ~,---+_--_+_,---_+_--__f___.--_I_--___:_i

2000 · . -

.,., . .. 't-I- 3000

t G)

D

4000

5000 3 n orifice plate in . -.~'" ~ 4";5-77 204 kg/cm2 pressure gauge ·0 e

. £ . ~ 4-12-77 105 kg/cm2 pressure gauge . 6000 a----m 4-19-77 · " .. II · 11

... ---e. 4-27-77 II II " .H

7000 ----"'----..1..----'-----""'---""""-----'-----'

PRESSURE" PSIG

Figure 33. Pressure Profiles during March-~1ay Flow Test ~ ; " " " ...

' :"-: :~( .

-44-

TABLE 5 ".

~. COMPARISON OF DISCHARGE TESTS AT 25 HOURS AFTER INITIATION' OF FLOW

':'.:

:. NOYEMBe;R. DECEMBE.B, JANUARY MARCH

~/ELLHEAD PRESSURE (PS IG) . 47 53 . 59 59 WELLHEAD TEMPERATURE (OC) . 146 . 150 151 153 LIP PRESSURE (PSIG) 7~9 10.1 12.5 13.9 WEIR HEIGHT (INCHES) . 3-1/2 4 4-1/8 4-3/16

I .po

WEIR TEMPERATURE (OF) '203 205 205 203 U1 I

MASS FLOW RATE (KLB/HR) . 87.9 103.4 • 114.3 120.4 LIQUID FLOW RATE (KLB/HR) ; .-;' 27.9 .39.5 . 42.5 45.2 STEAM FLOW RATE (KLB/HR) 60.0 63.9 71.8- 75.2

..

STEAM QUALITY (%) 68 62 63 . 62 ENTHALPY (BTU/LB) 888 833 845 842 THERMAL POWER (Mw) . 22.9 25.2 28.3 29.7

5/13/77 ... ~~

(

PRESSURE DRAWDOWN AND BUILDUP ANALYSES

While data sufficient to assess a producible geothermal field can be

obtained only frOTa a number of properly-spaced wells, some limited reservoir

information can be obtained from a single geothermal well by utilizing the

theory developed for oil and gas fields. However, caution is needed in using

these results because of several reasons, including the fact that the theory

is basically one for single-phase flow and HGP-A produces two-phase flow. A

summary of the basic theory and referen~es is given in HGP Engineering Tech

nical Memorandum No.2, Geothermal Reservoir and Well Test Analysis: A

Literature Survey" 1974, by B. H. Chen.

During the b/o-week flash discharge test in November, pressure drawdown

test data were collected, and after the one-week test in December and the

two-week test in January-February, pressure buildup test data were collected

by dropping pressure probes to bottomhole. Results from the analyses of

these three tests are given below •

. 1. Pressure Drawdo\'m lAna lys i s

Wellhead pressure vs. time plotted on log-log scales for type-curve

matching and on semi-:-log scales for a pressure drawdown analysis are shown

in Figures 34 and 35 respectively. The initial pressure was obtained from

Figure 36. While these data can be used in a pressure drawdown analysis to

obtain information about the geothermal reservoir, some skepticism must be

di'rect,e'd towards this analysis because of the following reasons:

a.'We analysis is based on a constant production rate during the

. discharge, and this condition was not met during the November test. In

order to apply the theory, a normalized pressure was obtained by dividing

the measured pressure by the concomitant production rate.

-46-

) • • • • • • "

• "

• • • "

• • • • • • • '. .

• • G) • 0.

. ;" => , , -

'~ .' •

o --

-47-

"

""

' ,

o o o -

0 0 -

0 -

. 0

-q 0 0

IU ~ IU

0

~ CI)

CIJ .... CIJ Ol So-

, IU .r:: U CI) ....

0

So-CIJ ..c E CIJ > 0 z:

"- If-.s:;. 0 .. ~

CD 0

E- -0.

i= Ol 0 ..J

I Ol 0

..J

. o;t' C"")

CIJ S0-:=; Ol .....

IJ-

·9'1 iili iii iii iii ,. 'iii

8 '-.

~ I 1_/.· .r::: ...... m = 1.11 psi /klb/h~/cycte

.0 X- I -~ J • ~ 7

CIlI 01..

CIlI '-::J CIlI

~ 6 ,-, a. "'0

LlP1hr /Q = 5.23 psi/klb/hr ...... ~. • 0 I

I (1)1 ?f • ~ :: 5 ()) I <l>

~. • "'0 I (l) •• .!::! 4 - l_ . 0 • E \

'- • 0 Z

I • 3_ • •

21 IIIII IIIII IIIII 11111"1111

o 0.1 10 100 .1000 Time, hr

Figure 35. Semi-log Plot of November Discharge Test Data

800

700 .... .

.600 -." a.. .. e

\ P,= 660 • pSlg

\ 500 :3 . ." fI) Q)

Q:

-c 400 \ ' .

\ c G) .c -Ci) 3:

300

200 -•

100

o o

'T\ \

• ...

5

- ......

. .

r'

' .

• • . . ' .

• • •

•

10 15 20 25 30 Time. min

Figure 36. Linear Plot of Initial Data for November Discharge Test

-49-

35

'-' .

b. There was some overpressure at the well head pri or to th_estart

o.(the .test. .... "., Consequently, opening the valve took some effort and about

2 to 3 minutes were needed to open the valve completely .. Thus, there is

an uncertainty of that amount in the determination of zero time.

c. The theory is fO.r bottomho1e pressure whereas the data in Figures

34 and.35 are for wellhead pressure~ Thus, the assumption must be made

. that wellhead pressure is proportional to downhole pressure and the pro

portionality factor remains constant throughout the test.

Withln these restrictions and assumptions, some information can be obtained.

To normalize the pressure with re~pect to production the pressure relation can

be written as:

where

",'

Pi - Pwf _ '162. 6~B '. k .'. q - kh (10910 t + 10910 .. . 2 - 3.23 + 0.87s) (i)

P. = initia1pres5ure, psi 1

Pwf = flowing pressure, psi

q= production rate, std b~l/day' , .....

II = 'viscosity, cp

CPllCt r w . '.

B= formation volume factor, res vo1/std vol

k = permeability, md

h = formation thickness, feet

t = time, hr , '" = fractional. porosity

Ct = total system effective isothermal compressibility, psi-1

r w = well radius , ft

s = skin effect factor

-50-

The left side of equation (1) is a linear function of 10910t s~ that , P. P'

a plot of 1 i' wf vs. 10g10t will yield a straight line with a slope, m,

psi/bbl/day/cyc1e, where

Iml = 162.6118 kh

and this 'equa-tion can be used to calculate the permeabi1ity-thic"knes's/ktL

Equation (1) can also be used to calculate the skin effect factor, s. . ,

(2)

Letting P1hr be the value of Pwf for t=lhour on the correct semi-log straight

line, equation (l) can be rearranged to yield:

(3)' "

By using (3), the pressure drop due to the skin effect can be calculated from:

Aps q = 0.87 Imls

" . and the flow efficiency:

Pi - Pwf - Aps

FE = ----q~-Pi - Pwf

q

With the assumptions made previously, a log-log type-curve plat of

Pi· Pwf vs. t for the November test is shown in Figure 34. The two uni t-q

(4)

(5)

slope lines shown verify the existence of weI 1 bore storage effects. From the

end of the second straight line, it appears that the semi-log straight line

or the rad.ia1 flow period started at about 10 hours after the test was begun. " p. - p "

Figure 35 is a" semi-log graph of " 1 q wf vs. 10910t. An analysis of"

the plotted data,shows that the permeability thickness:

-51-

kh = (162.6) (24 hr/day) ( 0.09 cp) (1.5 res bbl/std bbl) (350 1b/bbl) (1.11 x 10-3psi/1b/hr/cyc1e)

kh = 1356 md-ft

and if the thickness of the producing layer is assumed to be h = 1000 ft.,

then the permeability:

k = 1.4 md •

The skin effect factor:

~ = 1 15 5.23x10- - log • + ~ 23 = -0 oc 3 1 4 ] -

;,. -3 10 2 .;). .ou

. [1011X10 (0003)(0009)(8x1r-6)(8i~55) The small negative skin effect factor suggests that skin damage is not present.

Therefore, the flow efficiency of the well is approxjmate1y 1, or the well is

discharging as much as it is able to produce.

The minimum drainage area for the duration of the November flow test can

be estimated to be:

A = 0.000264 (1.4)(3.36) = 1.15 x 108 ft2 (O.03)(0.09}(8xl0-6)(O.05)

Thus, the minimum volume reached during this discharge test was:

Ah = 0.8 cu mile.

2. December Pressure Buildup Analysis

As with the pressure drawdown test, the pressure buildup test employs the

standard methods used in petroleum and gas field analysis.- The end of the

December discharge test permitted a pressure buildup test. Bottom-hole pres

sures were taken by two Kuster KPG pressure elements and recorders in tandem

to ensure that pressure data were acquired since considerable difficulty had

been experienced with equipment malfunction because of the very high

temperature.

=52=

'.

Figure 37 is a log-log type-curve plot of (Pws - Pwf) vs. t. It. shows i

two distinct we11bore storage effects as in the pressure drawdowntest; the

top of the second we11bore storage effect is indicated by the Arrow A. The

rule of thumb used is that the onset of the radial flow period on the con

ventional semi-log straight line is 1 1/2 log cycle beyond A, which is indi-

o cated by the arrow B. This time is approximately 70 hours after well shut-in.

( t + L\t Figure 38 is a semi-log graph of Pws -Pwf) vs. 10g10 L\t •

From the curves the permeabi 1 i ty-thi cknesso

:

kh = 162.6 (87.700)(24) ~O. 09)(1~= 880 md-ft t350)(150 0 '

Again, if the height of the producing layer is assumed to be h = 1000 ft~ then

k = 0.88 md-ft. " .. " .'.01>

0' 0

The skin effect factor:

s = 1.15 ,[ 1900 - 467 , 130

10g10 0 .88 0 02 +3.23] (0.03)(0.09)(8X10-6)(8.~~5)

= 4.30

The pressure drop across the skin:

L\ps = (0.87)(1~0)(4.30) = 561 psi

and the flow efficiency:

Fi - 2300 - 467 - 561 -00 65 - 2300-467. - • 0

-.'.:~';-'

This result indicates the well is producing about 65% of the capability with-

out damage. '"

. -53-

'. ,". • •• I ~'

• • • • •

~~~m~.=:~:::~1-------------t-----~----~~----------~·o • Q

. .. •

:\ \~!~::.;.~~.~!, ., . .. . . ' .. , . . ~· .• ·l · ..... . .. . " ,:- ;-. ... .

-

• •

• ,

. ..... .. ". , . • ' 1

" . "

-o o o --

-54-

.. CD E

1=

. "M

f ::s en .,...

u:...

2200

.- . ,-

2000 t------+-------f---~~---_+---_i (!)

00 ~ 0.. .. 1800 0'

~ I ~ 1600 ~------~----~--~--~-----~----------~------~ fa 8: 1400

'$ $

~ o 1200 ~--~--~------------r_------~®----+_--------_+--------_i :I: I .. ~ 1000

~ O $' meoo t------------r~----------r_--__ --~----------------+_--------~

600 ~® ~~@!)~.

$ ~'='

10

Figure 38. Semi-log Plot of December Pressure Buildup Test Data

-55-

I

3. Ja'nuary-Febr'uary Pressure Sui 1 dup Ana lyses

Bottom~ole pressure measurements made after HGP-A was shut-in on Febru

ary 11,1977 produced data and plots similar to that obtained for the December

test. The onset of the conventional semi-log straight line was approximately

70 hours after well shut-in and the slope of the semi-log plot is 105 psi/

cycle (Figur:-e 39) .

. Using these values gives the total effective permeability thickness as:

If the effective height of the producing layer is assumed to be h = ,1000 ft.,

then the effective penneabi1ity k = 1.09 md.

The skin eff\~ct factor: ,.

[1910-774 s = 1.15 . 105 - 10g10

1.089

(0.03}(0.09) 8x10-6

.The pressure drop across the skin:

2 + 3.23] = 6.29 8.755

24 '

~ps = (0.87) (105) (6.29) = 575 psi

Close examinati on of th'e January-February ,discharge data shows that two

consecutive straight~line approximations can be made to the Horner plot (Fig-

ure 39). Interp retation o!this occurrence is that there are'at least two

different production layers in the wellbore with different kh values (Matthews

and Russell)2. The same effect is also present in the December flash data

(Figure 40)', but until it was reproduced in the January-February test, little

credence was given to it.

2 C.S. Matthews and D.G. Russell, Pressure Buildup and Flow Tests in Wells, SPE Monograph Volume 1 (1967).

-56-

2600

2400~------~----~--+--------+--------+-------~ (!)

en 0.. .. 2200 W 0::: ~2000~-------r--------+-----~~----~--+-------~ en W 0::: a.. 1800 m = I05'psi/cycie w ..J

./ ./

./

./ ",

o 1600~--~--~--------~~----~------~+-------~ :c I ./

m =, 260 psi Icycle ~ 1400 ~ ® ~ 0

~1200~-------r--------~~0------+--------+------~ ~

1000

800~~~~~~~~~~~~~~~~~~~~~~

105 10 I

, Figure 39

SEMI-LOG PLOT OF JANUARY PRESSURE BUILDUP TEST DATA

-57-

2200

@ 2000~------+-------4-------~~----~------~

(!) 00 ®

0.. .. 1800 ~

~ I 00 1600~------·+--------+--~--~~-------r------·-1

~ 0:: 0.. 1400

® ®

.".-

~ ® o 1200 ~------~-------+--~~--~----~~-------; :c: I

~ 1000 f-

-® b m 800 ~------~----~-+--~~~~------~------~

600 . -® ®

® ®@!> • .... . ® ~ . 400wt~I~~~~~~~~~~~--~~~~~~~~~

IO~ 104 103 102 10 I t + ttt

At

Figure 40

SEM1':'LOG PLOT OF DECEMBER PRESSURE BUILDUP TEST DATA

-58-

Since the reservoir has at least two producing layers, the trad.)tiona1

Matthews-Bros-Hazebrolck method of extrapolating formation average' pressure

cannot be used and the Miller-Dyes-Hutchinson method (Miller, Dyes and Hutchin

son;3 Perrine;4 Matthews and Russel1 2) must be used to obtain the value of t~e formation average pressure. The value is:

p -= 2174 psi with no influx of fluid over the drainage boundary

or p = 2214 psi with constant pressure at the drainage radius.

Wi.th the above pressures, the flow efficiency values are:

FE = 217~1747~4774575 = 0.59 wit~ no influx of fluid over the dralnage boundary

or FE = 2214 - 774 - 575 = 0.60 with constant pressure at the 2214 - 774 drainage radius •

....

4. Recalculation of December Data

If the analysis of the December Horner plots is redone to account for two

producin~ layers, the permeability thickness:

kh = 162.6 (87,700)' (24) (0.09) (1.5) .. 1553 md-ft • . '. '.' '.' (350) (85) .' '.'

And if the effective thickness of the producing layer is assumed to be

h = 1000 ft., then the effective permeabi1 ity k = 1.55 md.

The skin effect factor: .. .

. [ .

,. s = 1.15 203~5467 -10910 .'. 1.553 . < .: 2 + 3.23 =14.8 ,- --' . . '.' (0.03)(0.09) (Sx1 0-6)(S2~55) . ]

The pressure drop acrossthe"·skin.:

Aps = (0.87) (85) (14.8) = 1098 psi.

2 Ibid. 3 C.S. Miller, A.B. Dyes and C.A. Hutchinson, Jr., The Estimation of Permea-

bility and Reservoir Pressure from Bottomhole Pressl,lre Bui1d~up Characteristics, Trans., HIME (1950).

4 R.L. Perrine~ Analysis of Pressure Buildup Curves, Drill. and Prod.Prac., API (1956). . •

-59-

Employing the Mil 1 er-Dyes-Hutchinson method for calculating th~ average .,' . '. ' .. ' .... :. '~::~.::"~' .... : . '" . ,.' . ::" .(~.~ ' .. ' - ." . ', .. ':': ',' ,', ...•.• ','

formation pr-essure results in formation average pressure values of:

p = 2206 psi with no influx of fluid over the drainage boundary

or p = 2214 psi with constant pressure at the drainage radius.

With these values, one can calculate the flow efficiency to be:

FE = 2206 - 467 - 1098 = 037 2206 - 467 • with no influx of fluid over

the drainage' boundary

or FE = 223~2384~7467l098 = 0.38 with constant pressure at the drainage radius.

5. Discussion

Table 6 summarizes the preceding analyses of the press~re drawdown and

buildup tests. The permeability-thickness figures from all analyses are .. ' similar, but the skin effects and flow efficiencies are different. The

assumptions for a pressure drawdown analysis include the production of fluid

at a constant. rate, which is' difficult to. satisfy inpractice •. J,n order to .,'

apply the theory, the pressure data were normalized by dividing by the pro-. . :' :" ..

duction rate, which can be questioned for its validity. On the other h~nd, '.

the pressure buildup analysis has no similar, difficult assumptionto satisfy

in practice. Thus, more reliable conclusions can be drawn from the pressure ..

buildupte~ts and analyses.

In a preliminary way the analyses of the pressure buildup tests indicate ,';

that the reservoir 'is tight (1 ow permeability of perhaps less than 1 ,"i11i-

darcy) and that the well suffers from si gnifi·cant skin damage, resulting in a . . discharge rate of only 38-60% of what it is capable. This latter tentative.

conclusion is supported by the data in Table 5, which shows that the flow

rates have increased with each test. This may have been a result of the ..

initial surge in each test, which either removed' the baked-in mud and thus

reduced the skin damage, or possibly induced stress-causedmicrofractures.

-60-

.. ' .~ ,..... .... .. .

TABLE 6 .. . . .. . .

COMPAR I SO'NOF PRESSURE DRAWDOWN AND BUILDUP TESTS

CONSTANT DECEMBER DECEMBER JAN-FEB' PRODUCTION . BUILDUP BUILDUP BUILDUP' DRAWDOWN TWO-LAYER ONE-LAYER TWO-LAYER

I PERMEABILITY THiCKNESS" KH" MD-F.T. 1356 1553 880 1089 0\ .... •

ApPARENT SKIN FACTOR" S - 0.86 14.8 4.3 6.3

PRESSURE DROP' ACROSS SKIN" PSI 1098 561. 575

FLOW EFFICIENCY '" 1 ' 0.38 0.65 0.60 .

)

It'a1so appears that there are at least two production laye~s wi~h dif-/

ferent kh values. While the theory does not permit a calculation of the

two kh values, its use indicates that the effective kh probably lies between

1000 and 1500 md-feet.

,"' . ".r:. : ... .-.

Reservoir Recovery Analysis

After each production test, the well was shut in. This quenched the well

flow except for the four-hour te'st on July 22, 1976.

Fi gure: 4'" pr~sents the water 1 evel recovery plots after each production

flow testwhichresu1t~d in quenching of the well flow. The first three flow

test plots. followed a common ,pattern and recovered in about thirty-five days,

although the flow period varied from seven to fifteen' days. The waterrecove'ry

for the 42-day f10wtest, as shown, took almost twice as long to completely

recover. When the plots are redrawn with a common point of zero depth, it is

observed that below 200 feet each plot follows a similar slope (Figure 42).

Table 7 presentsa' summary of the t~me flowed with respect to time recovered. , .

After each flow test was completed and the well shut in,temperatlJreand

pressure profiles were made of the we1lbore.In each case, the temperature

profiles followed similar patterns with respect to time (Fi gures 43 :.. 46).

These are: Depth, feet

0-1500 The temperature decreased sharply and rapidly. At approximately 1300 feet, a temperature in-version existed. .

1500-2500 Sharp temperaturein~rease. 2500-4000 Gradual temperature increase •

. 4000-4300 Hi gh temperature section. 4300-6200 Temperature inversion., 6200-6300 High temperature section.

-62-

". ".:' - .

.. .... ..

.c -0-. I

Q)

0\ "C w I '-

(l) -c 3:

1400, I

&:-® NOV TEST (14 days) [!}--{!J DEC TEST (7 days)

1200 I . I •• JAN/ FEB TEST (15 days) ~ MAR/MAY TEST .(42 days)

1000 I . .. I

800

600

400 I I R > 's(: > < c n

200 I 'm ... ~ '\l\

o ' """-'9 ," ,

I 5 10 50 100

Time t days

Figure 41. Water Level Recovery Rates

I 0\ ~ I

.. --..

.c

1200 ~I ----------------------~----------------------,

1000 11---------------:----

( 800 1 ~ \

G--e NOV TEST (14 days) ID-8 DEC TEST ( 7 days) • • JAN/FEB TEST (15 days) A . J~ MAR/MAY TEST (42 days)

a, ~~ . , ~ 600 I '" ... CD -c 3:

400' 1 '=' ,,~ '.!It . . "" ;;;;;: ~

200 I "'m .. ~ -----of

o ~8

Time

Figure 42. Water Level Recovery Rates (With Common Point of Zero Depth)

TABLE 7

SUMMARY OF WATER LEVEL RECOVERY

Time Flowed (days)

0.17 (41lr)

7-15

42

-65-

Time Recovered (days)

o

35 .- ." .. .,..

65 ..: ":~" i . ",

I m m I

I-w

TEMPERATURE.OC

00 100 200

El A '. '

1000\ \" ~ o ~ $~ . , . , .~ '4~.

2000 I "'~ .. ':'.&. . .... ~ -r' •. ~---.... - =- - .

300 400 --,

~

~

~ .3000 •

:I: I-a. W 0

4000

50001 \ ~~~~1------~~

·6000

JULY FLOW TEST (4 HOURS) -0 7 .. 2 2 .. 76 . after shut down

/A- - - ._/A 7--29-76 7 days after shut down 6 ...... · .. ·8 8-4-76 13 days after shut down

7000' \ -

Figure 43. Temperature Recovery Following July Flow Test

t 0\ 'oJ I

','

TEMPERATURE, °C

00 100 ' 200 300 400 --.

10001 ~

... ~r'-"'e' ............. ;. ~ 2000 I '~,' - ---- __ ~ .. ::'L .. .:.: .. .:.:.::.".:.:~

... l&J ' ~ 30001 ' II Dr

• ::x: to. Ul Q.

4000 I I ~r.-.' ------I .@;l ro

~" /iT I.'

50001 I, ~~------I

6000

. ' ... ' . .

JULY 'FLOW TESTe 4 HOURS ) . ". .

<:> 0 8-12-76 21 days after shut down A- - - -A 8-26-76 35 days after shut down m .. ··· .... m· 9-26-76 66 days after shut down

. 7000'~------------~-----------~------------~------------~

Figure 43. (cont.) Temperature Recovery Following July, Flow Test

'. "

. •

I 0\ ()O I

... LLJ

00

TEMPERATURE.OC 100200

10001 .~ ·~i . I , , r11! , ... "~A '~

" ..... .... " .... :.:-2000 I "l:-'~" . . .~. b

300

~ .. ;,4>

400 -,

~ 3000 ., I"

\ '" \. ,

'. •

::J: .--0.. W Q

4000

..... . ... " .... . .....

" ". ..... A '13" ~, .. -'. " .......... .... '. '-" .....

5000 I I I" . r!tY"~-II--------i

6000

NOVEMBER FLOW" TEST (14 DAYS)

e <:> 11-21-76 4 days offer shut down &- - --It. 11-30-76. 13 days after shut down . 13·;'· .... ·[1 12-4-76 17 days after shut down

7000'---------------------------~----------~------------~

Figure 44. Temperature Recovery Following November Flow Test

~ .. '.

• 0'\ \0 I

TEMPERATURE,·C

0° 100 200 . 300

.~ ~ , ,. , ... , ...

1000 .. \

~.~~., ..•. , .. ;: ........ .. . ..... .... .....

... .... -,. ....... 2000 ....••............. e ..

.... I.IJ ~ 3000' ~ . .. :x: .... 0.. LLI Q.

I t

4000

I;>ECff:MBERFLOW TEST (7 DAYS)

. . \ ..... ,., .... " .

A . ,'1';1 a \!J &;,I •• _ , .... , .... ,

.:"". Jt.-. ...:. \: . . ~

~ Ci

: , ~ rb4

60001--0 0 12-16-76 well flowing, Ip -4 pslg £-- --A 1-3-77 "5 d(lysafter shut down 8·········8 1-15..;77 27 days after shut down

'. \ ,

o

. 7000 I . I" I I

Figure45~ Temperature Recovery Following December Flow Test

400' -'" "

. I ..... o I

00

~A . \ -., \ '. \

TEMPERATURE,OC

100 200

1 10001 fa ~ e . , .. ' ,

aM ' .... ··'m"~ . ,

,. '. ,

I ";'" '1' ~ .', ., 2000 . . '.; "ErA ~

'" " '. , ~'. "., .••.• '&.

I- ~.\

'" W \". W 3000 .... ~ , ..... . :c ' ", .... 'A ·····13 ( • n. ~, ...... . lLJ .... • ••• c ......

. 4000 ...

300 400 --,

5000~--~--~---+--------~---r--~--~~B-~----~----~

JANUARY-FEBRUARY' FLOW TEST (16 DAYS) . .

(£) (£) 2-9-77 well flowing, 13/4" orifice plate in -ttr---...~.~' ,,:,,". ______ ~ fA-- - -fA 2-19-77 8 days after shut down . ....~ ....

. . .. "&l EJ·· .... • .. EJ 2-25-77 14 d.ays after shut down

6000t-

7000 1. . ·1" ·1

.~.

".:.

Figure 46. Temperature Recovery Following January/February Flow Test . . ~ . . . . - ~

' .. ' .

'.

I ...., -I

TEMPERATURE, °C

o 100 . 200 300 400 011 I' i ,

1000 I a$ 0 I'

~ ~ w , '~,

~

2000 I .. <A. --.., T-i:

.... '

w w u. 3000 I ' I . b,,:';A, .. :t: ln.. w Q . ~I~ ____ --i . 4000 1 I· ~~

5000 1 €is I

6000

JANUARY - FIEBRUARY FLOW TEST (16 DAYS)

o 0 3-18 .. 77, 25 days after shut down 1:.-- - -A 3-17-77 34 days ofter shut down

7000~i~' ----------~------____ ~~ __ ~----~--------------

Figure 46. (cont.) Temperature Recovery Following January/February Flow Test

. ~ ..

..

The high temperature sections occurring at similar depths indicate

some activity possibly due to fluid influx. The temperature inversion at

1300 feet could be attributed to the flow of cooler water pa~t the production

casing through the very permeable section located in the near vicinity. The

other and larger inversion section between the two high temperature sections

probably constitutes a lower permeable se,ction.

Immediately following the shut down of the 42-day flow test a number of

temperature and presstfre profi les were continuously made (Figures 47 to 5Q)~,

The following were observed with respect to time at the depths of interest:

Depth, feet

1500, 2280

3270, 3430, 4100, 4260

6080, 6300

Temperature increased as well shut down (due to pressure increase), then steadily decreased (due to condensation and cooling in the casing). -

Temperature increased as well shut down (due to pressure increase), decreased (due to condensation)" then increased (due to influx)

Temperature increased steadily (due to well shut down and influx). ,

Therefore, from the inf9rmation obtained through various examinations,

temperature and pressure recovery profiles,wellbore geology, and continuous

temperature profiles following shut down,it can be hypothesized that the

major production zones are probably located at 4000 to 4300 feet and bottomhole.

In general, as the flow test,period increased, the recovery characteristics

also differed as evidenced by the absence of the change in temperature slope

at 2500 feet after about two weeks shut down follOwing the 42-day production

test. Also the mid-high temperature section shifted as well as expanded from

4000 to 4300 feet to 4300 to 5000 feet. This difference is thought to be

due to the expan~ion of the flash front into the reservoir and hence the

longer recovery period. This was seen in the water level recovery which took

almost twice as long to reach ground level.

-72-

'.

,"

,

300 .. - ....

£0 .. i J ~ ''I £."" ~ !.

' . . '

'.,

_A

0 0 .. CD '-:::J 250 -. c '-Cl) a. E

0IA ~

me. 8eo+ (~ .

~ ~ Gl

'. !J

SP. A ~ 8 • 4 ~ -' UL • ~ J3. C

~ ~ 0 0 0

1!1 0 * * • + .t. lE-

I ...... W I

200

@ 6300' ,

£608Q'. . ~~ !

Gl 4260' r:'I A & , ..

• 4100' ~

~ [!] LIn

£

o 3430' I!l I!l

* 3270' \.

.£ 2280' (!] 1500'

150 0 L r .... ,.

2 4 3 5 6 7 8 9 10 I, Time af·tershut in • hr$'

Figure 47. Temperature Recovery following March-May Flow Test

... --~ ' . . ,

-' 60 £

e

50 ....

E> "

. . ~ .. .".,' . , . ", ' .. . (\1 40 e ~

~. • 0 en

,:,t! * * .. CD A ~ ::J 30 CI) f/) CD ~

0..

. .

£!)to f. ~ ~ . . ..

C) £

20 @ 6300' -.. !J

~ A 6080'

t!] .' s 4260'

• ·4100' , .

10 , 0 3430' .

3270' -

t ..

, £ 2280' [!] 1500'

1 o 5 o 2 3 4 .. 6

Time · after shut in , hrs

. -..- -:.

Figure 48. Pressure Recovery Following March-May Flow Test

-74-

I ...... U1 I

,

00 100 TEMPERATURE,-C

200 300

10001 ~ I I

I VI 2000

400 -

500

tJ) ... 3000 1000 m W ..... ..

ii: 4000 l.IJ C

5000 1 I ).,. I 1:1 ::j1500

6000

2000 7000' . I

Figure 49

MARCH-MAY FLOW TEST (42 DAYS) (i)--(i) 4-19-77 Well Flowing. 3" Orifice plate In

5- 9-77 1st profiht set after shut down IS 5-9-77 5th profile set after shut down 8 5-9-77 6th II n nil.

I 5-9-77 2nd II II. II II II 75-9-777tJ\' II H II II

5

4

II 5-9-71 3rd 5-9-17 4th 'II

Ii . II

.11 II

II I' 8'5-9-11 8th II II II II

.. II 1iJ--..Gl5-22-71 13 days after shut down ~ 8,:,10-7793" .1 II tI

II

II

.l.IJ :s .. :::t: l-e.. LaJ C

PRESSURE t Kg /cm2

00 50 100 150 200 I A- I

MARCH - MAY FLOW TEST (42 DAYS)

@---{!) 4 -19 -77 Well Flowing, 3" Odfice plate in

10001 ~ 5 - 9 -77 I st profile set after shut down

2 5- 9 -77 2nd II II II .. II

3 5-9 -77 3rd II II II II .1

m----m 5 -22" 77 13 days after shut down ~ 500 I '-

2000 I

132

I "m .. I C/) cr;

.... 3000 w W I as 1000 ~ LLJ I LL I 3 ... ::E ......,

0\ •• I .. ::c ::c .... 1-- 4000 3 0.. a.. 3 W W 0 0

\ 1500 5000.

6000 I · 2 .... 3 t f 3 I '1: 2000

7000LI __________ L-________ ~ __________ ~ ________ ~

Figure 50. Pressul'e Recovery Following March-May Flow Test

.,.'

Noise Level Reduction

An apparent noise problem was encountered during the first long-term flow

test (four hours) on July 19, 1976. The sound readings approached levels

equivalent to an ascending 747 jumbo jet (~122 dB at the roadside). Figure

51 and Table 9 present the recorded noise level during this period.

In anticipation of the longer flow tests, a silencer/separator unit was

installed at the ·site. The noise level was reduced substantially -- 87 dBa

was recorded at the roadside. The average sound level about the fenced area

(50 1 x 80 1 ) was approximately 101 dBa. Since the permissible exposures ex

pressed in Table 8 are:

TABLE 8 .-

Overall Sound Pressure Level (dB) Time of Ex~osure {min)

90 300

100 . 50

110 16

120 8

125 5

(Reference: Symposium on Noise in Industry, University of Adelaide, 1968, Vol. 2)

all workers and visitors were required to wear ear muffs within the security

fencing.

During the November and December flow tests, however, numerous complaints

were received from the nearby residents about this roaring noise. Therefore,

some modifications were made to remedy the problem. These included circular

stiffeners welded at two heights on each vertical stack and a specially-

built horizontal discharge line. The muffler, of standard design, is six

feet long and made up of two annular sections, the inner one filled with

-77-

- papaya grove

... :

.... - 50 ·-~~+..Io(i--- 50' ... /- 50 I_.~~-

97' +@

100'

I d•

Well CD ®

-reservoir located approximately 10. feet above wellhead

' __ ": 4' __ •

Figure 51. Noise Levels During July 22, 1976 Flow Test

-78-

"

July 19-, Vertical position

1 2 3 4

1 2 3 a' A or

1 2 3 4 1 2 3 4 b l

c l

Cl i

1 2 3 4

TABLE 9 NOISE MEASUREMENTS

1976 Discharge (discharged at 12:42 pm)

sound level (dBC) 94

100 105 113 125 125 122 122 124 124 122 120 122 125 117 117 119 112 107 91 119 114 113 116

time 12:42 12:42 12:43 12:44 12:44 12:45 12:45 12:46 12:47 12:49 12:49 12:50 12: 51 ~2:52 12: 52 12:43 12:54

. '.~ . r-·

, 12:58 (113,,1:03) 12:59

1 :02 1 :05 1:06 1 :06 1 :04

Horizontal Discharge (93 dBC, 2" discharge @ CD) position dBC'

1 113 2 111 3 112 4 116 b' 108

Vertical Discharge 1 2 3 4

117 112 112 113

-79-

time 1:25

,1:25 1 :26

,1 :27 1 :28

1:56 1 :56 1:57 1:52

ci'nders for absor'ption of the noise, while the outer section is empty

(Figure 52 J.

These changes resulted in decreasing the low frequencies associated

with uncorrifortable sensations of the chest and abdominal area (15 - 45 Hz).

It appeared that while some of the noise sources have been reduced (80 dBa at

the roadside), the important source, that of the circular stacks air colu'mn

was not and that this "organ pipe" remained as the primary source of sound.

Another problem which may have reduced the muffler's efficiency was the

silica buildup on the cinder which bonded the parti~les together into 'one

solid piece.

It was discovered that restricting the fluid flow via orifice plates also'

reduced the noise level. The full flow sound readings were decreased by an

average of six decibels with the addition of the 1 3/4" orifice plate. Figure

53 and Table 10 show the sound measurements recorded for each production

flow test.

SCALE DEPOSITION

There is a substantial problem associated with the deposition of scale, ..

primarily from dissolved silica. As an example,the muffler that was installed

to reduce noise (refer to Figure 52) uses an annular region filled with

cinders as a sound absorbing agent. However, after only 16 days of flow, the

scale deposited was sufficient to cement the cinders together so that removal

required extensive chipping of the bound cinders.

-80-

Figure 52

, HAWA I I GEOTHERMAL PRO,.JECT FLOW TEST EQUIPMENT AND INSTRUMENTATION

WITH MUFFLER

WIRE LINE DOWNHOLE . GAGES AND SAMPLER

MASTER VALVE

• co --'

•

TO TWIN CYCLONE SAMPLER' .

GLOBE VALVE

WELLHEAD PRESSURE TI AND . TEMPERATURE

LIP PRESSURE .

SEPARATOR . AND SILENCER STACKS

WATER TEMPERATU: WATER HEIGHT

(LIQUID FLOW RATE

(TOTAL MASS FLOW RATE) \ .

]( CALORIMETER

(STEAM FRACTION) .,

~ ~ ~

77/3/76 · 1 NOV. TEST ) 1116176

See Tab7e 10 .4-17/17/76

V \

DEC. TEST 12/14/76

.>-. fl27177 ~

JAN./FEB. TEST

2/10/77 "....-

HAI/CHIHAr TEST l3130177

" 5/7/77

----,

."

0 :c 0

',~ 9 8

~ i , . , . f

I

.....

'" ..... · ~7 78 20

022 0 0

12 ;t1 I 0

:t:o

I

i 0

21 2,).

,ll~ 17'ft

I 13 ~ ~1 14~~

6

.~ Not to Scale ~23 24

. ~ 100 ft

3~--~~4~----____ ~~~~~ __ -J

5

~ o 10 20 ft . Figure 53. Map ShOWing Sites fo,. NOise LeVel Readings

11 /3 fl ashcd 11/3 recorded

Station 11/6 recorded

1 10~/9a

·2 104

3 98/106

4 98

5 98/911

6 96

7 98/97

8 99

9 98

10 98

11 101

12 107

13 110

14 107

15 106

16 104

17 110

18 106

19 103

20 103

21 104/101

22 100

23 100/99

24 99

2S 106/101

26 103

27 110

28 110/107 ,

29 96

30 108

31 106

32 97

33 87/-

TABLE 10

Noise Level Readings on DBA Scale (See Figure 53 for locations of stations)

- -. 2/10/77

11 /3 fl ashed 12/12 flashed 1/26 flashed 1 3/4" 11/17 reco"ded 12/14 recorded 1/27 recorded Orifi<:L

9:3 .99 96 92

102 104 100 92

95 96 . 93 85

96 100 96 87

94 94 89 50

92 . 95 90 81

96 97 91 82

97 98 93 85

97 99 94 88

96 99 96 89

98 100 96 90 .'

103 106 100 93

108 110 103 ~,;

102 104 100 93

102 106 102 96

101 105 101 93

105 108 101 96

102 106 99 93

102 104 99 95

99 100 96 90

99 101 98 92

98 99 96 81

97 98 94 81

97 98 95 88

99 101 95 .90

99 101 98 . 93

104 109 103 97

103 107 102 96

94 96 91 86

104 106 101 96

104 108 100. 94

9S - -- - .. 80 74

-83-

3/30/77 I 517/77 : 3" Orifice~" Orific~

98 -100 98 ! 95 91

96 94 1 91 - i 91 89 ! 91 89 I 93 91

95 93 i 96 94

- -101 99 j

I

103 101 l

100 98 I 103 100 ! 102 99 ! 102 99 ! 100 98 i

: ' .. 99 97

; i .

96 95 1 ;

97 95 1

96 94 : ,

94 92 i

95 93 , 96 95

98 96 . 102 100 I 102 100

93 90

103 102 I

102 99

- -80 75

-

SUMMARY

HGP-A has undergone five flash discharge tests since an initial flashing

on July 2~ 1976. The maximum bottomho1e temperature during quiescent periods

has been measured by 358°C.

Comparison of flow characteristics during the early stages of the last

flow tests shows that with each subsequerit test the flow rate has increased.

A possible explanation for this improvement in well performance is that skin

damage due to the use of drilling mud is being alleviated, as each flow test

partially cleans cut embedded mud.

A series of throttled flow tests indicates that there is a substantial

in~rease in wellhead pressure from 51 psig to 375 ps!g as the mass flow rate

is reduced from 101 Klb/hr to 76 Klb/hr. ,The electrical power.outpu'tp'os's,ib'le"

from these flow conditions varies from 3.1 to 3.5 MWe.

Temperature and pressure profiles taken during flow tests indicate that

the fluid in the wellbore is at saturation conditions with a mixture of

liquid and vapor flowing up to the wellhead, that is, with flashing occurring

in the reservoir. The pressure profiles consist of three approximately cO.n

stant gradient lines that intersect at the junction of the casing and slotted

liner and at approximately 4300 feet, from which inference can be made that

the major production zones are near bottomhole and in the vicinity of 4300

feet.

Pressure drawdown and buildup analyses yield a kh value (product of ,

permeability and prodUction zone thickness) of approximately 1000 mi11idarcy

feet with the pressure drop across the apparent mud-damaged skin to be

approximately 500-600 psi. Data points on the log-log Horner type plot seem

-84-

to fallon two different but consecutive straight-line approximations.. In

terpretation of this occurrence is that there are at least two different

production layers in the wellbore with different kh values.

Table 11 is a summary of results of tests thus far .

. / .

-85-

TABLE 11

SUMMARY OF PRELIMINARY TeST RESULTS AND ANALYSES

KAPOHO GEOTHERMAL RESERVOIR

1. LIQUID-DOMINATED

2. TIGHT FORMATION: PERMEABILITY THICKNESS--I000 MD-FT

3. VERY HIGH TEMPERATURES--350°C

4. SLIGHTLY BRACKISH WATER

5. POTENTIALLY LARGE RESERVOIR

6. HIGH SILICA CONTENT I

~ HGP-A GEOTHERMAL WELL

1. ,2.

3.

4. 5. 6. 7.

DURING F~ASH BOREHOLE CONTAINS STEAM AND WATER AT SATURATION

FLASHING OCCURS INFoRMATION

HIGH WELLHEAD PRESSURES--160 PSI AT 95 KLB/HR STEAM OR . 375 PSI AT 39 KLB/HR STEAM

PRODUCING REGIONS PROBABLY NEAR BOTTOM HOLE AND 4300 FEET

PROBABLY HAS SEVERE SKIN DAMAGE

POTENTIAL POWER OUTPUT--3.5 MWE

FLOWS HAVE INCREASED WITH EACH TEST

April 28,

April 29

May 1

May 2

May 4

May 6

May 11

May 19

May 20

June 4-5

June 6

June 6-7

June 6

June 8

June 11

June 15

June 22-24

. June 26

June 30

July 1-2

July 3-6

July 6

1976

Chronology of Events at HGP-A

Drilling completed to 6456 feet.

Temperature profile measured.



Temp~rature proftle measured.




Te~perature profile measured.

Mud flushed out of well.


Pump down test.


Temperature/pressure profile measured.

. Temperature profile measured.



First air lifting attempt -- unsuccessful because ~250' of air hose was lost down the well.

Temperature profile measured •


Second air lifting attempt -- successful -- well flashed for ~5 minutes.

Wel1bore heated daily.


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July 7,· 1976

July 8-12

July 12

July 13

July 14

July 15-18

July 19

July 20-21

July 22

July 29

August 4

August 12

August 11

August 18

August 19

August 26

Sept. 2

Sept. 11

Sept •.. 26

Oct. 6

Oct. 12

Oct. 13

We11bore heated and temperature profile measured.

We11bore heated daily.

Temperature/pressure profile measured with the discharge temperature kept constant at ~80°C.

We11bore heated.

We11bore heated and temperature/pressure profile measured with the discharge temperature kept constant at ~86°C.


Wellhead instrumentation set up. Well flashed vertically as well as horizontally for about 1 hour.


Well flashed for 4 hours. Temperature/pressure profile measured after well was shut in.




Downhole water samples obtained.

Temperature profile measured -.:. downhole water samples obtained •.



. Temperature/pressureprofil e measured •.



Casi.ng integrity test conducted to determine whether casing has collapsed at any point; results negative. .

Downhole water samples obtained. Temperature profile measured on.1ower half of well.

Temperature ptoffl e measured on upper half of well . Water influx test conducted to determine .whether production regions might be at 2090·,4320·, and 5747 1 ; clock failure led to inconclusive results.

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.,

Oct. 21-28,

Oct. 29-30

Oct. 31

Nov. 1-2

Nov. 3

Nov. 8

Nov. 13

Nov. 17

Nov. 18

Nov. 19

Nov. 20

Nov. 21

Nov. 22-28

Nov. 30

Dec. 1

Dec. 2

Dec. 3

Dec. 4

Dec. 5-7

Dec. 8

Dec. 9

Dec. 10

Oec. 11

Dec. 12

1976 Silencer/separator, discharge line installed. Instrument shack erected. Dry well excavated. Kicker installed.


Temperature/pressure profiles measured. Second water influx test conducted at the same depths, but clocks failed again.

Wellbore heated slowly.

Start of two week flow test.

Security fence completed. Lighting and electrical lines installed.

Ten foot dummy probe sent dcwnhole while well was flowing to determine whether temperature/pressure profiles can be measured during flow. Probe caught in wellhead.

Well shut in at end of two week flow test.

Dummy probe removed.

Temperature/pressure profiles measured. Water depth measured.

Water depth measured.

Temperature/pressure profiles measured. Water depth measured.

Water depth measured daily.


~ater depth measured.

Downhole water samples obtained. Water depth measured.


Temperature profile measured. Water depth measured.


Temperature profile measured. Water depth measured.


Well flow induced by air lifting.

Wellbore heated.

Start of one week flow test.

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Dec. 14, 1976

Dec. 15

Dec. 16-17

Dec. 19-20

Dec. 21-26

Dec. 27-29

Dec. 30

Jan. 1, 1977

Jan. 3

Jan. 4-6

Jan. 7

Jan. 8· ...

Jan. 10-14

Jan. 15

Jan. 17

Jan. "19

Jan. 21

Jan. 24

Jan .. 25

Jan. 26

Jan. 28

Temperature/pressure probes lost while making d0w.n~ole measurements.

Flow throttled to a lip pressure of "'4 psig.

Temperature/pressure profiles measured with the lip pressure set at 'V4 psig.

Well shut in and pressure buildup test started. The clock failed so the well had to be opened and flow resumed. After well flow stabilized, the well was shut in once more. Pressure probes were continually sent downhole for pressure bottomhole measurements.

Bottomhole pressure and water depths measured daily.


. Bottomhole pressure and water depth measured.

Bo~tomhole pressure and water depth measured.

Temperature/pressure profile measured. Water depth measured.


. . Si 1 encer removed for modi fi cati ons.

·":'Bottomhole pressure and water depth measured.

Water depth measured daily. Geophysics people running tests at well site. .

Temperature/pressure profiles measured •. Water depth measured. . ,


Water depthmeasured~ Separator stacks removed for modifications. Muffler installed~

Muffler filled with sound absorbent material: cinder.


Water flows out of discharge line. Downhole water samples obtained. All modifications· at well site completed: muffler, stacks, platform, spool and stilling basin.

Downhole and surface water samples obtained. Well surged three times to clean the well. Start of 15 day flow test.

Temperature/pressure profile measured with well flowing.

-90-

Jan. 29, 1977

Jan. 30

Feb. 1

Feb. 2

Feb. 3

Feb. 4

Feb. 6

Feb. 8

Feb. 9

Feb. 11-12

Feb. 13 .

Feb. 14-15

Feb. 16-18

Feb. 19

Feb. 21, 23-24

Feb. 25

Feb. 27

Feb. 28

March 5

March 7

March 8

March 9-15

6" orifice plate installed.


Temperature/pressure profile measured with 4" orifice plate in place.

3" orifice plate installed •

. 2 3/8" orifice plate installed.

Temperature/pressure profile measured with 2 3/8" orifice plate in place.


.1 1/2" orifice plate installed. A pinhole leak in the discharge line was detected. A welder came out· to fix it. 1 3/4" orifice plate installed. .

Temperature/pressure profile measured with 13/411 orifice plate in place. ~

Well shut in and pressure buildup test started. Pressure probes were sent down continually for bottomhole pressure measurements. . .

Bottomhole pressure and water depth measured.

Bottomhole pressure and water depth measured. Downhole water samples obtained.

Bottomhole pressure and water depth measured daily. Muffler interior examined -- cinder bonded together by silica.

Temperature/pres·sure· profile "'~easlired. Water depth measured.


Temperature/pressure profile measured. Water depth measured.




Water depth "measured.

Temperature/pressure profile measured. Water depth measured. The bonded cinder in the muffler was partially removed with an air-hammer.

Bonded cinder in the muffler was partially removed. Water depth measured periodically.

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March 16, 1977

March 17

March 18-20

March 21-27

March 28

March 29

April 5

April 6

April 12

April 19

April 27

May 9-10

May 11-1~

May 17

May 18

May 19

May 22

May 28

June 1

June 4

June 8


Temperature/pressure profile measured. Water level at ground leve1.


Well surged daily for approximately one hour.

Start of 42-day flow test.


Temperature/pressure profile measured. Downhole water samples attempted -- no fluid present in container.

Downhole water samples attempted -- little fluid present.


Temperature/pressure profile m~asured.

Pressure profile measured.

Well shut in and temperature/pressure profile measured constantly for three hours, temperature profile measured constantly for next six hours, bottomho1e pressure measured, then downhole water samples were obtained: two at 6300' and one at 4300' before. Water sampler and 1000' of wire lost downhole.

. Well site cleaned; wellhead, discharge line, muffler 'and ;>;,,·;t)1s;ttument shed repainted. Old wire 1 ine removed from

'spool.

~able from Geophysics fitted on HGP's spool -- too large.

Fishing attempt with a borrowed winch set up. Wire bundles . were retrieved on three separate occasioris -- nothing on two others.

Fishing attempted -- no wire or water sampler was'retrieved on three occasions.

\ Temperature/pressure profile measured. Water depth measured.





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June 11, 1977

June 15

June 18

June 22

,





. '~""

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,. , .

TECHNICAL PAPERS

Chen, B., et al., "Well Test Results from HGP-A," Geothermal Resources 'Council 1978 Annual Meeting, pp. 99-102, Hila, Hawaii (1978).

Chou, J., et al., "Regenerative Vapor Cycle with Isobutane as, Working Fluid,1I Geothermics, Vol. 3, No.3, pp. 93~99, 1974.

Kihara, D. and P. Fukunaga, "Working Fluid Selection and Preliminary Heat Exchanger Design for a Rankine Cycle Geotherma.l Power Plant,1I Proceedings of Second U.N. Symposium on Development and Use of Geothermal Resources, Vol. 3, pp. 2013-2020; 1975.

Kihara, D., et al., IIInstrumentation and Test Results for Hawaii Geothermal Project'sHGP-A Well," Summaries of Second Wqrkshop on Geothermal Reservoir Engineering, pp. 109~115, Stanford, California (1976). :

Kihara, D., et al., "The Hawaii Geothermal Project," ANS Topical Meeting on Energy and Mi nerd 1 Recovery Resea rc~, Golden, Color-ado .( 1977) . '

Kihara, D., et al., "Summary of Results of HGP-A Well Testing, "Summaries of Third Annual Workshop on Geothermal Reservoir Engineering, pp. 138-144, Stinford, California (1977).

Seki, A., et al., "Geothermal Reservoir Performance Prediction," ASCE Journal of the Power Division, Vol. 104, No. P02, pp. 169-181, 1978.

Takahashi, P. and B. Chen, "Geothermal ,Reservoi r Engineeri ng," Geotherma 1 Energ,l, Vol. 3, No. 10, pp .. 7-23, 1975. .

Takahashi, P., et a 1., IIState-of-the-Art of Geothennal'Reservoi r Engi neering," ASCE Journal of the Power Division, pp.1l1-126, 1975.

Yuen, P., etal., IIPreliminary Well Test Results from HGP-A," Geothermal Resources Council 1977 Annual Meeting, pp. 309-310, San Diego,California (1977).

TECHNICAL REPORTS

TR No.1, "Modelling of Hawaiian Geothermal Resources," P. Cheng and P. Takahashi, Nov. 1973.

TR No.2, "Steady State Free Convection in an Unconfined Geothermal Reservoir," P. Cheng and K. H. Lau, March 1974.

TR No.3, "Geothermal Reservoir Engineering: State-of-the-Art," P. Takahashi, et al., May 1974. .

TR No.4, "Regenerative Vapor Cycle with Isobutane as Working Fluid,"J. Chou, et al., June 1974.

TR No.5, "A Parametric Study of a Vertical Heat Exchanger Designed for Geothermal Power Plant Application," G. Shimozono, et aL',Sept. 1974.

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TECHNICAL" REPORTS (.co~tinued)

TR No.6, "Characteristics of Vapor Flashing Geothermal Plants," R.Ahluwalia and J. Chou, Nov. 1974 •

. ' TR No·. 7, "The Effect of Dike Intrusion on. Free Convection in Geothermal Reser-voirs,lI K. H. Lau and P. Cheng, De.c. 1974. .

TR No.8,. "Numerical Solutions for Steady Free Convection in Island Geothermal R~servoirs,1I P. Cheng, et al:, Aug. 1975.

TR No.9, liThe Effect of Steady Withdrawal of Fluid in Geothermal Reservoirs,lI P. Cheng and K. H •. Lau, May 1975.

TR No. 10, IIFree Convection about a Vertical.' Flat Plate Embedded in a Saturated Medium with Application to Heat Transfer about a Dike," P. Chehg and·W. J. Minkowycz, Oct. 1975.

TR No. 11, "Free ConveGtion about a Vertical Cylinder Embedded in a ·Porous Medium,1I W •. J. Minkowycz and P. Cheng, Nov. 1975. .

TR No. 12, IIBuoyancy Induced Flows in'a Saturated Porous Medium Adjacent to Impermeable Horizontal Surfaces,lI P. Cheng and I. Chang, Nov. 1975.

TR No. 13, "The Influence of Lateral Mass Efflux on Free Convection Boundary layers in a Saturated Porous Medium," P. Cheng, April 1976.

TR No. 14, "Similarity Solut,ions for Convection of Groundwater Adjacent to Horizontal Imperr.leable Surfaces with Axisymmetric Temperature Distribution, It P. Cheng and W. C. Chau, April 1976. '

TR No. 15, "Combined Free and Forced Boundary Layer Flows about Inclined. Surfaces in a Porous Medium," P~ Cheng, June 1976 .• '

TR NO.16~ IISi;ini'~aritY~'~lutions for'Mixed Convettion from Horizontal ':I~perme~ble . , Surfacesi n a Saturated Porous Medi a, 1\ P • Cheng, Aug. 1976." ,

TR'No. 17, IINumerical Solutions for Transient Heating and Withdrawal of Fluid in a Liquid-Dominated Geo:therma1 Reservoir,1I P. Cheng andLTeckchandani, Aug. 1976. .

TR No. 18, "Conceptual Design of a 10MW Regenerative Isobutane Geothermal Power Plant." A. Gupta and J. Chou, Oct. 1976., "

TR No. 19, "The Geothermal,Reservoir Engineering of HGP-A: A Summary Report of Activities Up to October 31, 1976,11. B. Chen, et al., Oct. 1976.

TR No. 20, "Workin,gF1uid Selection and Prelimimiry Heat Exchanger Design for a Rankine Cycle Geothermal PowerPlant,1I D. Kihara andP.Fukunaga, May 1975.

TR No. 21, "Possible Similarity Solutions for Free Convection :Boundary Layers Adjacent to Flat Plates in Porous Media," C. Johnson and P. Cheng, Dec. 1976.

TR No. 22, "Computer Performance Matching and Prediction' of Geothermal Reser-, voirs," A. Seki, etal., March 1977.

. ~, .

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rrCHNICAL MEMORANDA

··fM No.1, "Warm Water Wells on the Island of Hawaii ," S. Shito, Jan. 1974.

TM No.2, "Geothema1 Reservoir and Well Test Analysis: A Literature Survey," B. Chen, Sept. 1974.

'TM No.3, "A Review of Problems on Scaling and Corrosion in Geothenila1 Plants," A. Bhargava, et al., June 1975.

i:UARTERL Y REPORTS

·Ouarter1y Report No. 1 , " J. Augustus, et al., Sept. 1 , 1973.

'quarterly Report No. 2, " J. Augustus, et al., Dec. 1 , 1973.

<Q!uarter1y Report No. 3, " J. Augustus, et al., March 1 , 1974.

"Quarterly Report No. 4, " H. C. Chai, et a 1. , Sept. 16, 1974.

"~lJa rter 1 y Report No. 5, " H. C. Chai, et al., Jan. 15, 1975. .-

~ROGRESS REPORTS

::i~ai, H. C., et a1., "Engineering Program Progress Report," Jan. 1, 1975 to Aug. 31, 1975.

Chai, H. C., et ale ,. "Phase 1 Report," Jan. 1975.

"ogress Report on the Dri 11 i ng Program, II May 5, 1976.

':~ogress Reports for FederalFY 77", Jan. 1, 19i7; April 1, 1977; July 1, 1977.

i.:LL TESTING REPORTS (monthly)

';?rogress Report," Sept. 1, 1976 - Oct .. 31,1976.

ll<progress Report," Nov. 30, 1976.

aPr-ogress Report," Jan. 1977.

"Progress Report," Feb. 1977.

"Progress Report,1I April 1977.

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HAWAII . GEOTHERMAL PROJECT...HAWAII . GEOTHERMAL PROJECT HGP-A RESERVOIR ENGINEERING " September...

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