SPE/lADC 29381

Hole Cleaning Program for Extended Reach WellsG.J. Guild, T.H, Hill Assocs.; I.M. Wallace, Phillips Petroleum Co. U.K.; and M.J. Wassenborg,Amoco U.K.

SPE Members

Copyright 1SS5, SP131ADC Drilling Conference.

This Pa@r wee prepared for presentation at the 1s95 SPE/lADC Drilling Conference held in Amaferdem, 28 Februery-2 March 1SS5.

This paper waa selected for presentation by an SPE/iADC Program Committee foliowing review of information conteinad in an abatract aubmiftad by the euthOr(e). Contents of the paper,se praaanted, heva msf bean reviewed by the lntemWtonal Aeaociaticn of Orifling Contracfore or the Sm3ety of petroleum Engineers end are eubjact to correction by the author(s). Thematerial, aa preaamed, dose nor naoasaarily raffact any position of the SPEw IAOGtha~offiwa or ma-. pm -m~ at sp~lAoc m*t@s we a’ubi~ ~ p~ika~onrewiaw by Edlfcdal Committees of the SPE and IACC. Permiaaion to copy is reetrkted to an abafracf of not more than S00 words. Illuafratbna may not be copied. The ebatmct shouldcontain conspicuous a&moWadgmant of where and by whom the paper is praaanted. Write Librarian, SPE, P.0, Sox SS2S2S, Richardson, TX 75DSWS26, U.S.A. Telex, 1S2245 SPEUT.

Abstract

This paper presents a hole cleaning program developed in the

field by Amoco UK over the course of three extended reach wells.

This program has be effective in cleaning the hole as well as

increasing drilling progress.

Introduction

Over the last decade many hole cleaning recommendations have

been based on laboratory experiments under controlled

conditions. These experiments normally involved a flow loop

with an inner pipe which was meant to stimulate a drill string in

a wellbore. The inner pipe may not have been rotated during these

experiments. If it was rotated the revolutions were often iow

(<100 rpm). Also, the pipe was nearly always laterally restrained.

Under these conditions, several of these experiments have indicated

that pipe movement is not a primary factor in hole cleaning. ‘“ 2)

Despite this, field personnel engaged in extended reach drilling

operations have not only shown pipe movement, i.e. high rpm, to

be important in the hoie cieaning ‘3’4) but have used pipe

movement as a basis for developing effective hole cleaning

programs. This paper describes one such program developed by

Amoco UK over the course of three extended reach wells. The

objectives of this hole cleaning program have been to improve

extended reach drilling performance by:

1. Avoiding stuck pipe.

2. Avoiding tight hole on connections and trips.

3. Maximizing the footage drilled between wiper trips.

4. Eliminating hole cleaning backreaming trips prior to

reaching casing point.

5. Maximizing daily drilling progress.

A discussion of how this hole cleaning program has been

implemented and its positive impact on extended reach drilling

performance is presented below.

Aiiioeo UK Extended Reach W6’!!S

r. A.. . . .. . fif A va~fin; u tly= hnle clennin~ nrt-smam AmWO IJKXII UK ~ubati U1 Uevw “Y.ne.. - ..-+ -.-- .....O=._=._...:.

has drilled three extended reach wells: Arbroath Field wells T14

and T19 in UK Block 22/17, and North Everest Field well SEER

T12 in UK Block 22./lOa. All these wells drilled the same type

formatkm @httied iirn.e~t~ne)using generally the same hole and

casing sizes, mud weights and drill string configuration. In

addition, as shown by figure 1, all wells had approximately the

same type of well path (build & hold with constant azimuth) and

425

.

2 Hole Cleaning Program for Extended Reach Wells SPWIADC 29381

1000

AR BROATH T143000

TVD(teet)

500013 31V CSG @ 7068’MD

7000 .--- ... . . .TD = 15U.5< MU

9000 1 I 1 1 1 1 1 (o 4000 8000 12000 16000

Vertical Section (teet)1000

AR BROATH T193000

TVD(feet)

500013 318” CSG@ 8246’MD

700095M”CSG@ 17256 MD

90007“Lrner@ 19000 MD

1 1 1 1 I 1 1

0 4000 8000 12000 16000

Vertlcel SectIon (teet)

100

1000

L

NORTH EVEREST SEER T123000

TVD 2 degreesl(teet)

5000

t

31VX 135\6” CSG @ 12006’MD

95/6’ cSG@ 22042’MD5 1L2-Liner

90001 I I , 1 1 I 1 , 1 ,

0 4000 8000 12000 18000 18000 24000

Verticel Section (teet)

“.4 .X,... . . . . . . . rn. Am. n. ., ..- . “m-m m. .

approximately the same tangent angles (71-76 degrees). T14 was maintain rig crew awareness to a high degree with respect to down-

displaced approximately 12,500 ft from the platform, T19 was

displaced 15,000 ft and SEERT12 was displaced approximately

21,000 ft. T14 did not reach its objective; it was lost, in part, due

‘4) It was because of this loss that an effortto poor hole cleaning .

was made to develop a more rigorous hole cleaning program which,

in turn, would help improve drilling performance. Even though

much of this improvement can be attributed to better bit, BHA and

drilling fluid performance, the cleaning program played a

contributing role.

Implementation

The philosophy of Amoco UKS hole cleaning program is to

hole conditions. To do this, a three prong approach is taken:

1) Wellsite monitoring of torque and drag parameters.

2) Monitoring the rate of cuttings returned over the shaker.

3) Monitoring the volume of the active mud system.

Wellsite Monitoring of Torque and Drag

Wellsite monitoring of torque and drag is not new(s). Its use as a

means of determining hole cleaning in extended reach wells has

been adopted and routinely used by Amoco.

Basically, the procedure involves the driller recording, prior to

426

.

SPWIAX 29381 Guild, G.J., Wassenborg, M. J., Wallace, I. M. 3

String Weight (Klbs)200

190

180

170

160

150

4,4n, y“

130

120

110

I

:::.;l? Clean

\High ROP,LJe;3C2fy. .

D.- A;..A..A &u;op90~oblems

.Rotating Wt.

,Aclual

100t Slack Off Wt.

90 I . . . . . . . . . . . . . . . . . . . . . . . ..l . . ..l . . ..a.. ..t . . .. fi. . ..l . . ..t . . ..#....#.2061 2542 3022 3503 3982 4462 4942 5423 5906 6477 6663 7343 7727 6205

Measured Depth (feet)

each connection, the pick up, slack off and rotating off bottom drill

string weight (with the pumps off). These actual vahes are plotted

along with predicted pick up, slack off and rotating off bottom

weight. Tiie predicted vaiues are cdcuiated using a ccxnrnercidly

available PC program which is based on a tension-torque model

developed by Johancsik, et al (61. In addition, while rotating off

bottom the torque is also recorded. This exercise yields several

results:

1) The very act of recording the pick up, slack off and rotating

off bottom weights each connection increases the driller’s awareness

of down-hole conditions.

2) When plotting the actual against predicted weights, it has

been found that when the hole is clean the predicted and actual

values agree within 5,000 to 10,000 lbs. An example of this is

shown by Figure 2, this figure displays the pick up, slack off and

rotating off bottom weights of the 16 inch hole section in Arbroath

T1 Q-.-.

, CircHoleClean

A

@ 5607High Rop,Wet Pick upwt.Corm.@5326’ __,

I ‘?

DiwgingTrend=Deteriorating IHolacoIldi&

Co&WTrand

I . ImprovingHoleconditions

I

%SlackOffWt.

A 1 I A

5423 5906

Measured Depth (feet)

Fig. 3- Diverging/ converging drsg trends, Arbroatb T19.

(–Dtaii of Fig. 2j

427

4 Hole Cleaning Program for Extended Reach Wells SPE/IADC 29381

Torque, (ft-lbs)

❑ Off Bottom Torque Before Circulating Hole Clean

❑ Off Bottom Torque After Circulating Hole Clean

30000

25000

m I20000

15000

12458’ 15078’ 16093’ 16559’ 17585’

Measu red Depth (feet)

Fig. 4- The off bottom torque before aad after circulating the hole clean, 12 1/4 inch hole section, SEER T12

3) A divergence of actual pick up and slack off weights over 4) Off bottom torque can be used to help determine if the hole

several connections indicates that the hole is loading with cuttings. is clean. In the case SEER T] 2, it was found that when the hole

Conversely, a convergence indicates the hole is cleaning up. An was clean, the off bottom rotating torque was higher than when the

example of this is shown by figure 3. Figure 3 is an expanded detail hole was loaded with cuttings. As shown in figure 4, this was

of figure 2 focusing on the connection at 5326 ft MD. This figure evident when comparing the off bottom rotating torque values

shows that as the well is being drilled and the hole is loading up before and after circulating the hole clean at the same measured

with cuttings, the weight increases when picking up and decreases depth. Because the shale cuttings were firm and hard, it is

when slacking off (diverging trend). If operations were to continue thought that the cuttings within the cutting bed acted as ball

without addressing the problem, divergence would continue until bearings with respect to the drill string in rotational mode. This

ultimately the drill string would be stuck. The hole is circulated result would not be true for all extended reach wells; it would

clean at 5807 ft MD and the next several connections show the pick depend on the thickness of the cutting bed, the formation type and

up and slack off weights converging. drilling fluid characteristics.

Tracking divergence/convergence trends is a good method of The Role of the Wellsite Drilling Engineeroptimizing the length of new hole to be drilled prior to making a

wiper trip. Normally, the first wiper trip will be made 24 hours The wellsite drilling engineer plays a primarily role in the

after drilling out the casing shoe. This wiper trip, along with the implementation of the hole cleaning program. The drilling

divergence/convergence trends, will act as a basis to assess the engineer is responsible for:

frequency of subsequent wiper trips.

428

SPWIADC 29381 Guild, G.J., Wassenborg, M. J., Wallace, I. M. 5

Table 1- Torque and Drag Spreadsheet, SM$K Ti2, i2 i/4 Inch i-ioie Section----

De th Act;U PrcnJPU AdJO PradtSO ActJRot PradtRot Act OBlt-tfD Torque Incim Azim MW Comments

13299 195 187 110 102 145 131 17900 78.6 213.7 i 4.5 Good cutting return, 100% Rotary

13388 191 187 112 102 148 131 ...... 78.0 212.6 14.5 100% Rotary, good heavy cuttings

13466 194 166 113 102 143 132 17900 77.6 213.7 14.5 Side 30’, Rotary drill 60

13561 196 190 113 102 145 132 17100 77.5 213.6 14.5 100% rotary, 900 gpm, good cuttings

,36741,95,9, I ,,4103 I 147133117900 I 77.0 12t4.21 14.5 lloo%rohVs9~gPm90~W~~

13768 192 192 111 103 149 133 17900 76.6 213.7 14.5 100% rotary, good cuttings

13662 193 193 110 103 149 134 16400 76.7 213.5 14.5 100% rotety, good cuttings

13954 195 194 111 104 150 134 17900 76.4 214.5 14.5 Side 25’ tor azimuth, Rotary drill 65’,

Note: PrWtcted and actual weights do not include the weigM of Ihe bloeka.

.) Gathering the torque and drag data from the driller.

2) Running the drag program to compute the predicted

drill string weights.

3) Comparing the predicted and actuals.

4) Keeping the drilling foreman, driller, mud engineer,

and directional driller informed of down-hole conditons.

Depending on the penetration rate, this effort will be a full time job.

In addition, if the average penetration rate is above 100 ftlhr, 24

hour wellsite drilling engineering support is required.

As a part of the wellsite drilling engineer’s duties, a spread sheet

of recorded parameters for each connection is kept. As shown by

table 1, this spread sheet includes the following values: measured

depth, actual and predicted pick up weight, actual and predicted

slack off weight, actual and predicted rotating off bottom weight,

actual off bottom torque, inclination, azimuth, mud weight and

comments. To gather this information the drilling engineer

travels between critical wellsite ‘information points’ on every

connection- from the driller to the mud logger to the shaker hand

to the mud engineer. Although this may seem like a Iabour

intensive exercise, for a critical extended reach well it is value

added in several respects:

1) The drilling engineer, who plays a key role in evaluating the

results of the hole cleaning program, maintains an in-depth

understanding of down-hole conditions.

2) The act of gathering this information stimulates discussion

between personnel at these critical wellsite information points.

This, in turn, helps to maintain a high level of awareness with

respect to down-hole conditions by these personnel.

The Role of the Shaker Hand

The hole cleaning program involves more than just gathering drill

string weight information. In essence, anything that can be done

to improve rig crew awareness of down-hole conditions is value

added. Monitoring the rate of cuttings returned over the shaker by

the shaker hand is another method of maintaining hole cleaning

awareness. The rate of cuttings returned is an indicator of how well

the hole is cleaning.

Monitoring the rate of cuttings returned is relatively simple but

effective. The basic process is to record the time it takes to fill a

viscosity cup with cuttings. Because this information is relative,

this recording is made from the same place on the same shaker each

time. Depending on the penetration rate, this value is recorded by

the shaker hand every 15to 20 minutes just before or after recording

the mud weight. Each time this check is done it is reported to the

429

6 Hole Cleaning Program for Extended Reach Wells SPWIADC 29381

Table 2- Monitoring Cuttings Returned and Volume of Mud System While Drilling, 12 1/4 Inch Hole, SEER T12

De thv

(1) Cuttings Return (2) Voiume Drop of CommentsDri ied Rate (See) Active Mud System(ft4fD) (bbi)

15637-727 6 15 100% Rotary dril, good cuttrngs return

15727-816 20 4 Siide 60’ of stand

15816-911 6 15 100% Rotary dril

15911-16007 7 13 100% Rotary dril

16559-652 15 5 Siide 30’ of stand

16652-746 5 17 100% rotary drii, ROP increasing

Notes:

(1) Time taken to fiii vise cup with cuttings from shaker

(2) Voiume drops of active mud system whiie driiiing stand down

drilier. Conveying this information keeps the driller aware of how be removed and mud volume would not drop as much. The mud

the hole is cleaning under various operating modes: while slide or logger will record the mud volume after each connection and report

rotary driiling, while pumping a sweep, while circulating on the value to the driller. This adds to the driller’s awarness of how

bottom and while circulating at reduced pump rates. well the hole is cleaning.

The Role of the Mud Logger Monitoring the trends of cuttings return rate and volume of the

active mud system was done on SEERT12. A partial listing of this

The mud logged plays significant role in determining wellbore data is shown in Tabie Z This data shows that the rate of cuttings

conditions by tracking trip and connection gas, cuttings description returned and the active mud system volume are dependent on the

and plotting formation pressure. However, the mud logger can also operating mode. For instance, from 15,637-15,727 ft MD, the rate

assist in maintaining hole cleaning awareness by monitoring the of cuttings returned -6 seconds per viscosity cup, is relative good

reduction in the active mud system voiume as the hole is drilled. and the volume drop of the active mud system corresponds to nearly

Monitoring volume is most effective if: 1) there are no down-hole gauge hole. However, from 15,727 to 15,816 ftMD it takes a ionger

iosses, 2) there is an understanding of how much whole mud is iost period to fill the viscosity cup with cuttings -20 seconds, and the

through the soiids controi equipment, 3) wiioie mud additions to redu~ti~ii iii mud ~~i~in~ k fi~t ss g~etii. This ~~iie~-~fid~ t~ a

the active system are carefully monitored, and 4) the welibore period when most of the stand is being drMed in siiding mode and

remains a relatively uniform diameter, i.e., no excessive washouts the drill string is not being rotated. Because of this, the cuttings do

If these conditions are satisfied then a drop in the volume of the not get agitated into the flow regime and transport to the surface is--. :..-—..2 _..e. _ ... -..1A L- ..- .,. ●I.- :.. ,. . . . . :.. h..l.s ..,.1 ...,.,,, ; aZW1lVC IIIUU SySLi%l WUUIU uc duc L(J UK, lllb,~casc III llUIG VUIU1llG, I. G.,

#f&.:e& ‘TW.- ~-%wniAam i. .- n+id h-t-k tn fh- Arillar whit-hAllLO1111U11116LUW11la s-p”. - -“- .“ “.” w...”. .. ...”..

the replacement of cuttings removed from the hole with mud. In increases the awareness with respect to the effects of sliding on hole

situations where hole cieaning is poor, not as many cuttings would cieaning.

430

SPIMADC 29381 Guild, G.J., Wassenborg, M. J., Wallace, I. M. 7

Feet Per Day

1400

1300

1200

1100

1000

900

800

700\

600

500

400

300

200

100

0Hole 17 112” 12 114” Hole 16” 12 114’ Hole 16° 12 1149

Arbroath ArbroathT14

North EverestT19 SEER T12

Measured Depth (feet)

Fig. 5- Drilling progress for the intermediate hole sections of Arbroath T14, T19, and North Everest SEER T12.

Table 3- Drilling Performance in the Intermediate Hole sections

r1

1

Im

Distance between I I Iwiper trips (ft) 522 1124 1390 1114 2065 2408

Back reaming tripsbefore casing point o 3 0 2 0 1

Stuck pipeoccurrences o 2 0 0 0 0

Hole: 17 1/2” 12 1/4” Hole: 16” 121/4” Hole: 16” 12 114”

A r~lo$t h Arbroath N Q& ~vf~2stT19

Obviously, other rig crew members will have hole cleaning DriUingPerformanceindicators normally used for conventional drilling. However,

monitoring of torque and drag parameters, the rate of cuttings The hole cleaning program was refined over the course of three~tlm.e~ OYW Lhe shadw and the volume of the active mud system Amoco UK extended reach wells. This program was used mainly

per stand drilled are additional hole cleaning efforts that Amoco in the intermediate hole sections of these wells. Hole cleaning was

UK has found to be effective when drilling extended reach wells. never a problem in the tophole section of these wells; therefore, the

431

8 Hole Cleaning Program for Extended Reach Wells SPE/lADC 29381

.acnnt ,,.~~ ;“ A;. -~ -f +a .. Jell A 1.- J.. - ..-. ~- “pK?gWT. w- 1’” -.-11’ “11. p . “, t lW w 11. AIXJ, Uutz Lu lurmaticm fj. U-ridersome conditions, a reduction in off bottom rotating

ledging in the production hole, the agreement between actual and torque may be an indication that the hole is loading up with

predicted pick up and slack off drill string weight W* not * good cuttings.

& Lheintermediate sectk!!l. Th=ri=fnre th~ tnrq~~ ~~~ &~g portt~~. ..-. -.”.”, “.- .“.

of the c!eaning p=garn. W&Q not Iustx! in the prndll~tinn CPP~;fim fif y.... WW”.. ”.. ““w., ”,, “1 Tiie agreement ‘between predicted and actuai &-iiistring

these wells. weight may not be close if there is significant formation ledging. In

this situation, the hole cleaning program may not be possible to use

Figure 5 shows the drilling performance, in terms of feet drilled per in its full form.

day, for the intermediate hole sections of Arbroath T14, T19 and

North Everest SEER T12. Table 3 shows the distance between Nornen&~

wiper trips and backreaming tips before reaching casing point as

well as the number of stuck pipe occurrences. From Arbroath T14

through SEER T12 significant drilling performance was realised.

l%eholeckaningprogramco ntributed to performance by improving

our understanding of how well the hole was being cleaned as it was

being drilled. This understanding allowed us to increase the

distance drilled before making a wiper trip, eliminate hole cleaning

backreaming trips prior toreachingcasing point, optimize circulation

time on connections and maximise penetration rates.

Recommendations and Conclusions

1. Monitoring torque and drags trends, the rate of cuttings

returned and volume reduction of the active mud system as the

hole is drilled provides a good understanding of how well the hole

is being cleaned. This, in turn, helps improve drilling performance.

2. Monitoring torque and drag at the wellsite requires the

support of a wellsite drilling engineer. When penetration rates

exceed 100 fph (average), 24 hour wellsite drilling engineering

support is needed.

3. Monitoring the rate of cuttings returned over the shaker is

a simple but effective way to enhance the understanding of how the

hole is cleaning under various operating modes.

Act -n7im -. . . . . .

bbl -

BHA -

ft -

gpm -

hr -

inc -

inclin -

lbs -

MD -

Mw -

PPt3 -ppf -

pred -

psi -

Pu -

OB -

Rot -

so -

WOB -

Wt -

actual~~:~,,~~~,

barrel

bottom hole assembly

feet or foot

gallons per minute

hour

increase

inclination

pounds

measured depth

mud weight, ppg

pounds per gallon

pounds per foot

predicted

pounds per square inch

pick up

off bottom

Rotate

slack off

weight on bit

weight, lbs or klbs

References4. Monitoring the reduction in the volume of the active mud

system as the hole is being drilled is another means of determining 1. Hemphill, T., Larsen, T.I., “Hole Cleaning Capabilities of Oil-

how the hole is cleaning under various operating modes. based and Water-Based Drilling Fluids: A Comparative

Experimental Study:’ SPE 26328, Presented at the 68th Annual

5. Convergence and divergence trends of pick Up id slack off Technical Conference SpE, Houston Texas, 3-6 Oct. 1993,pg 142.———...

A-i!! W@ we@ ~~i be used as a means to determine hoie

cleaning over a period of time.

432

SPEAADC 29381 Guild, G.J., Wassenborg, M. J., Wallace, I. M.

2. Tomren, P.H., Iyoho, A.W., Azar, J.J., “Experimental Study of

Cuttings Transport in Directional Wells,” SPE Drilling

Engineering, Feb. 1986, pg51.

3. Alfsen, T.E., Heggen, S., Blikra, H., Tjotta, H., “Pushing the

limits for Extended Reach Drilling, New World Record for

Platform Statfjord C, Well C2”, SPE 26350, 68th Annual SPE

Technical Conference and Exhibition, 3-6 October, 1993, Houston,ws.-.

4. Guild, G.J., Jeffrey, J.T.: “Drilling Extended Reach High-

Angle Holes Through Overpressured Shale Formation in the

Central Graben Basin, Arbroath Field, Block 22/17, U.K. North

Sea”, SPE/IADC 25749, February 1993, pg 679-688.

5. Brett, J.F., Beckett, A.D., HoIt, C.A., Smith, D.L.: “Uses and

Limitations of Drill String Tension and Torque Models for

Monitoring Hole Conditions,” SPE Drilling Engineering

(September 1989).

9

6. Johancsik, C.A., Friesen, D.B., Dawson, R.: “Torque and Drag

in Directional Holes-Prediction and Measurement,’’JPT (June

1984), pg 987-992.

433