Chapter 5 Determination of Rw - New Mexico Institute of Mining
Transcript of Chapter 5 Determination of Rw - New Mexico Institute of Mining
Chapter 5
Determination of Rw
Lecture notes for PET 370
Spring 2012
Prepared by: Thomas W. Engler,
Ph.D., P.E.
Determination of Rw
1. Archie’s Equation
a. if water zone is present.
b. Rwa Approach
c. Resistivity - Porosity Crossplots
2. Laboratory
a. Direct measurement of representative
water sample.
b. Chemical analysis of water sample.
3. Databases
a. Published regional water catalogs
b. online:http://octane.nmt.edu/waterquality/
4. SP log
5. Guess?
Methods
F
oR
wR
k
SSP
mfeR
weR 10*
Determination of Rw
Preliminary Concepts
Total conductivity is influenced by:
– porosity
– water saturation
– salinity
– salt composition
– temperature
– shale content
– metallic minerals; e.g., pyrite
Water
conductivity
metXshXF
nwSwC
tC
Determination of Rw
Preliminary Concepts
Temperature Effects
ionic conductivity - as temp. increases the
conductivity increases. Why?
Salinity Effects
As salinity increases the conductivity will
increase.
Solution ppm NaCl resistivity,-m
oil or gas - 1.0 E6
Potable water 500 10.0
Fresh mud filtrate < 5,000 1.0 - 5.0
Sea water 35,000 0.2
Salt mud filtrate 75,000 0.1
Saturated salt water 250,000 0.04
Determination of Rw
How to determine formation temperature?
During logging operations record the maximum temperature
(TTD) at the bottom of the well (DTD).
Assume a linear geothermal gradient, (gG), {deg.F/100 ft}
Region of Diurnal and
Annual Variations
To Ta
TEMPERATURE
DE
PT
H
100’
gG
{F/100’}
TTD, DTD
Tf, Df
oT
TDD
fD
)o
TTD
(Tf
T
Determination of Rw
How to determine formation temperature?
Near surface temperature, (To), is given regionally by:
Gulf Coast 80 deg. F
Oklahoma 60
California 60
Permian Basin 60
Rocky Mtns. 50
Alberta 35
Determination of Rw
Location To, C
Ankara, Turkey 6.7
Aswan, Egypt 26.7
Aberdeen, Scotland 8.9
Bogota, Columbia 14.3
Bombay, India 27.1
Calgary, Alberta 5.4
Caracas, Venezuela 20.5
Changha, China 18.0
Gabon, Africa 26.0
Great Yarmouth, England 8.9
Location To, C
Jakarta, Indonesia 26.7
Lima, Peru 20.0
Mendoza, Argentina 16.0
Natal, Brazil 23.0
Perth, Australia 18.0
Prince George, B.C. 3.6
Rio De Janeiro, Brazil 23.0
Santa Cruz, Bolivia 15.0
Siberia (west), Russia -4.0
Trinidad, W.I. 29.7
How to determine formation temperature?
Determination of Rw
1. Archie’s Equation
a. if water zone is present.
b. Rwa Approach
c. Resistivity - Porosity Crossplots
2. Laboratory
a. Direct measurement of representative
water sample.
b. Chemical analysis of water sample.
3. Databases
a. Published regional water catalogs
b. online:http://octane.nmt.edu/waterquality/
4. SP log
5. Guess?
Methods
F
oR
wR
k
SSP
mfeR
weR 10*
Determination of Rw
Direct measurement
Obtain water sample and corresponding temperature.
Representative sample:
Pumping well with high WOR
Flowing well with high WOR
Drill stem test
Not Useful:
Flowing well with high GOR
Condensate - gas well
Well with casing leak
Tank bottoms
Determination of Rw
How to determine resistivity if a chemical
composition is available?
Calculate equivalent NaCl concentration by
using ion multipliers.
Use salinity - temperature - resistivity
relationships to find Rw.
Example
Ion ppm multiplier Equiv NaCl
ppm Na+ and Cl- 25,000 1.00 25,000
CO3- 2,000 0.42 840
SO4++ 5,000 0.40 2,000
HCO3- 10,000 0.23 2,300
Mg++ 4,000 0.93 3,720
TDS = 46,000 33,860
T = 200 deg. F => Rw = ohm-m
Determination of Rw
How to determine resistivity if a chemical
composition is available?
Empirical Ion Multiplier Chart
Schlumberger
Determination of Rw
1. Archie’s Equation
a. if water zone is present.
b. Rwa Approach
c. Resistivity - Porosity Crossplots
2. Laboratory
a. Direct measurement of representative
water sample.
b. Chemical analysis of water sample.
3. Databases
a. Published regional water catalogs
b. online:http://octane.nmt.edu/waterquality/
4. SP log
5. Guess?
Methods
F
oR
wR
k
SSP
mfeR
weR 10*
Determination of Rw
waR
wR
wS
:by saturation water Determine
)minimum(waRwR
:find zones, of series afor Calculate
F
tR=waR
thusincrease; Rt will but the
same theis iprelationsh F thezone, HC ain If
F
)oRor(tR
wR
then100%), = (Sw zone water ain If
F
tR2wS
wR
:Equation sArchie' Rearrange
Rwa Technique
Requirements:
1. Rw is constant
2. Lithology is constant
3. A water zone exists and is identifiable
Procedure:
Determination of Rw
Rwa Technique Example
Strawn Sandstone Evaluation Rwa Approach
average Rwa = Sw =
Interval Ca, mmho/m Rt, ohm-m t,microsec/ft porosity F Rt/F (Rw/Rwa)1/2
3562-64 110 9.1 65 0.097 85.9 0.106 0.942 tight
3564-66 90 11.1 76 0.179 25.4 0.438 0.463 pay
3566-68 90 11.1 71 0.143 39.5 0.281 0.578 pay
3568-70 100 10.0 62 0.072 155.1 0.064 1.000 tight
3570-72 125 8.0 70 0.136 43.9 0.182 0.718 tight/wet
3572-74 130 7.7 76 0.179 25.4 0.303 0.557 pay
3574-76 125 8.0 72 0.151 35.7 0.224 0.648 wet
3576-78 125 8.0 68 0.121 55.6 0.144 0.808 tight
3578-80 120 8.3 70 0.136 43.9 0.190 0.704 wet
3580-82 115 8.7 71 0.143 39.5 0.220 0.653 wet
3582-84 115 8.7 70.5 0.140 41.6 0.209 0.671 wet
3584-86 120 8.3 72 0.151 35.7 0.233 0.635 wet
3586-88 120 8.3 71 0.143 39.5 0.211 0.667 wet
3588-90 130 7.7 71 0.143 39.5 0.195 0.695 wet
3590-92 145 6.9 73 0.158 32.6 0.212 0.666 wet
3592-94 200 5.0 70 0.136 43.9 0.114 0.908 shaly
3594-96 270 3.7 75 0.172 27.4 0.135 0.834 shaly
3596-98 280 3.6 74.5 0.168 28.6 0.125 0.867 shaly
3598-3600 260 3.8 71 0.143 39.5 0.097 0.982 wet
3600-02 280 3.6 73 0.158 32.6 0.110 0.926 wet
3602-04 320 3.1 75 0.172 27.4 0.114 0.908 wet
3604-06 355 2.8 74 0.165 29.8 0.094 0.997 wet
3606-08 360 2.8 76 0.179 25.4 0.110 0.926 wet
3608-10 350 2.9 75 0.172 27.4 0.104 0.950 wet
3610-12 340 2.9 74 0.165 29.8 0.099 0.976 wet
3612-14 350 2.9 74 0.165 29.8 0.096 0.990 wet
3614-16 325 3.1 74 0.165 29.8 0.103 0.954 wet
3616-18 275 3.6 72 0.151 35.7 0.102 0.961 wet
3618-20 200 5.0 73 0.158 32.6 0.154 0.782 wet
3620-22 120 8.3 66 0.105 73.3 0.114 0.909 wet
Rw=0.094
depth h Sw h hSw
3564-66 2 0.179 0.463 0.358 0.166
3566-68 2 0.143 0.578 0.286 0.165
3572-74 2 0.179 0.557 0.358 0.199
6 1.002 0.530
average porosity in pay zones = 0.167 Area = 40 acres
average Sw in pay zones = 0.529 Boi = 1.5 rbbl/stb
OIP = 97,551 stb
Determination of Rw
1. Archie’s Equation
a. if water zone is present.
b. Rwa Approach
c. Resistivity - Porosity Crossplots
2. Laboratory
a. Direct measurement of representative
water sample.
b. Chemical analysis of water sample.
3. Databases
a. Published regional water catalogs
b. online:http://octane.nmt.edu/waterquality/
4. SP log
5. Guess?
Methods
F
oR
wR
k
SSP
mfeR
weR 10*
Determination of Rw
Resistivity – Porosity Crossplots
Pickett Plot
Rearrange Archie’s Equation:
wSlogn)
waRlog(logm
tRlog
Determination of Rw
Resistivity – Porosity Crossplots
Pickett Plot Example
Pickett Plot
y = 0.3007x-0.5267
R2 = 0.7674
0.01
0.10
1.00
0.10 1.00 10.00 100.00
Rt,ohm-m
Po
rosit
y
aRw=0.10
Rw=0.12
m=1/.5267=1.90
Sw=50%
Results:
m = 1.90
Rw = 0.12 ohm-m
Determination of Rw
Resistivity – Porosity Crossplots
Hingle Plot
m/1
waR
n
wSm/1
]t
R[
Rearrange Archie’s Equation
Determination of Rw
Resistivity – Porosity Crossplots
Hingle Plot Example
Hingle Plot, m=1.90
y = 3.4858x
R2 = 0.9836
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.00 0.05 0.10 0.15 0.20
Porosity
Rt-
1/m
Sw = 50%
At= 10% y = 0.35
Ro = 7.4 ohmm
F = 64
Rw = 0.115 ohmm
OOIP = 118 Mstb