Cha Ch apter ter 5 D eter ter min mi n atio ti on of R w
Lecture notes for PET 370 Spring 2012 Prepared by: Thomas W. Engler, Ph.D., P.E.
Determination of R w Methods
1.
Archie’s Equation
R a. if water zone is present. R o w F b. Rwa Approach c. Resistivity - Porosity Crossplots
2.
Laboratory a. Direct measurement of representative water sample. b. Chemical analysis of water sample. sample.
3.
Databases a. Published regional water catalogs b. online:http://octane.nmt.edu/waterquality/ online:http://octane.nmt.edu/waterquality/
4.
SP log
R 5.
we
Guess?
Rmfe *10 mf e
SSP k
Determination of R w Preliminary Prelimin ary Concepts
Total conductivity is influenced by: – porosity porosity – water water saturation – salinity salinity – salt salt composition
Water conductivity
– temperatur te mperaturee – shale shale content – metallic metallic minerals; e.g., pyrite
Ct
n C w Sw F
X sh X met
Determination of R w Preliminary Prelimin ary Concepts
Temperature emperature 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 R w How to determine formation temperature? During logging operations record the maximum temperature (TTD) at the bottom of the well (D TD). Assume a linear geothermal gradient, (g G), {deg.F/100 ft}
TEMPERATURE Ta To Region of Diurnal and Annual Variations
100’ gG {F/100’}
H T P E D
Tf , Df
T (T f TD
To )
D D
f
TD
To
TTD, DTD
Determination of R w How to determine formation temperature? Near surface temperature, temperature, (To), (To), is given given regionally regionally by: Gulf Coast 80 deg. F Oklahoma 60 California 60 Permian Basin 60 Rocky Mtns. 50 Alberta 35
Determination of R w How to determine formation temperature? Location Ankara, Turkey Aswan, Egypt Aberdeen, Scotland Bogota, Columbia Bombay, India Calgary, Alberta Caracas, Venezuela Changha, China Gabon, Africa Great Yarmouth, England
To, C 6.7 26.7 8.9 14.3 27.1 5.4 20.5 18.0 26.0 8.9
Location Jakarta, Indonesia Lima, Peru Mendoza, Argentina Natal, Brazil Brazil Perth, Australia Prince George, B.C. Rio De Janeiro, Brazil Santa Cruz, Bolivia Siberia (west), Russia Trinidad, W.I.
To, C 26.7 20.0 16.0 23.0 18.0 3.6 23.0 15.0 -4.0 29.7
Determination of R w
How to determine resistivity at Tf ?
Courtesy of Schlumberger
Determination of R w Methods
1.
Archie’s Equation
R a. if water zone is present. R o w F b. Rwa Approach c. Resistivity - Porosity Crossplots
2.
Laboratory a. Direct measurement of representative water sample. b. Chemical analysis of water sample. sample .
3.
Databases a. Published regional water catalogs b. online:http://octane.nmt.edu/waterquality/ online:http://octane.nmt.edu/waterquality/
4.
SP log
R 5.
we
Guess?
Rmfe *10 mf e
SSP k
Determination of R w 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 R w 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 R w. Example
Ion
ppm
Na+ and ClCO3SO4++ HCO3Mg++ TDS =
25,000 2,000 5,000 10,000 4,000 46,000
multiplier 1.00 0.42 0.40 0.23 0.93
T = 200 deg. F => R w =
Equiv NaCl ppm 25,000 840 2,000 2,300 3,720 33,860
ohm-m
Determination of R w How to determine resistivity if a chemical composition is available?
Empirical Ion Multiplier Chart Schlumberger
Determination of R w Methods
1.
Archie’s Equation
R a. if water zone is present. R o w F b. Rwa Approach c. Resistivity - Porosity Crossplots
2.
Laboratory a. Direct measurement of representative water sample. b. Chemical analysis of water sample sample. 3.
Databases a. Published regional water catalogs b. online:http://octane.nmt.edu/waterquality/ online:http://octane.nmt.edu/waterquality/
4.
SP log
R 5.
we
Guess?
Rmfe *10 mf e
SSP k
Determination of R w
Rwa Te Tech chn n i qu que e
Requirements:
1. Rw is constant 2. Lithology is constant 3. A water zone exists and is identifiable Procedure: Rearrange Archie' s Equation : R w
S2 w R t
F If in a water zone (Sw = 100%), then R t (or R o ) R w F If in a HC zone, the the F relationship is the the same but the the Rt will wi ll increase; thus R t R wa = F Calculate for a series of zones, find : R w R wa ( minimum ) Determine water saturation by : Sw
R w R wa
Determination of R w Rwa Te Techn chnii que E x ampl ample e
Determination of R w Rwa Te Techn chnii que E x ampl ample e Strawn Sandstone Evaluation
Rwa Approach
Interval Ca, mmho/m Rt, ohm-m t, t,microsec/ft 3562-64 110 9.1 65 3564-66 90 11.1 76 3566-68 90 11.1 71 3568-70 100 10.0 62 3570-72 125 8.0 70 3572-74 130 7.7 76 3574-76 125 8.0 72 3576-78 125 8.0 68 3578-80 120 8.3 70 3580-82 115 8.7 71 3582-84 115 8.7 70.5 3584-86 120 8.3 72 3586-88 120 8.3 71 3588-90 130 7.7 71 3590-92 145 6.9 73 3592-94 200 5.0 70 3594-96 270 3.7 75 3596-98 280 3.6 74.5 3598-3600 260 3.8 71 3600-02 280 3.6 73 3602-04 320 3.1 75 3604-06 355 2.8 74 3606-08 360 2.8 76 3608-10 350 2.9 75 3610-12 340 2.9 74 3612-14 350 2.9 74 3614-16 325 3.1 74 3616-18 275 3.6 72 3618-20 200 5.0 73 3620-22 120 8.3 66
average porosity 0.097 0.179 0.143 0.072 0.136 0.179 0.151 0.121 0.136 0.143 0.140 0.151 0.143 0.143 0.158 0.136 0.172 0.168 0.143 0.158 0.172 0. 0.165 0.179 0.172 0.165 0. 0.165 0.165 0.151 0.158 0.105
F 85.9 25.4 39.5 155.1 43.9 25.4 35.7 55.6 43.9 39.5 41.6 35.7 39.5 39.5 32.6 43.9 27.4 28.6 39.5 32.6 27.4 29.8 25.4 27.4 29.8 29.8 29.8 35.7 32.6 73.3
Sw = Rwa = 1/2 Rt/F (Rw/Rwa) 0.106 0.942 tight 0.438 0.463 pay 0.281 0.578 pay 0.064 1.000 tight 0.182 0.718 tight/wet 0.303 0.557 pay 0.224 0.648 wet 0.144 0.808 tight 0.190 0.704 wet 0.220 0.653 wet 0.209 0.671 wet 0.233 0.635 wet 0.211 0.667 wet 0.195 0.695 wet 0.212 0.666 wet 0.114 0.908 shaly 0.135 0.834 shaly 0.125 0.867 shaly 0.097 0.982 wet 0.110 0.926 wet 0.114 0.908 wet 0.094 0.997 wet 0.110 0.926 wet 0.104 0.950 wet 0.099 0.976 wet 0.096 0.990 wet 0.103 0.954 wet 0.102 0.961 wet 0.154 0.782 wet 0.114 0.909 wet Rw=0.094
depth 3564-66 3566-68 3572-74
h 2 2 2 6
0.179 0.143 0.179
Sw 0.463 0.578 0.557
average porosity in pay zones = average Sw in pay zones =
h
hSw
0.358 0.286 0.358 1.002
0.167 0.529 OIP =
0.166 0.165 0.199 0.530 Area = Boi =
97,551 stb
40 acres 1.5 rbbl/stb
Determination of R w Methods
1.
Archie’s Equation
R a. if water zone is present. R o w F b. Rwa Approach c. Resistivity - Porosity Crossplots
2.
Laboratory a. Direct measurement of representative water sample. b. Chemical analysis of water sample sample. 3.
Databases a. Published regional water catalogs b. online:http://octane.nmt.edu/waterquality/ online:http://octane.nmt.edu/waterquality/
4.
SP log
R 5.
we
Guess?
Rmfe *10 mf e
SSP k
Determination of R w Resistivity – Por os osii ty Cr os oss spl plots ots
Pickett Plot Rearrange Archie’s Archie’s Equation: log R t
m log log(aR w ) n log Sw
Determination of R w Resistivity – Por os osii ty Cr os oss spl plots ots
Pickett Plot Example Pickett Plot 1.00
Sw=50% aRw=0.10 t i s o 0.10 r o P
Rw=0.12 m=1/.5267=1.90 y = 0.3007x-0.5267 R2 = 0.7674
0.01 0.10
1.00
10.00 Rt,ohm-m
Results: m = 1.90 Rw = 0.12 ohm-m
100.00
Determination of R w Resistivity – Por os osii ty Cr os oss spl plots ots
Hingle Plot Rearrange Archie’s Archie’s Equation 1/ m n 1 / m S w [R ] t aR w
Determination of R w Resistivity – Por os osii ty Cr os oss spl plots ots
Hingle Plot Example Hingle Plot, P lot, m=1.90 m=1.90 0.7 y = 3.4858x 3.4858x
0.6
R2 = 0.9836
0.5 / 0.4 1 t R 0.3
0.2
Sw = 50%
0.1 0.0 0.00
0.05
0.10 Porosity
At = 10%
y= Ro = F= Rw =
0.35 7.4 ohmm 64 0.115 ohmm
OOIP = 118 Mstb
0.15
0.20
Determination of R w
Determination of Rw
References
Bassiouni, Z: Theory, Measurement, Measurement, and Interpretation Interpretation of Well Logs, SPE Textbook Series, Vol. 4, (1994) Chapter 4, Sec 4.5-4.6 Chapter 12, Sec 12.2 Chapter 13
Schlumberger, Schlumberger, Log Interpretation Interpretation Chartbook, (1995)