Algo del petroleo
Schlumberger
Rweq Determination from ESSP
Clean formations
SP-1
This chart and nomograph calculate the equivalent formation water resistivity, R weq, from the static spontaneous potential, E SSP, measurement in clean formations. Enter the nomograph with ESSP in mV, turning through the reservoir temperature in °F or °C to define the R mfeq /R weqratio. From this value, pass through the R mfeq value to define R weq. For predominantly NaCl muds, determine R mfeq as follows: a. If R mf at 75°F (24°C) is greater than 0.1 ohm-m, correct R mf to formation temperature using Chart Gen-9, and use R mfeq = 0.85 R mf. b. If R mf at 75°F (24°C) is less than 0.1 ohm-m, use Chart SP-2 to derive a value of R mfeq at formation temperature.
Example: SSP =100 mV at 250°F R mf = 0.70 ohm-m at 100°F or 0.33 ohm-m at 250°F Therefore, R mfeq = 0.85 × 0.33 = 0.28 ohm-m at 250°F R weq = 0.025 ohm-m at 250°F E SSP = –K c log(R mfeq /R weq ) K C = 61 + 0.133 T°F K C = 65 + 0.24 T°C
Rweq (ohm-m) 0.001
SP
Rmfeq /Rweq 0.3 0.4 0.5 0.6 0.8 1 0.3 0.4 0.6 0.8 1 0.02 0.04 0.06 2 aw /amf or Rmfe /Rwe 3 4 5 6 8 10
F 0° F 50 0° 40 0°F C C 0° 30 25 00° C 0°F2 0° 20 15 0°C °F 10 100 C 50° 0°C
0.005
Rmfeq (ohm-m) 0.01
0.01
0.02
2
0.1 0.2
0.05
4 6
0.4 0.6 1 0.1
8 10 2 4 6 20 10 20 40 40 60 100 2.0 1.0 0.5 0.2
20 30 40 50 +50 0 –50 Formation temperature
–100
–150
–200
ESSP, static spontaneous potential (mV)
© Schlumberger
2-5
Gamma Ray and Spontaneous Potential
Schlumberger
Rw versus Rweq andFormation Temperature
SP-2 (English)
0.001 500°F 400°F 0.002 300°F 200°F 150°F 0.005 100°F 75°F 0.01 Saturation 0.02 R weq or R mfeq (ohm-m)
SP
0.05
0.1
0.2
500° F 400 °F 300 °F 200 °F 150 °F 100 °F 75° F
0.5
F 5° t7 la aC N
1.0
2.0 0.005
0.01
0.02 0.03
0.05
0.1
0.2
0.3
0.5
1.0
2
3
4 5
R w or Rmf (ohm-m)
© Schlumberger
Thesecharts convert equivalent water resistivity, R weq , from Chart SP-1 to actual water resistivity, R w. They may also be used to convert R mf to R mfeq in saline muds. Use the solid lines for predominantly NaCl waters. The dashed lines are approximate for “average” fresh formation waters (where effects of salts other than NaCl become significant). The dashed portions may also be used for gyp-base mudfiltrates.
Example: R weq = 0.025 ohm-m at 120°C From chart, R w = 0.031 ohm-m at 120°C Special procedures for muds containing Ca or Mg in solution are discussed in Reference 3. Lime-base muds usually have a negligible amount of Ca in solution; they may be treated as regular mud types.
2-6
Gamma Ray and Spontaneous Potential
Schlumberger
Rw versus Rweq and Formation Temperature
SP-2m(Metric)
0.001 250°C 200°C 0.002 150°C 100°C 75°C 0.005 50°C 25°C Saturation 0.02 R weq or R mfeq (ohm-m)
SP
0.01
0.05
0.1
0.2
250° C 200 °C 150 °C 100 ° 75° C C 50° C 25° C
0.5
C 5° t2 la aC N
1.0
2.0 0.005
0.01
0.02 0.03
0.05
0.1
0.2
0.3
0.5
1.0
2
3
4 5
R w or Rmf (ohm-m)
© Schlumberger
2-7
Gamma Ray and SpontaneousPotential
Schlumberger
SP Correction Charts
For representative cases
SP-3
No invasion R xo = 0.2 R t Rs =1 Rm
1.0
1 52 10 20
Invasion, di /dh = 5 R xo = R t
1.0
0.1 0.2 0.5 1 2 5
R xo = 5 R t
1.0
0.5 21 5 10
1.0
0.8
0.8
0.8
0.8
SP
ESP /ESPcor
0.6
0.6
50
0.5 1
0.6
10 20
0.6
20
0.4 0.2
0.4 0.2
2 5 10 20 50
0.4 0.2
0.4
50
100200
50
0.2
100
100 200
R t /Rm
Rxo /Rm
100
Rxo /Rm
200
Rxo /Rm
40 30 20 15 10 7.5
5
40 30 20 15 10 7.5
5
40 30 20 15 10 7.5 1.0
5
40 30 20 15 10 7.5 1.0
1 5 2
5
Rs =5 Rm
h/dh
1.0
5 10 2
h/dh
1.0
0.2 0.5 1 2
0.8
20
0.8
0.5 1
0.8
5 10 20
0.8
10 20
ESP /ESPcor
0.6
50
0.6
2 5
0.6
0.6
0.4...
Regístrate para leer el documento completo.