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US 12,242,011 B2Granted
Method for estimating water saturation in gas reservoirs using acoustic log P-wave and S-wave velocites
AssigneeGoshey Energy Services LLC
InventorSheyore John Omovie
Life of this patent
Estimating the term…
Abstract
The present application relates to new systems and methods of quantifying hydrocarbon saturation using measured acoustic logs. The methods and systems herein can accurately quantify the water saturation and hydrocarbon percentage in a low resistivity low contrast shaly sand reservoir where previous methods would indicate the reservoir was wet. In an embodiment, the disclosed system utilizes acoustic logging equipment or tools and techniques to transmit and/or record acoustic signals. Acoustic logging equipment operates by generating acoustic signals and detecting the acoustic signals after the acoustic signals pass through one or more geologic formations.
Claims17
A system of estimating hydrocarbon saturation of a hydrocarbon reservoir where at least an oil rig is operated to create a first wellbore into the hydrocarbon reservoir, the system comprising:
- an acoustic logging system, comprising:
- a motor and a cable, or a drill bit and at least one drilling pipe;
- and
- an acoustic measuring device positioned horizontally adjacent to the hydrocarbon reservoir within the first wellbore;
- a processor, wherein the processor is configured to:
- measure a compressional wave of a hydrocarbon-bearing interval within a first subsurface reservoir;
- measure a shear wave of the hydrocarbon-bearing interval across the first subsurface reservoir;
- determine a velocity of the compressional wave of the hydrocarbon-bearing interval;
- determine a velocity of the shear wave of the hydrocarbon-bearing interval;
- determine a fully brine-saturated trend for the hydrocarbon reservoir;
- determine a fully hydrocarbon-saturated trend for the hydrocarbon reservoir;
- determine a water saturation of the hydrocarbon reservoir based on a deviation of the velocity of the compressional wave of the hydrocarbon-bearing interval and the velocity of the shear wave of the hydrocarbon-bearing interval from the fully brine-saturated trend and the fully hydrocarbon-saturated trend;
- and
- estimate the hydrocarbon saturation of the hydrocarbon reservoir based on the determined water saturation, wherein the fully brine-saturated trend and the fully hydrocarbon-saturated trend are determined in terms of velocity ratio and shear sonic log or velocity ratio and compressional sonic log,
- wherein the determined water saturation is based on:
- Swt
- =
- ❘
- "\[LeftBracketingBar]"
- a
- 0
-
- x
- +
- b
- 0
-
- y
- +
- c
- 0
- ❘
- "\[RightBracketingBar]"
- a
- 0
- 2
- +
- b
- 0
- 2
- ❘
- "\[LeftBracketingBar]"
- a
- 1
-
- 0
-
- 0
-
- x
- +
- b
- 1
-
- 0
-
- 0
-
- y
- +
- c
- 1
-
- 0
-
- 0
- ❘
- "\[RightBracketingBar]"
- a
- 1
-
- 0
-
- 0
- 2
- +
- b
- 1
-
- 0
-
- 0
- 2
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity;
- b0 is a coefficient of shear acoustic log (DTS), c0 is an intercept of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTS, c100 is an intercept of the fully brine-saturated trend, and Swt is a water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of a bulk modulus (KB), b0 is a coefficient of a shear modulus G, c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of KB, b100 is a coefficient of G;
- c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp where Vp is a velocity of a compressional wave, b0 is a coefficient of Vs where Vs is a shear wave velocity, c0 is a coefficient of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp where Vp is a velocity of a compressional wave, b100 is a coefficient of Vs where Vs is a shear wave velocity, c100 is a coefficient of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b0 is a coefficient of compressional acoustic log (DTC), c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTC, c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth.
91 more elements
A method of estimating hydrocarbon saturation of gas and oil reservoirs, the method comprising:
- creating a wellbore in a hydrocarbon reservoir;
- moving an acoustic measuring device to a position within the hydrocarbon reservoir;
- measuring a compressional wave of a hydrocarbon-bearing interval within a first subsurface reservoir;
- measuring a shear wave of the hydrocarbon-bearing interval across the first subsurface reservoir;
- determining a velocity of the compressional wave of the hydrocarbon-bearing interval;
- determining a velocity of the shear wave of the hydrocarbon-bearing interval;
- determining a fully brine-saturated trend for the hydrocarbon reservoir;
- determining a fully hydrocarbon-saturated trend for the hydrocarbon reservoir;
- determining a water saturation of the hydrocarbon reservoir based on a deviation of the velocity of the compressional wave of the hydrocarbon-bearing interval and the velocity of the shear wave of the hydrocarbon-bearing interval from the fully brine-saturated trend and the fully hydrocarbon-saturated trend;
- and
- estimating the hydrocarbon saturation of the hydrocarbon reservoir based on the determined water saturation, wherein the fully brine-saturated trend and the fully hydrocarbon-saturated trend are determined in terms of velocity ratio and shear sonic log or velocity ratio and compressional sonic log,
- wherein the determined water saturation is based on:
- Swt
- =
- |
- a
- 0
-
- x
- +
- b
- 0
-
- y
- +
- c
- 0
- |
- a
- 0
- 2
- +
- b
- 0
- 2
- |
- a
- 100
-
- x
- +
- b
- 100
-
- y
- +
- c
- 100
- |
- a
- 100
- 2
- +
- b
- 100
- 2
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity;
- b0 is a coefficient of shear acoustic log (DTS), c0 is an intercept of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTS, c100 is an intercept of the fully brine-saturated trend, and Swt is a water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of a bulk modulus (KB), b0 is a coefficient of a shear modulus G, c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of KB, b100 is a coefficient of G;
- c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp where Vp is a velocity of a compressional wave, b0 is a coefficient of Vs where Vs is a shear wave velocity, c0 is a coefficient of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp where Vp is a velocity of a compressional wave, b100 is a coefficient of Vs where Vs is a shear wave velocity, c100 is a coefficient of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b0 is a coefficient of compressional acoustic log (DTC), c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTC, c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth.
64 more elements
A non-transitory computer readable medium storing instructions that, when executed by a processor, cause the processor to perform operations comprising:
- measure a compressional wave of a hydrocarbon-bearing interval within a first subsurface reservoir;
- measure a shear wave of the hydrocarbon-bearing interval across a second subsurface reservoir;
- determine a velocity of the compressional wave of the hydrocarbon-bearing interval;
- determine a velocity of the shear wave of the hydrocarbon-bearing interval;
- determine a fully brine-saturated trend for a hydrocarbon reservoir;
- determine a fully hydrocarbon-saturated trend for the hydrocarbon reservoir;
- determine a water saturation of the hydrocarbon reservoir based on a deviation of the velocity of the compressional wave of the hydrocarbon-bearing interval and the velocity of the shear wave of the hydrocarbon-bearing interval from the fully brine-saturated trend and the fully hydrocarbon-saturated trend;
- and
- estimate a hydrocarbon saturation of the hydrocarbon reservoir based on the determined water saturation, wherein the fully brine-saturated trend and the fully hydrocarbon-saturated trend are determined in terms of velocity ratio and shear sonic log or velocity ratio and compressional sonic log,
- wherein the determined water saturation is based on:
- Swt
- =
- |
- a
- 0
-
- x
- +
- b
- 0
-
- y
- +
- c
- 0
- |
- a
- 0
- 2
- +
- b
- 0
- 2
- |
- a
- 100
-
- x
- +
- b
- 100
-
- y
- +
- c
- 100
- |
- a
- 100
- 2
- +
- b
- 100
- 2
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity;
- b0 is a coefficient of shear acoustic log (DTS), c0 is an intercept of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTS, c100 is an intercept of the fully brine-saturated trend, and Swt is a water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of a bulk modulus (KB), b0 is a coefficient of a shear modulus G, c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of KB, b100 is a coefficient of G;
- c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp where Vp is a velocity of a compressional wave, b0 is a coefficient of Vs where Vs is a shear wave velocity, c0 is a coefficient of the fully hydrocarbon-saturated trend;
- a100 is a coefficient of Vp where Vp is a velocity of a compressional wave, b100 is a coefficient of Vs where Vs is a shear wave velocity, c100 is a coefficient of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth;
- or
- wherein a0 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b0 is a coefficient of compressional acoustic log (DTC), c0 is the intercept of the fully hydrocarbon-saturated trend, a100 is a coefficient of Vp/Vs where Vp is a velocity of a compressional wave and Vs is a shear wave velocity, b100 is a coefficient of DTC, c100 is the intercept of the fully brine-saturated trend, and Swt is water saturation fraction of a total pore space at each lateral depth.
62 more elements
Dependencies are inferred from the claim text.