IP Library › Granted Patent US 12,644,878
Granted Patent B2
US 12,644,878 · App. 17/775,720 · Granted Jun 2, 2026

Method for estimating hydrocarbon saturation of a rock

Inventors: Nishank Saxena (Houston, TX); Amie Marie Hows (Houston, TX); Matthias Appel (Houston, TX); John Justin Freeman (Houston, TX)
G01N33/241G01N15/088G06T7/0004G01N2015/0846G06T2200/04
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Quick Facts
Patent No.
US 12,644,878
App. No.
17/775,720
Granted
Jun 2, 2026
Kind
B2
Abstract

The present invention provides a method for estimating hydrocarbon saturation of a hydrocarbon-bearing rock from a resistivity log and a rock image. The image is segmented to represent either a pore space or solid material in the rock. An image porosity is estimated from the segmented image, and a corrected porosity is determined to account for the sub-resolution porosity missing in the image of the rock. A corrected cementation exponent of the rock is determined from the image porosity and the corrected porosity and is used to estimate the hydrocarbon saturation. A backpropagation-enabled trained model can be used to segment the image. A backpropagation-enabled method can be used to estimate the hydrocarbon saturation using an image selected from a series of 2D projection images, 3D reconstructed images and combinations thereof.

Claims (16)

1 . A method for estimating hydrocarbon saturation of a hydrocarbon-bearing rock from a resistivity log and a rock image, comprising:

obtaining a resistivity log and a density log for a field having a hydrocarbon-bearing formation;

obtaining a 3D image of a rock from the hydrocarbon-bearing formation in the field, wherein the 3D image is comprised of a plurality of voxels and the 3D image has a resolution;

processing the 3D image to segment the 3D image by selecting each voxel of the 3D image to represent either a pore space in the rock or solid material in the rock;

estimating an image porosity of the rock from the segmented 3D image, the image porosity lacking a sub-resolution porosity of the rock;

determining a corrected porosity adapted to account for the sub-resolution porosity of the rock;

estimating a corrected cementation exponent of the rock from the image porosity and the corrected porosity of the rock;

estimating the hydrocarbon saturation of the hydrocarbon-bearing rock using the corrected cementation exponent; and

converting the resistivity log to a continuous saturation profile using the estimated hydrocarbon saturation and the density log.

2 . The method of claim 1 , wherein the 3D image of the rock is obtained by x-ray computer tomography.

3 . The method of claim 1 , wherein the step of estimating the hydrocarbon saturation comprises determining a formation water resistivity and a saturation exponent.

4 . The method of claim 1 , wherein the rock is obtained from a hydrocarbon-bearing formation comprised of sandstone, carbonate, shale and combinations thereof.

5 . The method of claim 1 , wherein the corrected porosity of the rock is determined by laboratory measurement.

6 . The method of claim 1 , wherein the corrected porosity of the rock is determined by deriving a non-wetting liquid capillary pressure curve from the segmented 3D image of the rock; and determining the corrected porosity from the segmented 3D image and the non-wetting liquid capillary pressure curve.

7 . The method of claim 6 , wherein the non-wetting liquid capillary pressure curve is derived from the segmented 3D image of the rock at pressures of up to an image-limited pressure, where the image-limited pressure is the minimum pressure that can be applied on the non-wetting liquid to overcome the capillary pressure of the narrowest pore throat distinguishable from the segmented 3D image of the rock.

8 . The method of claim 1 , wherein the 3D image is obtained from a cloud-based tool adapted to store and process 2D projection images from a pore-scale imaging technology.

Assignments (1)
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Nov 3, 2022
From: SAXENA, NISHANK; HOWS, AMIE MARIE; APPEL, MATTHIAS; FREEMAN, JOHN JUSTIN
To: SHELL USA, INC.
Reel/Frame 061640/0072 →
Continuity (2)
Provisional Application 62947091 · Dec 12, 2019
Related Publication 20220404330A1 · Dec 22, 2022
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