System and method for modeling a rock sample
A rock modeling method is disclosed. An effective rock property of a rock sample is determined based on a digital rock. Instead of upscaling rock properties, the digital rock is constructed by upscaling relationships and rock physics models of segmented rock materials. Relationships between different scalar, elastic, and petrophysical properties of different segmented rock materials are established at the high-resolution scale where the pore structure is resolved. These relationships are then applied to the same rock material at the macro-scale. Finally, the effective rock properties are computed using Darcy-like solver to get the final values at a representative rock volume. Embodiments allow for performing non-destructive fluid/solid substitution and other reproducible digital experiments to study control factors that affect these relationships within rocks. Accordingly, for unconventional reservoirs, organic matter porosity can be filled with organic matter (kerogen) to build a rock physics model based on kerogen maturity and pore size.
1 . A method for modeling a rock sample, comprising:
drilling a well to obtain the rock sample;
assigning first rock property values of a first rock property to respective grid cells in a digital rock that represents the rock sample, wherein the first rock property values are derived from measurements of the rock sample at a macro-scale;
scanning, via a computed tomography (CT) scanner, the rock sample to obtain a multi-energy CT-scan image;
determining a data volume mineralogy and bulk density from the multi-energy CT-scan image;
identifying a first rock material segment of a plurality of rock material segments of the rock sample based on the data volume mineralogy and bulk density, wherein the first rock material segment comprises pores and grains of a single rock material;
identifying a first digital rock portion of the digital rock corresponding to the first rock material segment of the rock sample;
generating, using a Focused Ion Beam Scanning Electron Microscope, a first high-resolution image of a first representative portion of the first rock material segment;
generating, based on the first high-resolution image of a first representative portion of the first rock material segment, a first rock property relationship between the first rock property and a second rock property, wherein the second rock property is associated with a physical rock structure that is resolved in the first high-resolution image and is not resolved at the macro-scale;
computing, based on the first rock property relationship and the first rock property values in the first digital rock portion, second rock property values of the second rock property for assigning to corresponding grid cells in the first digital rock portion; and
computing, for each grid cell in the first digital rock portion, a second rock property value of the second rock property based on the first rock property relationship and the first rock property values of the grid cell;
determining, based at least on the second rock property values in the first digital rock portion, an effective value of the second rock property of the rock sample; and
producing hydrocarbons, via a production valve, from a production system based on the effective value of the second rock property of the rock sample.
2 . The method of claim 1 , wherein the first rock material segment forms a contiguous volume of the single rock material.
3 . The method of claim 1 , wherein generating the first rock property relationship comprises generating a value pair of the first rock property and the second rock property for each of a plurality of voxels in the first high-resolution image,
wherein the first rock property relationship is generated based at least on the value pair for
each of the plurality of voxels in the first high-resolution image.
4 . The method of claim 1 , further comprising:
identifying a second digital rock portion of the digital rock corresponding to a second rock material segment of the plurality of rock material segments of the rock sample based on the data volume mineralogy and bulk density;
generating, based on a second high-resolution image of a second representative portion of the second rock material segment, a second rock property relationship between the first rock property and the second rock property;
further computing, for each grid cell in the second digital rock portion, the second rock property value of the second rock property based on the second rock property relationship and the first rock property values of the grid cell of the second digital rock portion;
further computing, based on the second rock property relationship and the first rock property values in the second digital rock portion, the second rock property values of the second rock property for assigning to corresponding grid cells in the second digital rock portion; and
further determining, based on the second rock property value for each grid cell in the second digital rock portion, the effective value of the second rock property of the rock sample.
5 . The method of claim 2 , wherein the plurality of rock material segments comprises one or more of a carbonate segment, a sandstone segment, a siltstone segment, and a quartz segment.
6 . The method of claim 1 , wherein the effective value of the second rock property comprises an acoustic velocity value.
7 . A system for modeling a rock sample, comprising:
a computed tomography (CT) scanner configured to:
scan the rock sample to obtain a multi-energy CT-scan image;
an analysis engine comprising at least one processor configured to:
determine a data volume mineralogy and bulk density from the multi-energy CT-scan image,
identify a first rock material segment of the rock sample based on the data volume mineralogy and bulk density, wherein the first rock material segment comprises pores and grains of a single rock material;
identify a first digital rock portion of the digital rock corresponding to the first rock material segment of the rock sample;
generate, using a Focused Ion Beam Scanning Electron Microscope, a first high-resolution image of a first representative portion of the first rock material segment; and
generate, based on the first high-resolution image of a first representative portion of the first rock material segment, a first rock property relationship between a first rock property and a second rock property, wherein the second rock property is associated with a physical rock structure that is resolved in the first high-resolution image and is not resolved at a macro-scale; and
a modeling engine configured to:
select the rock sample, from a well, received by drilling the well using a drilling system;
assign first rock property values of the first rock property to respective grid cells in a digital rock that represents the rock sample, wherein the first rock property values are derived from measurements of the rock sample at the macro-scale;
compute, for each grid cell in the first digital rock portion, a second rock property value of the second rock property based on the first rock property relationship and the first rock property values of the grid cell;
compute, based on the first rock property relationship and the first rock property values in the first digital rock portion, second rock property values of the second rock property for assigning to corresponding grid cells in the first digital rock portion;
determine, based at least on the second rock property values in the first digital rock portion, an effective value of the second rock property of the rock sample; and transmit, to a production system, signals determined from the effective value of the second rock property, and
cause a production valve to produce hydrocarbons based on the effective value of the second rock property of the rock sample.
8 . The system of claim 7 , wherein the first rock material segment forms a contiguous volume of the single rock material.
9 . The system of claim 7 , wherein generating the first rock property relationship comprises generating a value pair of the first rock property and the second rock property for each of a plurality of voxels in the first high-resolution image,
wherein the first rock property relationship is generated based at least on the value pair for each of the plurality of voxels in the first high-resolution image.
10 . The system of claim 7 , the analysis engine further configured to:
identify a second digital rock portion of the digital rock corresponding to a second rock material segment of the rock sample based on the data volume mineralogy and bulk density; and
generate, based on a second high-resolution image of a second representative portion of the second rock material segment, a second rock property relationship between the first rock property and the second rock property, and
the modeling engine further configured to:
further compute, for each grid cell in the second digital rock portion, based on the second rock property relationship and the first rock property values in the second digital rock portion, the second rock property values of the second rock
property based on the second rock property relationship and the first rock property values of the grid cell in the second digital rock portion for assigning to corresponding grid cells in the second digital rock portion; and
further determine, based on the second rock property value for each grid cell in the second digital rock portion, the effective value of the second rock property of the rock sample.
11 . The system of claim 7 , wherein the first rock material segment comprises one or more of a carbonate segment, a sandstone segment, a siltstone segment, and a quartz segment.
12 . The system of claim 7 , wherein the effective value of the second rock property comprises an acoustic velocity value.
13 . A non-transitory computer readable medium (CRM) storing a digital rock for modeling a rock sample including computer-executable data executed by a processor to perform a method comprising the steps of:
drilling a well to obtain sample comprising a plurality of grid cells corresponding to a plurality of locations in the rock sample, the rock sample selected from the drilled well;
assigning first rock property values of a first rock property assigned to respective grid cells in the digital rock, wherein the first rock property values are derived from measurements of the rock sample at a macro-scale;
scanning, via computed tomography (CT) scanner, the rock sample to obtain a multi-energy computer tomography (CT) scan image of the rock sample,
identifying a first rock material segment of the rock sample based on a data volume mineralogy and bulk density determined from the multi-energy CT scan image, wherein the first rock material segment comprises pores and grains of a single rock material;
identifying a first digital rock portion corresponding to the first rock material segment of the rock sample;
generating a first high-resolution image of a first representative portion of the first digital rock segment generated by a Focused Ion Beam Scanning Electron Microscope,
generating a first rock property relationship between the first rock property and a second rock property based on the first high-resolution image of a first representative portion of the first rock material segment, wherein the second rock property is associated with a physical rock structure that is resolved in the first high-resolution image and is not resolved at the macro-scale,
computing, for each grid cell in the first digital rock portion, a second rock property value of the second rock property, based on the first rock property relationship and the first rock property values of the grid cell in the first digital rock portion, for assigning to corresponding grid cells in the first digital rock portion,
computing, for each grid cell in the first digital rock portion, a second rock property value of the second rock property based on the first rock property relationship and the first rock property values of the grid cell;
determining an effective value of the second rock property of the rock sample based at least on the second rock property values in the first digital rock portion, and
producing hydrocarbons, via a production valve, from a production system based on the effective value of the second rock property of the rock sample.
14 . The CRM of claim 13 , wherein the first rock material segment forms a contiguous volume of the single rock material wherein a multi-energy computed tomography scan (CT-scan) image of the rock sample is analyzed to generate a data volume of effective atomic number and bulk density of the rock sample; and wherein a plurality of rock material segments of the rock sample is identified based on the data volume, and wherein the plurality of rock material segments comprise the first rock material segment.
15 . The CRM of claim 13 , wherein generating the first rock property relationship comprises generating a value pair of the first rock property and the second rock property for each of a plurality of voxels in the first high-resolution image,
wherein the first rock property relationship is generated based at least on the value pair for each of the plurality of voxels in the first high-resolution image, and
wherein the effective value of the second rock property comprises an acoustic velocity value.
16 . The CRM of claim 13 , the digital rock further comprising a second digital rock portion of the digital rock corresponding to a second rock material segment of the plurality of rock material segments of the rock sample;
wherein a second rock property relationship between the first rock property and the second rock property is generated based on a second high-resolution image of a second representative portion of the second rock material segment,
wherein, for each grid cell in the second digital rock portion, the second rock property value of the second rock property is further computed, based on the second rock property relationship and the first rock property values of the grid cell in the second digital rock portion, for assigning to corresponding grid cells in the second digital rock portion, and
wherein the effective value of the second rock property of the rock sample is further determined based on the second rock property value for each grid cell in the second digital rock portion.
17 . The CRM of claim 13 , wherein the plurality of rock material segments comprises one or more of a carbonate segment, a sandstone segment, a siltstone segment, and a quartz segment.