3D Image Model for Source Rock Permeability Evaluation
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Solution Overview
Problem
Current methods for evaluating subsurface rock permeability, particularly in heterogeneous formations like shales and mudrocks, face challenges due to limited porosity and connectivity, as well as the difficulty in accurately scaling up nanoscale data to larger scales, leading to inadequate representation of petrophysical properties.
Innovation Solution
Generating a 3D image model of the source rock using extensive pore databases and erosion/dilation methods to mimic real pore systems, allowing for the characterization and simulation of permeability, conductivity, and mechanical properties without requiring prior knowledge of parameters like capillary pressure or permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 2D SEM imaging is used to study rock structures, then high resolution can be achieved, but the field-of-view is limited and cannot capture large-scale heterogeneity
Solution Approach 1:
The patent transitions from 2D SEM imaging to 3D FIB-SEM imaging, adding the third dimension (depth) to capture both high-resolution pore structures and large-scale heterogeneity. The 3D imaging technique allows visualization of pore connectivity and spatial distribution throughout the rock volume, resolving the contradiction between resolution and field-of-view by enabling simultaneous observation of micro-scale pore details and macro-scale rock fabric.
2Area of stationary object
If 3D FIB-SEM imaging is used to capture large FOV, then more comprehensive pore distribution can be observed, but the porosity and connected porosity measurements vary considerably
Solution Approach 1:
The patent segments the 3D rock volume into multiple slices or sub-volumes for systematic analysis. By dividing the large FOV into manageable segments, the method maintains measurement consistency within each segment while capturing overall heterogeneity across the entire volume. This segmentation approach allows for standardized porosity and connectivity measurements that can be aggregated to represent the bulk rock properties.
Solution Approach 2:
The patent employs parameter changes in the imaging process, including adjusting the ion beam current, voltage, and scanning parameters to optimize the balance between field-of-view and measurement consistency. By carefully controlling imaging parameters, the method reduces variability in porosity measurements while maintaining comprehensive coverage of the rock structure.
3Measurement precision
If nanoscale laboratory data is used to evaluate permeability, then detailed pore structure information is available, but it is inadequate for scaling up to larger scales
Solution Approach 1:
The patent creates digital 3D copies or models of the rock pore structure from FIB-SEM imaging data. These digital replicas preserve nanoscale pore structure details while enabling virtual experiments and simulations at various scales. The digital models can be used to calculate permeability and other transport properties without requiring physical scaling, thus resolving the contradiction between detailed measurement and scale applicability.
Data Source
AI summary
A method for evaluating a rock permeability is disclosed. The method includes generating a binary 2D field of view image; selecting a plurality of regions from the generated image; locating a plurality of pores from the plurality of image seeds; collecting pore data for each pore of the plurality of pores; characterizing the pore data for each pore of the plurality of pores; storing pore data for each pore from the plurality of pores; choosing an image seed of the plurality of image seeds as an initial slice of the 3D image model of the source rock; modulating the pore data for each pore of the plurality of pores relative to the plurality of pores from each image seed of the plurality of image seeds; generating and combining the plurality of new images into a 3D volume to generate the 3D image model of the source rock.