3D Fracture Abundance Evaluation Using Geometric Primitives
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Solution Overview
Problem
Conventional methods for evaluating fracture abundance in subsurface formations, particularly the P 32 value, face challenges due to difficulties in accurately obtaining fracture sizes from borehole data, leading to relative measurements with large uncertainties in 3D grids.
Innovation Solution
A three-dimensional approach using geometric primitives such as triangular elements within a three-dimensional volume to define a fracture network, allowing for direct calculation of fracture abundance parameters like P 32 fracture density by summing areas of primitives within cells and normalizing by cell volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional borehole imaging and core logging methods are used to obtain fracture sizes, then the measurement process is simple, but the accuracy of fracture size measurement is poor leading to large uncertainties in P32 values
Solution Approach 1:
The patent introduces a three-dimensional seismic inversion process as an intermediary method to bridge borehole data and formation-scale fracture characteristics. By using seismic data as a mediator, the system can infer fracture abundance parameters (P10, P32, P43 values) throughout the formation volume without requiring direct measurement of every fracture, thus improving accuracy while reducing the difficulty of complete fracture characterization.
Solution Approach 2:
The patent replaces direct mechanical measurement methods (borehole imaging, core logging) with a computational inversion approach. Instead of physically measuring fractures in the borehole and attempting to extrapolate, the system uses seismic wave propagation characteristics and inversion algorithms to directly model fracture abundance in three-dimensional space, substituting mechanical measurement with computational modeling.
2Measurement precision
If statistical interpolation methods are used to infer P32 values in a three-dimensional grid, then the computation is straightforward, but the uncertainties in the interpolated values are large
Solution Approach 1:
The patent implements an iterative inversion process where the calculated fracture abundance parameters are continuously compared with borehole measurement data, and the inversion model is adjusted accordingly. This feedback mechanism allows the system to refine the P32 values in each iteration, reducing uncertainties by ensuring the model remains consistent with actual borehole observations while providing reliable three-dimensional interpolation.
Solution Approach 2:
The patent changes the approach from using fixed statistical interpolation parameters to using inversion-based parameters that are dynamically adjusted based on the specific formation characteristics and borehole data. By inverting the relationship between seismic data and fracture abundance, the system can adapt the P32 values to local formation conditions, improving both accuracy and reliability of the interpolated values.
3Ease of manufacture
If relative P32 measurements are calculated from borehole data, then the measurement process is simple, but the values cannot be directly used for accurate reservoir modeling
Solution Approach 1:
The patent transitions from one-dimensional borehole measurements to three-dimensional inversion results. By using seismic data that captures formation characteristics in multiple dimensions (horizontal and vertical extents), the system can calculate absolute P32 values throughout the formation volume rather than just along the borehole trajectory. This dimensional expansion allows the values to be directly applicable to reservoir modeling while maintaining computational feasibility.
Data Source
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AI summary
A method, apparatus, and program product evaluate fracture abundance in a subsurface formation by modeling a fracture network in a three-dimensional volume using geometric primitives. A fracture abundance parameter, e.g., a P32 fracture density, may be determined in part based upon the combined areas of the primitives with cells of a three-dimensional grid.