Borehole Image Gap Filling Using Trend Reconstruction
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Solution Overview
Problem
Borehole image logs often have coverage gaps due to electrode pads not fully covering the borehole wall, limiting the completeness of the electrical and acoustic maps of subterranean formations, which hampers accurate geological and reservoir evaluation.
Innovation Solution
A method and apparatus that reconstruct missing structure and simulate missing texture in borehole images using trend extraction and stochastic texture reconstruction, enabling the creation of fullbore images with 360-degree coverage by filling gaps with patterns similar to adjacent regions, based on data from downhole tools and surface equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrode pads are arranged in fixed patterns on imaging tools, then the tool structure is simplified and easier to manufacture, but coverage gaps occur between pads resulting in incomplete borehole wall imaging
Solution Approach 1:
The patent creates virtual copies of borehole image data by reconstructing missing portions through extrapolation algorithms. The system copies structural patterns and textural features from visible regions to fill gaps, generating synthetic image data that complements the actual measurements without requiring additional physical pads.
Solution Approach 2:
The patent introduces computational algorithms as an intermediary between the physical pads and the final borehole image. These algorithms process the partial measurements from pads, extrapolate missing information, and synthesize a complete fullbore image, acting as a mediator that transforms incomplete data into comprehensive geological information.
2Device complexity
If fewer electrode pads are used to reduce tool complexity, then device complexity decreases, but borehole image coverage and completeness deteriorate
Solution Approach 1:
The system reconstructs missing borehole wall information by copying structural patterns and textural characteristics from adjacent measured regions. This virtual replication allows the system to achieve complete 360-degree coverage reliability while using fewer physical pads, as the missing data is synthesized rather than physically measured.
Solution Approach 2:
The patent performs preliminary extrapolation of structural trends and textural patterns from measured regions before final image assembly. By pre-computing the likely appearance of missing portions based on geological continuity principles, the system ensures reliable complete coverage without requiring additional pads during the imaging process.
3Loss of information
If multiple imaging runs are performed to achieve complete coverage, then borehole wall coverage improves, but measurement time and operational complexity increase
Solution Approach 1:
The system performs preliminary extrapolation and gap-filling computations during a single imaging run, rather than requiring multiple sequential runs. By computing virtual pad measurements in advance based on geological continuity from visible regions, the system achieves complete coverage from one pass, significantly reducing total imaging time.
Solution Approach 2:
The patent creates complete borehole coverage by copying and extrapolating geological patterns from measured to unmeasured regions within a single imaging run. This virtual replication of borehole wall information eliminates the need for multiple physical imaging passes, reducing operational time while maintaining complete coverage.
4Productivity
If gap filling is performed using simple interpolation, then processing speed increases, but reconstruction accuracy and geological fidelity decrease
Solution Approach 1:
The patent applies different processing approaches to different regions of the borehole image based on local geological characteristics. Structural extrapolation methods are applied to maintain geological continuity in formation boundaries and layering, while textural synthesis methods are applied to preserve local rock fabric patterns. This localized quality adjustment ensures high reconstruction accuracy while maintaining computational efficiency.
Solution Approach 2:
The system dynamically adjusts extrapolation parameters such as search window size, weighting factors, and pattern matching thresholds based on the specific geological context of each region. By changing these parameters locally rather than using fixed global settings, the system achieves high reconstruction accuracy across diverse geological formations while maintaining reasonable processing speeds.
Data Source
AI summary
The present disclosure introduces methods and apparatus for acquiring a borehole image corresponding to a sidewall surface of a borehole that penetrates a subterranean formation, wherein the subterranean formation comprises structural elements and a varying geophysical characteristic. The borehole image comprises structure corresponding to the structural elements, texture corresponding to the varying geophysical characteristic, and coverage gaps (605) in which the structure and texture are missing. Trends corresponding to the structure are extracted from the borehole image. Missing structure within the gaps (605) is reconstructed based on the extracted trends. Missing texture within the gaps is simulated based on the borehole image and the reconstructed structure. A fullbore image is constructed based on the borehole image, the reconstructed structure within the gaps, and the simulated texture within the gaps.