Time-lapse seismic difference image generation
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Solution Overview
Problem
Traditional time-lapse seismic surveys face challenges in maximizing data capture and minimizing costs, as they often require repetitive source and sensor placement to compute difference images, which can be affected by cable length variations and migration issues.
Innovation Solution
The method involves sorting seismic data from both surveys into common mid-point (CMP) gathers, estimating and calculating trace differences between surveys at each CMP offset coordinate, and processing these differences to generate a time-lapse difference image, allowing for shifted source and sensor arrangements while increasing the trace fold and improving data quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If source and sensor placement is repeated as closely as possible to compute difference image, then measurement precision is improved, but adaptability deteriorates
Solution Approach 1:
The patent changes the spatial parameters of the survey configuration by allowing offset shifts between baseline and monitor surveys. Instead of requiring identical source-receiver offsets, the method accommodates different offset values while maintaining difference image quality through appropriate processing techniques that handle the parameter variations.
2Productivity
If new seismic data is captured to maximize usefulness, then productivity is improved, but manufacturing precision deteriorates
Solution Approach 1:
The patent allows changes in survey parameters including offset distances and azimuth angles between baseline and monitor surveys. This enables new data to be captured with different geometric configurations while still producing valid difference images through processing methods that account for these parameter changes.
Solution Approach 2:
The method transitions from static, fixed survey configurations to dynamic configurations where offset shifts and azimuth changes are permitted. This dynamic approach allows the survey design to adapt to operational constraints while maintaining data quality for time-lapse analysis.
3Manufacturing precision
If offset shifts are implemented to increase trace fold, then manufacturing precision is improved, but measurement precision deteriorates
Solution Approach 1:
The patent systematically changes the offset parameters between surveys to achieve increased trace fold. By allowing offset shifts, the method accumulates more traces at common midpoints, improving the stacking quality and signal-to-noise ratio while maintaining difference image accuracy through appropriate processing.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Methods for generating a time lapse difference image. In one implementation, the method includes estimating a trace in a first seismic survey data set at each trace coordinate of a second seismic survey data set (430), estimating a trace in the second seismic survey data set at each trace coordinate of the first seismic survey data set (435) and calculating trace differences between the first seismic survey data set and the second seismic survey data set at each trace coordinate of the first seismic survey data set and the second seismic survey data set (440).