Buried Three-Component Receiver S-Wave Attenuation
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Solution Overview
Problem
Current time-lapse 4D seismic monitoring faces challenges in accurately estimating the Q-factor due to variations in near-surface seismic velocity, which affects the repeatability and reliability of reservoir fluid displacement imaging in oil and gas fields.
Innovation Solution
A method and system that utilize buried three-component receivers to separate primary and ghost components from S-waves, allowing for the computation of the Q-factor by measuring time differences and applying a modified log-spectral algorithm, enabling more accurate near-surface corrections and improved seismic data processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional surface receivers are used for 4D seismic monitoring, then the system is simpler to deploy, but the Q-factor estimation accuracy deteriorates due to near-surface velocity variations
Solution Approach 1:
The patent introduces a buried three-component receiver as an intermediary element positioned in the near-surface layer. This receiver acts as a mediator between the seismic waves and the measurement system, enabling direct measurement of S-wave attenuation (Q-factor) in the near-surface conditions. By placing the receiver at an optimal depth within the near-surface layer, the system captures the true near-surface attenuation characteristics without being affected by surface irregularities or deployment complexities.
2Reliability
If near-surface variations are not corrected, then the data acquisition is simpler, but the repeatability of 4D surveys deteriorates
Solution Approach 1:
The patent applies preliminary action by measuring and characterizing the near-surface Q-factor before conducting the main 4D seismic survey. The buried three-component receiver captures the near-surface attenuation properties in advance, allowing these characteristics to be used as correction factors in the subsequent data processing. This preliminary measurement enables the removal of near-surface effects from the 4D data, improving repeatability without requiring complex real-time corrections during acquisition.
Solution Approach 2:
The system establishes a feedback loop where the buried receiver continuously monitors near-surface conditions, and this information feeds back into the data processing workflow. The measured near-surface Q-factor values are used to adjust and correct the main seismic survey data, creating a closed-loop system that automatically compensates for near-surface variations. This feedback mechanism ensures consistent correction across multiple surveys, enhancing repeatability.
3Measurement precision
If conventional processing methods are used, then the processing workflow is simpler, but the separation of primary and ghost components is less accurate
Solution Approach 1:
The patent applies segmentation by separating the seismic wavefield into distinct primary and ghost components using the three-component receiver data. The method segments the complex wavefield into up-going primary waves and down-going ghost waves based on their different propagation directions and polarization characteristics. This segmentation is achieved through mathematical decomposition of the vertical and radial component recordings, allowing precise isolation and analysis of each component type.
Solution Approach 2:
The patent utilizes another dimension by employing three-component receivers that record seismic waves in multiple directions (vertical, radial, and transverse components). This multi-dimensional recording approach provides additional information about wave propagation characteristics, enabling more accurate separation of primary and ghost components through polarization analysis and directional filtering. The extra dimensional data from the third component is crucial for distinguishing between different wave types.
Data Source
AI summary
Computing device and method for determining primary and ghost components from S-waves recorded in near-surface conditions, wherein the S-waves are refracted or reflected from a structure in a subsurface. The method includes a step of receiving seismic data (R, V) with regard to the S-waves, wherein the seismic data includes vertical and radial components recorded with a buried three-component receiver; a step of calculating with a processor a primary component (P) and a ghost component (G) from the vertical and radial components; and a step of computing an image of a subsurface based on the primary and ghost components (P, G). The S-waves form a plane wave.