Seismic Attribute Alignment for Joint PP/PS Inversion
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Solution Overview
Problem
Current seismic prospecting techniques face challenges in accurately aligning compressional wave (PP) and converted shear wave (PS) reflection data due to differences in phase and amplitude, leading to time alignment errors in joint PP/PS inversion and geologic interpretation.
Innovation Solution
The method involves transforming PP and PS mode data into enhanced representations by calculating phase-consistent seismic attributes, performing a first pass alignment based on selected horizons or Vp/Vs ratios, and applying a refined alignment using time-transfer functions to achieve accurate registration and inversion of subsurface data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment methods are used for PP and PS data, then the alignment process is simple, but time alignment errors occur due to phase and amplitude differences
Solution Approach 1:
The patent introduces seismic attributes (AVA attributes, impedance, velocity) as intermediary elements that serve as phase-consistent references for aligning PP and PS data. These attributes act as mediators that bridge the phase and amplitude differences between the two data types, enabling accurate alignment without direct complex correlation between the original seismic traces.
Solution Approach 2:
The patent performs preliminary calculations of seismic attributes (AVA intercepts, gradients, impedance) from the PP and PS data before the actual alignment process. These pre-computed attributes provide phase-consistent reference information that simplifies the subsequent alignment step, allowing the alignment to be based on physically meaningful parameters rather than raw seismic traces.
2Measurement precision
If seismic attributes are calculated and refined alignment is performed, then alignment accuracy and seismic resolution are retained, but computational complexity increases
Solution Approach 1:
The patent transforms the alignment problem from the time-domain seismic traces to the attribute domain (AVA intercepts, gradients, impedance). By changing the parameters used for alignment from raw seismic amplitudes to derived seismic attributes, the method achieves phase-consistent alignment that preserves seismic resolution while the computational overhead is managed through efficient attribute calculation and time-transfer function application.
Data Source
AI summary
Method for aligning converted wave seismic reflection data (PS data) with conventional PP seismic reflection data so that both data types may be used to more accurately image the subsurface for hydrocarbon exploration or field development. Amplitude vs. angle (AVA) or amplitude vs. offset (AVO) attributes of PP and PS seismic data are identified and defined, which attributes are theoretically expected to be in phase and optimize seismic resolution in the data. In one embodiment of the invention, such attributes are calculated (310), then the same horizons are identified in a series of PP attributes and in a series of PS attributes, then the second series is aligned with the first at the horizon locations (316, 320), then a time transfer function is generated and applied to the PS mode data (322), and the aligned joint-mode data are inverted (326) using, for example, AVA attributes.