Envelope-Guided Low Frequency Model for Seismic Inversion
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Solution Overview
Problem
Conventional methods for building low frequency models in seismic inversion are inadequate, particularly in sparse well locations, leading to inaccuracies such as the 'bulls-eye effect and failure to capture lithology variations essential for reservoir characterization.
Innovation Solution
An envelope-guided low frequency model building technique that uses envelope data to interpolate a least-squares optimized coefficient model onto a uniform 3D seismic survey space, incorporating covariance techniques to generate a three-dimensional low frequency model that conforms to subsurface structures and captures amplitude and phase information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional inverse distance weighting interpolation is used to build low frequency model, then the interpolation process is simple, but the model introduces bulls-eye effect and degrades accuracy
Solution Approach 1:
The patent introduces envelope data as an intermediary guide to constrain the interpolation process. The envelope data represents the amplitude envelope of seismic reflections and serves as a mediator between the sparse well log data and the target 3D spatial grid, enabling the interpolation to respect subsurface structural boundaries while avoiding the bulls-eye effect of conventional methods
Solution Approach 2:
The patent applies different interpolation strategies in different spatial regions based on the envelope data characteristics. Areas with strong envelope signals (indicating coherent reflections) receive different treatment compared to areas with weak envelope signals, allowing the model to adapt to local subsurface structures and maintain accuracy without imposing a single interpolation method throughout
2Manufacturing precision
If Kriging method with horizon picking is used, then the model conforms to subsurface structures, but the process becomes tedious and time consuming
Solution Approach 1:
The patent performs preliminary processing of seismic data to extract envelope data before the interpolation process. This envelope data is pre-computed and stored as a guide framework, eliminating the need for time-consuming interactive horizon picking during the modeling process while still achieving structural conformity
Solution Approach 2:
The envelope data automatically guides the interpolation process without requiring manual intervention. The system uses the pre-extracted envelope information to self-regulate the interpolation weights and constraints, achieving structural conformity autonomously without human expertise in horizon picking
3Measurement precision
If blended neighbor method with tensor field is used, then the interpolation uses seismic image guidance, but the model cannot capture lithology variation embedded in seismic amplitude and phase
Solution Approach 1:
The patent transforms the seismic data into envelope data that preserves amplitude information, and combines this with phase information from the original seismic data. This parameter transformation enables the interpolation to capture lithology variations that are embedded in both amplitude and phase, going beyond what conventional tensor field methods can achieve
Data Source
AI summary
A method and system for generating and displaying a low frequency model for a seismic survey region are provided. The method and system may include defining a seismic survey geometry of the seismic survey region; processing seismic data to generate a stacked seismic data and well log data to obtain elastic attributes; importing stacked seismic data and processed well log data into the defined seismic survey geometry; generating envelope data using the stacked seismic data; generating a low frequency trace for each well; calculating a least-squares optimized coefficient model at each well location based upon the generated envelope data and the low frequency trace for each well; interpolating the coefficient model to the seismic survey geometry using a covariance technique and the imported stacked seismic data; and generating a three-dimensional low frequency model by inversion using the envelope data and the interpolated coefficient model for display.