Rock Physics Guided Migration for Velocity Model Accuracy
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Solution Overview
Problem
Conventional methods for building velocity models prior to seismic migration are inefficient and inaccurate, particularly in complex geologic areas, leading to incorrect subsurface feature depths and inability to derive true earth properties like pore pressure without further processing.
Innovation Solution
A method involving rock physics-guided migration, which generates geologic interpretations, compaction curves, acoustic formation factor curves, and velocity-relationship curves to derive overburden pressure and pore pressure, creating rock physics templates for building accurate depth-dependent velocity models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional migration methods are used, then the process can be completed with standard computational resources, but the computational time required becomes extremely long and the velocity model accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by generating a rock physics template before the migration process. This template, which incorporates geologic interpretation, compaction curves, and acoustic formation factor curves, is prepared in advance to guide the velocity model building. By having this template ready beforehand, the migration process can proceed more efficiently with reduced computational time while maintaining or improving velocity model accuracy, as the template provides a framework that reduces the need for extensive iterative computations.
2Measurement precision
If conventional velocity model building methods are used, then the process is simpler to implement, but the velocity field bears little or no resemblance to true earth velocity and cannot accurately reflect actual geology
Solution Approach 1:
The patent introduces a rock physics template as an intermediary between conventional velocity model building methods and the final velocity field. This template serves as a mediator that incorporates geologic interpretation, compaction curves, and acoustic formation factor curves to guide the velocity model building process. The template acts as a bridge that translates geological knowledge into velocity constraints, thereby improving velocity field accuracy to better reflect true earth velocity and actual geology, while the systematic approach it provides helps manage the increased process complexity.
3Manufacturing precision
If conventional migration processes are used, then standard processing workflows can be maintained, but the migrated image depicts subsurface features at wrong depths and subsurface structures are not clear
Solution Approach 1:
The patent applies preliminary action by creating a rock physics template that incorporates geologic interpretation, compaction curves, and acoustic formation factor curves before the migration process. This template is prepared in advance to provide a framework for accurate velocity model building. By having this template ready beforehand, the migration process can achieve correct depth representation of subsurface features and clear subsurface structures, as the template provides pre-established geological constraints that guide the imaging process.
4Adaptability or versatility
If conventional velocity fields are used, then further conditioning processes are avoided, but the velocity fields cannot be used for deriving true earth properties such as pore pressure
Solution Approach 1:
The patent applies universality by designing the rock physics template to serve multiple functions. The template incorporates geologic interpretation, compaction curves, and acoustic formation factor curves in a unified framework that not only guides velocity model building for accurate imaging but also enables the derivation of true earth properties such as pore pressure. This multi-functional approach increases the utility and adaptability of the velocity field, making it suitable for both imaging and property derivation without requiring separate conditioning processes, thereby managing processing complexity through integration.
Data Source
AI summary
Rock physics guided migration is disclosed to enhance subsurface three-dimensional geologic formation evaluation. In one embodiment, a geologic interpretation is generated based on a seismic data volume. Sets of compaction and acoustic formation factor curves are generated, and these are combined into a set of velocity-relationship curves. A pore pressure is derived and used to establish a pore pressure state. A rock physics template is then generated utilizing the derived information. This rock physics template can be used to refine geologic formation evaluation with any suitable form of migration technique.