Geomechanical Modeling via Time-Lapse Displacement Boundary Conditions

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Solution Overview

Problem

Current geomechanical modeling methods fail to accurately update rock displacement and strain models using time-lapse seismic data, particularly due to the lack of effective methods for deriving displacement increments from time-lapse seismic displacements, which hinders the refinement of geomechanical models and interpretation of time-lapse data.

Innovation Solution

A new workflow is introduced that uses displacement boundary conditions derived from time-lapse travel time shifts and time strain to update geomechanical model parameters, allowing for the extraction of displacements at the model boundaries, calculation of stress and strain increments, and comparison with time-lapse observations to refine material properties, faults, and the rock strain-velocity change relationship (R factor).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If time-lapse seismic data is used to update geomechanical models, then measurement precision of rock displacement and strain is improved, but device complexity of the modeling workflow increases

Engineering Contradiction:

Improverock displacement and strainVSAvoidmodeling workflow

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The geomechanical modeling workflow is segmented into distinct modules: time-lapse seismic data processing, displacement boundary condition derivation, geomechanical simulation, and model updating. This segmentation allows each module to be independently optimized and managed, reducing overall workflow complexity while maintaining high measurement precision for rock displacement and strain.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Displacement boundary conditions serve as an intermediary between time-lapse seismic data and geomechanical model parameters. By deriving these boundary conditions from seismic observations and applying them to the geomechanical simulator, the system bridges the gap between seismic data and mechanical properties, enabling accurate model updating without direct complex coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If displacement boundary conditions are derived from time-lapse seismic data, then reliability of geomechanical model updates is improved, but difficulty of detecting and measuring increases

Engineering Contradiction:

Improvegeomechanical model updatesVSAvoiddisplacement increments

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

Displacement boundary conditions are derived from time-lapse seismic data before being applied to the geomechanical simulator. This preliminary derivation process converts seismic measurements into meaningful displacement increments that can be directly used to update model parameters, ensuring reliability while managing measurement difficulty through pre-processing.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces direct mechanical measurement of displacement increments with seismic wave-based indirect measurement. By using time-lapse seismic data to infer displacement boundary conditions, the system avoids the complexity of direct mechanical measurement while maintaining reliable geomechanical model updates through the relationship between seismic velocity changes and rock property changes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If geomechanical model is decoupled from reservoir model, then ease of operation is improved, but loss of information may increase

Engineering Contradiction:

Improvehistory matchingVSAvoidcoupling effects

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The geomechanical model is extracted and decoupled from the reservoir model, allowing independent history matching and optimization. By separating the geomechanical simulation from the reservoir simulation, the workflow becomes more manageable and easier to operate, while the essential coupling effects are preserved through the use of displacement boundary conditions that transfer information between the two models.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS10545261B2Geomechanical modeling using dynamic boundary conditions from time-lapse data

Publication Date: 2020.01.28 WESTERNGECO LLC

AI summary

A method for modelling geomechanical effects in the subsurface by conditioning geomechanical model parameters to time-lapse observations. The model is driven by displacement boundary conditions derived from observed time-lapse travel time shift and time strain. The displacements at the boundaries of the model are extracted from time-lapse data, converted from travel time shift to depth shift and lateral shifts if necessary, and applied as displacement increments on the initial geomechanical model. Subsequently, increments of stresses and strains are calculated by the geomechanical simulator, and time-lapse related parameters in the interior of the model are compared with the time-lapse observations. This enables a comprehensive study of mismatch between simulations and observations that can be used to update material properties, faults, fractures and the rock strain-velocity change relationship (R factor). The updated material properties may be used to make understand subsurface conditions including identifying drilling hazards, well integrity or reservoir integrity.