Dual Packer Pressuremeter Testing for Shear Modulus Estimation
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Solution Overview
Problem
Existing methods for determining the in situ static shear modulus (G) using a dual packer tool are limited, as they often require modifying the tool or using a single packer configuration, which may not be feasible in all scenarios, and there is a need for new methods to accurately estimate this parameter in geological formations.
Innovation Solution
A method and system using a wireline formation tester (WFT) tool with multiple packers to perform pressuremeter testing (PMT) by actuating the packers in different formations, measuring pressure and fluid volume, and analyzing these measurements to estimate the shear modulus (G) of the geological formation, accounting for tool and casing stiffness using equations 1-12.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single packer configuration is used for pressuremeter testing, then the measurement precision of formation elastic moduli is improved, but the device complexity increases and tool modification is required
Solution Approach 1:
The patent uses the second packer as an intermediary reference element to measure and account for tool stiffness. By inflating the second packer against the borehole wall and measuring its pressure-volume response, the tool stiffness is characterized and then subtracted from the first packer measurements to obtain accurate formation elastic moduli without requiring tool modification or single-packer configuration
Solution Approach 2:
The dual packer tool is designed to perform multiple functions: the first packer performs pressuremeter testing for formation elastic moduli measurement, while the second packer simultaneously serves as both a functional testing element and a reference for tool stiffness characterization. This multi-functionality eliminates the need for separate tool modifications or dedicated single-packer tools
2Ease of operation
If a dual packer tool is used without modification, then the ease of operation is improved, but the measurement precision of formation elastic moduli deteriorates due to tool stiffness interference
Solution Approach 1:
The patent implements a feedback mechanism where the pressure-volume measurements from the second packer are used to determine tool stiffness, which then feeds back into the calculation process for the first packer measurements. This feedback loop allows the system to automatically compensate for tool stiffness interference, maintaining measurement precision while using the convenient dual packer configuration
Solution Approach 2:
The patent extracts and separates the tool stiffness component from the total measured response. By independently characterizing the tool stiffness using the second packer and then removing this component from the first packer measurements, the method isolates the pure formation response, achieving accurate elastic moduli determination without modifying the dual packer tool
3Measurement precision
If one packer is removed or isolated in a dual packer module, then the measurement precision is improved, but the device complexity increases and the ease of operation deteriorates
Solution Approach 1:
The patent merges the functionality of both packers into a unified measurement system. Instead of removing or isolating one packer, both packers are inflated and measured simultaneously, with the second packer's data serving to correct the first packer's measurements. This combining approach maintains the simplicity of operating a dual packer tool while achieving single-packer level measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate determination of the shear modulus (G) of geological formations by accounting for tool and casing stiffness, allowing for precise estimation of formation properties without requiring tool modifications, thereby enhancing the accuracy of geomechanical assessments.
Implementation Method 1
The PMT consists of inflating and deflating a single packer downhole while measuring the pressure exerted on the borehole wall and the volume of fluid injected into the packer
Implementation Method 2
G governs the elastic behavior of materials in general, and geomaterials, in particular. Estimation of the fraction of the injected fluid volume that contributes to expansion of the borehole wall, rather than deforming components of the PMT tool
Data Source
AI summary
A method including deploying a formation testing tool in a borehole, actuating first and second packers of the formation testing tool in the borehole, obtaining measurements in response to actuation of the first and second packers of the formation testing tool in the borehole, and analyzing the measurements to estimate at least a shear modulus (G) of a geological formation surrounding the borehole.