Variable Radial Stress Wellbore Pressure Testing
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Solution Overview
Problem
Conventional pressure testing systems for subterranean rock formations fail to accurately restore the initial stress state around a wellbore after drilling, leading to premature failure and compromised data integrity due to the application of constant radial stress loads that exceed post-drilling tangential stresses.
Innovation Solution
A pressure testing system that applies a radially varying pressure load around the circumference of the wellbore using adjustable, inflatable members controlled by a module to match the initial stress state, thereby restoring the initial stress distribution and allowing for accurate geomechanical property determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a constant radial stress load is applied to restore the initial stress state, then the stress restoration is simplified, but the rock formation fails prematurely due to exceeding post-drilling tangential stress
Solution Approach 1:
The patent divides the loading device into multiple independently controllable loading units distributed around the wellbore circumference. Each unit can apply a different radial stress load tailored to the local post-drilling stress conditions at its angular position, allowing the system to restore initial stress state without exceeding local tangential stress limits and causing premature failure.
Solution Approach 2:
The patent employs an adjustable and controllable loading mechanism where the radial stress load can be dynamically modified during the testing process. The loading magnitude and distribution can be adjusted in real-time based on measured rock formation response and known stress fields, enabling precise restoration of initial stress state while preventing premature failure.
2Device complexity
If a constant radial stress load is applied to simplify the testing process, then the device complexity is reduced, but the measurement precision is compromised due to premature rock formation failure
Solution Approach 1:
The loading device is segmented into multiple independently controllable loading units distributed around the wellbore. Each unit can be controlled separately to apply the appropriate radial stress load for its local position, enabling precise restoration of initial stress state without premature failure, thereby ensuring accurate geomechanical property measurements.
Solution Approach 2:
The patent changes the parameter of radial stress load from a constant value to a variable value that depends on angular position around the wellbore. This parameter change allows the system to match the variable post-drilling stress distribution and restore the initial stress state accurately, preventing premature failure and ensuring measurement precision.
3Ease of operation
If a constant radial stress load is applied to ease operation, then the ease of operation is improved, but the adaptability to varying stress conditions around the wellbore is reduced
Solution Approach 1:
The system applies different radial stress loads at different angular positions around the wellbore, matching the local post-drilling stress conditions. This local customization of loading allows the system to adapt to the varying stress state around the wellbore while maintaining ease of operation through automated control.
Solution Approach 2:
The loading device incorporates dynamic adjustment capability that allows the radial stress load to be modified during operation. This dynamic adaptability enables the system to respond to varying stress conditions around the wellbore and accurately restore the initial stress state at each angular position.
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
The system effectively reestablishes the initial stress state, preventing premature rock formation failure and enabling the acquisition of accurate geomechanical properties reflective of the pre-drilling state, thus maintaining data integrity and providing reliable measurements.
Implementation Method 1
The multiple expandable members include multiple inflatable members that are configured to inflate upon receiving hydraulic fluid and configured to deflate upon being emptied of hydraulic fluid
Data Source
AI summary
A pressure testing system for analyzing a rock formation includes a tubular support member sized to pass into a wellbore of the rock formation and an adjustable loading device configured to exert a radial load against the wall of the wellbore. The adjustable loading device includes multiple expandable members distributed around a circumference of the tubular support member and configured to expand to respectively exert multiple radial pressures against the wall of the wellbore that together provide the radial load. The pressure testing system further includes a control module configured to selectively control expansion of each expandable member of the multiple expandable members to vary the radial load exerted by the adjustable loading device as a function of an angle around the circumference of the tubular support member.