Downhole Impact Logging for Depth-Specific Wellbore Elasticity
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Solution Overview
Problem
Existing methods for assessing downhole elasticity in wellbores lack precision and depth specificity, as surface measurements are influenced by the entire wellbore and surrounding formations, while core samples only provide discrete data points, failing to capture the full complexity of subsurface rock properties, especially in heterogeneous formations.
Innovation Solution
A logging tool with extendable arms and impact hammers that deliver impulse loads to the wellbore wall, coupled with accelerometers to measure the resulting acceleration, allowing for direct, continuous measurement of elasticity along the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface measurements are used to assess downhole elasticity, then valuable data can be collected, but precision and depth specificity are lost due to influence from the entire wellbore and surrounding formations
Solution Approach 1:
The measurement system is segmented into multiple discrete measurement points along the wellbore using a array of accelerometers distributed at different depths and radial positions. This segmentation allows isolation of local elastic properties at specific depth intervals, eliminating the averaging effect that plagues surface measurements and enabling depth-specific elasticity assessment.
Solution Approach 2:
The approach transitions from surface-based two-dimensional measurements to three-dimensional downhole measurements by deploying accelerometers at multiple radial distances and depths. This dimensional expansion enables resolution of spatial variations in elastic properties that are completely lost in surface measurements, providing both precision and depth specificity simultaneously.
2Measurement precision
If core samples are collected to assess downhole elasticity, then detailed geological information is obtained, but only discrete data points are provided that fail to capture full complexity of subsurface rock properties
Solution Approach 1:
The logging tool provides continuous measurement along the wellbore by maintaining constant contact between the accelerometer array and the wellbore wall throughout the entire downhole section. This continuous action eliminates the discrete, point-specific nature of core samples, delivering uninterrupted elastic property data that captures the full complexity of subsurface rock properties along the entire wellbore length.
Solution Approach 2:
The system uses the wellbore wall itself as the test object, eliminating the need for separate core samples. The accelerometers directly measure elastic properties of the formation rock in situ, making the formation itself the source of the measurement data rather than requiring extraction and laboratory analysis of discrete samples.
3Productivity
If direct downhole measurements are made to provide real-time continuous data, then comprehensive understanding of mechanical environment is achieved, but measurement complexity increases
Solution Approach 1:
The accelerometer array serves multiple functions simultaneously: it measures elastic properties, monitors wellbore stability, and provides continuous depth-specific data. This multi-functionality reduces the need for separate specialized tools, thereby managing overall system complexity while achieving comprehensive continuous measurement capabilities.
Solution Approach 2:
The system replaces complex mechanical core sampling and laboratory testing procedures with a simplified electronic measurement system using accelerometers. This substitution of mechanical field-based measurement with electronic sensing reduces operational complexity while enabling real-time continuous data collection throughout the wellbore.
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
Provides real-time, continuous data on wellbore elasticity, reducing inaccuracies by measuring the formation's authentic behavior under natural conditions, enabling site-specific engineering applications such as wellbore stability analysis and structural foundation design.
Implementation Method 1
In a geo-mechanical context, elasticity refers to the ability of rocks or other geological formations to deform in response to an applied stress and subsequently revert to their original state when the stress is relieved.
Implementation Method 2
one or more accelerometers operably coupled to each hammer and operable to detect an acceleration of the hammer induced by delivering the impulse load
Data Source
AI summary
A wellbore logging tool may include a support body and a plurality of arms selectively movable from a retracted position to an extended position with respect to the support body. A hammer is supported at a radially outermost end of each of the arms that is selectively operable to deliver an impulse load to a wall of the wellbore. One or more accelerometers are operably coupled to each hammer to detect an acceleration of the hammer induced by delivering the impulse load. A Hertzian model may be employed to determine characteristics of the wellbore wall from the acceleration of the hammers.