Downhole Centralizer Arms for Constant-Force Tool Centering
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Solution Overview
Problem
Downhole acoustic tools used for cement bond logging and radial bond logging are sensitive to the position within the casing, leading to inaccurate interpretation of cement bonding quality due to eccentering from the central axis, which is not effectively addressed by existing centralizers.
Innovation Solution
A downhole tool with a centralizer mechanism comprising pivotably connected arms that can move against the sidewall of the wellbore to centralize the tool string, maintaining a constant force despite changes in the inner diameter, using hydraulic actuators and sensors to control the positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional centralizer is used to position the downhole tool, then the tool may be centered, but the centralizer cannot maintain constant force when the wellbore diameter changes, leading to eccentering and inaccurate measurements
Solution Approach 1:
The centralizer employs dynamically adjustable arms with variable geometry that can change their configuration in response to wellbore diameter variations. The arms are equipped with actuators that adjust the arm geometry to maintain optimal contact force and positioning across different wellbore sizes, enabling the centralizer to adapt rather than remain static
Solution Approach 2:
The centralizer changes physical parameters including arm length, arm angle, and contact force magnitude in response to wellbore diameter changes. Sensors detect diameter variations and trigger adjustments to these parameters, ensuring the tool maintains centralized position and appropriate contact force regardless of the wellbore size
2Ease of operation
If the downhole tool is eccentered in the wellbore, then the tool can be deployed, but the casing arrival amplitudes are perturbed, resulting in inaccurate cement bonding interpretation
Solution Approach 1:
The centralizer incorporates sensors that continuously monitor the tool's position within the wellbore and the contact force applied by the arms. This feedback information is used to adjust arm positioning and geometry in real-time, ensuring the tool remains centered and measurements are accurate throughout deployment and operation
3Adaptability or versatility
If the wellbore inner diameter varies along the wellbore, then the tool must adapt to different diameters, but conventional centralizers cannot maintain constant force, causing positioning instability
Solution Approach 1:
The centralizer employs dynamically adjustable arms with variable geometry that can change their configuration in response to wellbore diameter variations. The arms are equipped with actuators that adjust the arm geometry to maintain optimal contact force and positioning across different wellbore sizes, enabling the centralizer to adapt rather than remain static
Solution Approach 2:
The centralizer incorporates sensors that continuously monitor the tool's position within the wellbore and the contact force applied by the arms. This feedback information is used to adjust arm positioning and geometry in real-time, ensuring the tool remains centered and measurements are accurate throughout deployment and operation
Data Source
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AI summary
A downhole centralizer operable to be coupled with a tool string and conveyed within a downhole passage, wherein the downhole passage is a wellbore or a tubular member disposed in the wellbore. The downhole centralizer may have a plurality of arms that are operable to move against a sidewall of the downhole passage to centralize at least a portion of the tool string within the downhole passage, impart an intended force against the sidewall of the downhole passage, and maintain the intended force substantially constant while the tool string is conveyed along the downhole passage and an inner diameter of the downhole passage changes.