Expandable Downhole Tool Radial Sensor Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current downhole tools face challenges in accurately measuring sonic logging in large boreholes due to limited radial separation of sensors, tool eccentering, and inefficient acoustic energy transfer, leading to noise contamination and reduced signal quality.
Innovation Solution
An expandable downhole tool with radially movable arms and a transmitter assembly that can expand to align with the borehole wall, featuring multiple sensors and a transmitter designed to excite various borehole modes, allowing for improved centering and increased radial separation to enhance signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the tool diameter is kept small to maintain maneuverability, then the tool can be easily deployed, but the radial separation between sensors is limited reducing measurement sensitivity
Solution Approach 1:
The tool employs an expandable structure that transitions from a compact configuration during deployment to an expanded configuration during measurement. The arms with sensors can be radially positioned away from the tool body, increasing the effective diameter and radial sensor separation when needed, while maintaining a small diameter for easy deployment when retracted.
2Object-affected harmful factors
If the tool is positioned away from the borehole wall to avoid noise, then tool-borehole contact noise is reduced, but the signal amplitude from the formation decreases
Solution Approach 1:
The solution moves the measurement problem from a two-dimensional plane to three-dimensional space by using arms that can extend radially in multiple directions. This allows sensors to be positioned at optimal distances from both the tool body and borehole wall, capturing signals with sufficient amplitude while maintaining noise avoidance through spatial distribution.
3Device complexity
If the transmitter is positioned centrally in the tool, then the tool structure is simplified, but acoustic energy transfer to the formation is inefficient
Solution Approach 1:
The arms serve as intermediary elements between the centrally positioned transmitter and the formation. The transmitter remains simple and centralized, but the arms transmit and couple acoustic energy to the formation, improving energy transfer efficiency without complicating the transmitter structure itself.
4Measurement precision
If the tool is expanded to increase sensor radial separation, then measurement sensitivity improves, but the device complexity increases
Solution Approach 1:
The tool is divided into modular segments including the tool body, multiple independent arms, and an open/close mechanism. This segmentation allows the complex expandable function to be achieved through simpler, independent components that can be manufactured and assembled separately, reducing overall system complexity.
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 expandable tool design improves sonic sensitivity, maintains tool alignment, and enhances data accuracy by increasing the radial separation of sensors and improving transmitter-to-formation coupling, thereby improving the measurement of monopole, dipole, and quadrupole modes.
Implementation Method 1
The at least one transmitter is configured to excite the borehole rock, and the at least one sensor is configured to measure the signal that propagates through the rock due to the excitation from the transmitter
Implementation Method 2
a dipole source transmits at a specific frequency, depends on borehole size and formation velocity, in sonic logging typically within 0.3 to 5 kilohertz
Data Source
AI summary
A downhole tool, having a central axis defined, may selectively include a sensor section including one or more arms connected to the tool body with an open/close mechanism. The open/close mechanism is configured to move in a radial direction with respect to the axis of the tool body. The tool also includes at least one sensor attached to the arm, and the tool may include at least one transmitter section on the tool. The transmitter is configured to transmit acoustic energy to a formation.