Borehole Imaging Tool with Moveable Flat Mirror
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Solution Overview
Problem
Existing methods for obtaining optical images of borehole walls face issues such as image distortion and complexity due to the use of hemispherical or conical mirrors, and the limited space in boreholes makes it difficult to mount and rotate cameras effectively, while also being hindered by opaque well fluids.
Innovation Solution
A tool with a moveable flat mirror and light source, housed in a transparent sleeve, allows for axial movement, rotation, and angle adjustment to minimize distortion, and includes a pump system to isolate and fill the borehole interval with a clear fluid for imaging, along with fluid jets to clean the wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If hemispherical or conical mirrors are used to image the borehole wall, then radial coverage is improved, but image distortion increases and device complexity increases
Solution Approach 1:
The imaging function is segmented between a flat mirror and a linear array detector. The flat mirror provides undistorted reflection while the linear array detector captures sequential portions of the borehole wall as the mirror moves, eliminating the need for curved mirrors that cause distortion.
Solution Approach 2:
The flat mirror is made movable along the borehole wall to dynamically scan different sections. This dynamic positioning allows a simple flat mirror to achieve comprehensive coverage that would otherwise require complex curved mirror arrangements.
2Area of stationary object
If a camera is mounted radially and rotated around the tool axis to provide full coverage, then radial coverage is improved, but device complexity increases
Solution Approach 1:
The mechanical rotation of the camera is replaced with a simpler linear movement of a flat mirror. The mirror scans across the field of view to provide full radial coverage without requiring the camera to rotate, eliminating complex rotational mechanisms.
3Reliability
If opaque well fluid is present in the borehole, then well control is maintained, but optical imaging quality deteriorates
Solution Approach 1:
The imaging process extracts a localized section of the borehole by displacing well fluid only in the immediate vicinity of the tool. This allows optical imaging in a clear fluid environment while maintaining well control in the rest of the well through the packer isolation system.
Solution Approach 2:
A clear fluid acts as an intermediary medium between the opaque well fluid and the optical imaging system. The clear fluid enables light transmission for imaging while the packer system isolates this local clear fluid zone from the rest of the well containing opaque drilling mud.
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
This solution enables clear, undistorted optical imaging of borehole walls with reduced complexity and cost, maintaining well control by using a moveable mirror and clear fluid filling, providing 360° coverage without rotating the camera.
Implementation Method 1
a light source mounted on the tool body and arranged to illuminate the borehole wall
Implementation Method 2
a mirror moveably mounted on the tool body and spaced axially from the camera and arranged to reflect an image of the borehole wall at the camera
Data Source
AI summary
Apparatus for obtaining images of the wall of a borehole, comprises a tool body; a light source mounted on the tool body and arranged to illuminate the borehole wall; a camera mounted in the tool body; and a mirror moveably mounted on the tool body and spaced axially from the camera and arranged to reflect an image of the borehole wall at the camera, wherein the movement of the mirror allows images of different parts of the borehole wall to be reflected at the camera.