Downhole Cutting Tool Eccentric Reamer Design
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Solution Overview
Problem
Conventional eccentric reamers are not suitable for use with drill bits during drilling operations, especially when rotated by downhole motors, as they cannot effectively remove ledges and sharp corners in boreholes and often require additional trips to ream the hole, increasing drilling time and costs.
Innovation Solution
A downhole cutting tool with a tubular body featuring uphole and downhole reamer sections, each with radially extending blades and cutter elements, allowing for simultaneous drilling and reaming without damaging the casing, and capable of passing through the borehole without rotating within the casing to avoid damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional eccentric reamer is used to remove ledges and sharp corners, then borehole quality is improved, but the reamer cannot be used simultaneously with the drill bit during drilling operations, requiring additional trips
Solution Approach 1:
The patent combines the drill bit and reamer into a single integrated tool assembly, allowing drilling and reaming functions to be performed simultaneously. The reamer section is coupled to the drill bit such that both tools can be lowered into the borehole together and rotated simultaneously, eliminating the need for separate trips to ream the hole after drilling.
Solution Approach 2:
The integrated tool assembly performs multiple functions: the drill bit drills the borehole while the reamer section simultaneously reams the borehole to remove ledges and sharp corners. This multi-functional design allows a single tool to complete both drilling and reaming operations that would traditionally require separate tool changes and trips.
2Manufacturing precision
If an eccentric reamer is used to ream the borehole, then ledges and sharp corners are removed, but the reamer may damage the casing and cutter elements on the reamer blades
Solution Approach 1:
The reamer section is designed with specific local characteristics: the blades are positioned and angled to engage the borehole sidewall at optimal points, and the cutter elements are strategically placed to remove ledges and sharp corners without excessive force on the casing. The eccentric geometry is optimized to provide effective reaming while minimizing harmful interactions with the casing and cutter elements.
3Ease of operation
If a non-expanding reamer with the same or smaller diameter than the drill bit is used, then the reamer can pass through the borehole, but the reamer will generally follow the path of the drill bit and may not be effective in removing ledges and sharp corners
Solution Approach 1:
The reamer section employs an eccentric geometry where the rotation axis is deliberately offset from the center of the reamer body. This asymmetric design causes the reamer to cut at a different radius than the drill bit diameter, creating an eccentric reamed path that effectively removes ledges and sharp corners while still allowing the tool to pass through the borehole. The eccentricity parameter is optimized to balance passage capability with effective reaming.
Data Source
AI summary
A tool for reaming a borehole includes a tubular body having a central axis, an uphole reamer section mounted to the body, and a downhole reamer section mounted to the body. Each reamer section includes a first blade extending radially from the body. Each blade has an uphole end, a downhole end opposite the uphole end, and a formation-facing surface. The formation facing surface of the first blade of the uphole reamer section is disposed at a radius R1 that increases moving from the uphole end to the downhole end. The formation facing surface of the first blade of the downhole reamer section is disposed at a radius R1′ that decreases moving from the uphole end to the downhole end. The tool also includes a cutter element mounted to the formation facing surface of the first blade of each reamer section.