Underreamer Cutter Block Height Ratio for Single-Run Bore Enlargement
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Solution Overview
Problem
Conventional underreamers require multiple runs to achieve significant wellbore diameter increases, which is time-consuming and costly, as they can only enlarge the wellbore diameter by 15% to 25% per run.
Innovation Solution
An underreamer design with a cylindrical body and a mandrel, featuring cutter blocks that transition from a retracted to an expanded state, allowing for a height-to-diameter ratio of 0.35:1 to 0.50:1, enabling a larger diameter increase of up to 70% in a single run by positioning the cutter blocks radially outward from the body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional cutter blocks with height-to-diameter ratio of 0.15:1 to 0.25:1 are used, then the underreamer can be run into the wellbore, but the wellbore diameter can only be increased by 15% to 25% per run, requiring multiple runs
Solution Approach 1:
The patent changes the key parameter of cutter block height, increasing the height-to-diameter ratio from conventional 0.15:1 to 0.25:1 to a new range of 0.35:1 to 0.50:1. This parameter change enables the cutter blocks to increase wellbore diameter by up to 70% in a single run, eliminating the need for multiple runs while maintaining structural integrity
Solution Approach 2:
The cutter blocks are designed to transition dynamically between a retracted state (during run-in) and an expanded state (during reaming). This dynamic capability allows the same tool to accommodate both transportation constraints and large-diameter enlargement requirements, resolving the contradiction between cutter block height and device complexity
2Productivity
If multiple underreamers are run into the wellbore to achieve larger diameter increases, then the wellbore diameter can be increased further, but the process becomes time-consuming and leads to lost profits
Solution Approach 1:
By changing the cutter block height parameter to achieve a height-to-diameter ratio of 0.35:1 to 0.50:1, the underreamer can increase wellbore diameter by up to 70% in a single run. This single-run capability eliminates the time loss associated with multiple runs while maintaining high productivity
Solution Approach 2:
The extended cutter block height enables continuous useful action by allowing the underreamer to achieve the full required diameter increase in one continuous operation rather than requiring multiple discrete runs, thereby eliminating idle time between runs
Data Source
AI summary
An underreamer for increasing the diameter of a bore. The underreamer includes a substantially cylindrical body having an axial bore therein. A mandrel may extend axially through the axial bore. One or more cutter blocks are movably coupled to the body. A ratio of a height of the cutter block to a diameter of the body is between about 0.35:1 and about 0.50:1.