Surface-Powered Casing Cutter for Eccentric Wellbore Strings
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Solution Overview
Problem
Existing casing cutters for deep wellbore operations are too expensive, large, and cumbersome for cut-and-cap well abandonment processes, requiring stationary drilling rigs and are not suitable for cutting eccentrically nested casings.
Innovation Solution
A mobile, surface-powered casing cutter attachment operably connected to a mobile power source, using hydraulic pistons to pivot cutting elements between retracted and extended positions for cutting casing strings, allowing operation without a stationary drilling rig.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If known casing cutters are used for deep wellbore operations, then cutting capability is achieved, but the equipment becomes too expensive, large, and cumbersome for cut-and-cap operations
Solution Approach 1:
The casing cutter is segmented into modular components including a power source, drive mechanism, and cutting head that can be assembled and disassembled. This segmentation allows for cost-effective manufacturing while maintaining cutting capability through standardized interfaces and interchangeable parts.
Solution Approach 2:
The cutting function is extracted from the complex downhole equipment and placed in a simplified surface-operated device. The cutting head is separated from the need for extensive downhole componentry, allowing the use of less expensive materials and simpler construction while retaining effective cutting capability.
2Strength
If known casing cutters are designed with high tolerances and expensive materials, then resistance to downhole conditions is improved, but the equipment becomes too large and cumbersome for cut-and-cap processes
Solution Approach 1:
High-strength materials and tight tolerances are applied locally only where needed for cutting engagement and structural integrity, rather than throughout the entire device. This allows the cutting elements to resist downhole conditions effectively while the overall equipment remains compact and suitable for cut-and-cap operations.
Solution Approach 2:
The cutter design uses asymmetric distribution of material properties, with hardened, high-strength components concentrated at the cutting interface while other portions use lighter, less expensive materials. This asymmetric approach maintains local strength where required while minimizing overall equipment volume.
3Power
If known cutters require stationary drilling rigs, then cutting power is sufficient, but the equipment is not suitable for operations without stationary rigs
Solution Approach 1:
The power source, drive mechanism, and cutting head are merged into an integrated surface-operated unit. This combination eliminates the need for stationary drilling rigs while maintaining sufficient cutting power through direct mechanical coupling and efficient power transmission from the surface power source.
Solution Approach 2:
The cutter is designed as a universal device that can operate with various power sources and adapt to different wellhead configurations. The multi-functional design allows the same equipment to be used whether or not a stationary drilling rig is available, greatly enhancing operational flexibility.
4Length of moving object
If known cutters are designed for reduced diameter, then they can fit within wellbore size restrictions, but the equipment becomes too complex and expensive for cut-and-cap operations
Solution Approach 1:
The cutting elements are nested within a compact housing that can be inserted into the wellbore in a retracted state. The cutting blades are stored in a nested configuration within the cutter body, allowing the overall diameter to remain small while maintaining the capability to extend cutting elements when needed, without requiring complex stabilization mechanisms.
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
Enables efficient and cost-effective cutting of multiple casing strings at the surface, accommodating eccentric alignments, and eliminating the need for continuous fluid flow and downhole equipment.
Implementation Method 1
fluid pressure differentials within the at least one fluid chamber causes axial movement of the at least one hydraulic piston, pivoting the at least one cutting element from a first retracted position to a second extended position
Implementation Method 2
rotation of the attachment and causes the at least one cutting element to cut the at least one casing string
Data Source
AI summary
An improved casing cutter apparatus and method of use are provided for cutting one or more casing strings positioned within a subterranean wellbore during the ‘cut-and-cap’ stage of the wellbore abandonment process. In some embodiments, the apparatus may comprise a cutting attachment operably coupled to at least one mobile power source located at or near the surface of the wellbore.