Subsea Well Casing Severing and Removal
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Solution Overview
Problem
Conventional subsea well abandonment methods are time-consuming and costly, requiring multiple drill string trips to remove individual well casings and components separately, which increases the risk of safety incidents and equipment downtime.
Innovation Solution
A method and system that utilize a utility line with a cutting tool deployed from a floating vessel to sever multiple well casings concurrently, allowing the wellhead and severed casings to be raised as a single assembly, along with a cement dispensing line to form a plug in the well, reducing the need for multiple trips and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to remove individual well casings separately, then each casing can be removed with existing cutting tool limitations, but the process requires multiple drill string trips which increases time and cost
Solution Approach 1:
The patent combines multiple cutting operations into a single drill string trip by equipping the drill string with multiple cutting tools or a cutting tool capable of cutting through multiple casings simultaneously. This merging of operations eliminates the need for multiple separate trips to remove each casing individually, directly resolving the contradiction between ease of manufacture and productivity
Solution Approach 2:
The patent performs preliminary positioning and alignment of multiple cutting tools on the drill string before entering the well. By pre-configuring the cutting tools at appropriate depths and positions, the system can sever multiple casings in one operation without requiring repeated trips, thus improving productivity while maintaining the ability to handle different casing configurations
2Reliability
If multiple drill string trips are required to remove each casing individually, then cutting tool dimensional limitations are respected, but safety incidents and equipment downtime increase
Solution Approach 1:
By combining multiple casing removal operations into a single drill string trip, the patent reduces the number of times equipment must be deployed and retrieved, thereby minimizing equipment downtime and reducing exposure to safety risks associated with repeated subsea operations
Solution Approach 2:
The patent enables continuous operation by removing multiple casings in one uninterrupted drill string trip rather than interrupting the operation multiple times. This continuity reduces equipment downtime and maintains a more consistent safety profile by limiting the frequency of hazardous deployment cycles
3Ease of manufacture
If conventional cutting tools are used, then individual casings can be cut, but the process is costly and time-consuming due to multiple trips
Solution Approach 1:
The patent merges multiple cutting functions into a single drill string assembly, allowing one trip to perform what previously required multiple trips. This reduces the overall complexity of the abandonment process by eliminating repeated deployment and retrieval cycles, even though the drill string itself carries multiple cutting tools
Solution Approach 2:
The drill string is designed with multi-functionality, carrying multiple cutting tools or a cutting tool capable of addressing different casing types and depths. This universal design allows a single drill string trip to handle multiple casing removal tasks that would otherwise require specialized trips for each casing, reducing overall process complexity
Data Source
AI summary
Disclosed are systems and methods for removing components of a subsea well having a wellhead located on a seabed and multiple well casings connected to the wellhead and penetrating the seabed. A cutting tool is lowered from a floating vessel to a predetermined cut location in the subsea well. The cutting tool is at the end of a utility line connected to an actuator located on the floating vessel. The cutting tool is used to sever the multiple well casings at the predetermined cut location such that the multiple well casings are completely severed concurrently. The wellhead and the severed multiple well casings are raised together from the seabed to the floating vessel as a single assembly. Various forms of the cutting tool are disclosed. The methods disclosed can include an integrated procedure for dispensing cement to plug the well at the seabed as the well components are being removed.