Slot Recovery via Lateral Casing Segmentation
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Solution Overview
Problem
Current slot recovery methods in offshore drilling are either time-consuming and expensive or risk costly collisions with nearby boreholes, making them economically and environmentally inefficient.
Innovation Solution
A method involving running an internal cutter to laterally cut through existing casings, using a hollow drill bit to drill around the outermost casing, and attaching a removal tool to extract casings, allowing for efficient removal while minimizing collision risks and maintaining well integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the milling method is used to remove intermediate casings, then the casings can be removed, but the operation becomes very time consuming and expensive
Solution Approach 1:
The invention segments the casing removal process into distinct phases: cutting the casing string at predetermined depths, removing casings section by section using a spear tool, and drilling around outer casings. This segmentation allows for systematic removal without requiring complete milling of all casings, thereby reducing time and cost while maintaining reliability.
Solution Approach 2:
Instead of removing casings from the inside out through milling, the invention inverts the approach by cutting casings laterally and removing them from the outside in using a spear tool that engages the cut casing sections. This inversion enables faster removal by avoiding the time-consuming process of milling through entire casing strings.
2Reliability
If a deflecting tool such as a whipstock is used to drill a new well, then the conductor casing can be removed, but there is high risk of collisions with neighbouring well bores
Solution Approach 1:
The invention performs preliminary cutting of the conductor casing at predetermined depths before attempting removal. By pre-cutting the casing string into manageable sections and preparing removal points in advance, the operation can proceed more controlled and precisely, reducing the risk of unintended deflections or collisions with neighboring bore holes during the removal process.
3Adaptability or versatility
If all casings are removed to enable slot recovery, then the slot can be reused, but the operation becomes more complex and time consuming
Solution Approach 1:
The invention applies local quality by selectively removing only the necessary casing sections required for slot recovery while leaving other casings in place where possible. The method allows for targeted removal of intermediate and conductor casings at specific depths using predetermined cut points, rather than requiring removal of all casings throughout their entire length. This selective approach reduces process complexity while maintaining slot reuse capability.
Data Source
AI summary
The present concept is a method of slot recovery for the oil industry. The method involves running an internal cutter down the production casing to cut through a preselected number of existing casings at predetermined depths before drilling around the outermost preselected casing with a hollow drill bit. The hollow drill bit drills through the preslected outermost casing cement to the predetermined depth before a removal tool attached to the inside of the production casing is used to remove the existing casings to the predetermined depth. These steps are repeated using appropriately sized hollow drill bits and casings to drill around the next preselected outermost casings to the next predetermined depth, continuously removing the existing casings until all desired existing casings are removed.