Laser Casing Milling for Cement Repair Without Rig Deployment
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Solution Overview
Problem
Existing methods for repairing leaks and failures in concentric casing strings of oil and gas wellbores, such as those involving mechanical milling or perforation with explosives, are costly, time-consuming, and can damage the surrounding geology, necessitating a more reliable and efficient method.
Innovation Solution
A laser milling system is used to create a window through the innermost casing string and cement column, followed by abrasive jetting to clean out the cement, insertion of a secondary plug material to form a solidified seal, and subsequent drilling to restore the wellbore flowpath, all without requiring a full drilling rig.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical milling or perforation methods are used to repair leaks in concentric casing strings, then the leaks can be sealed, but the surrounding geology is damaged and the operation becomes costly and time-consuming
Solution Approach 1:
The patent replaces traditional mechanical milling and explosive perforation systems with a laser-based system. The laser beam is transmitted through optical fiber to the downhole location, where it ablates the casing and cement materials precisely without mechanical contact, thereby avoiding damage to surrounding geology while effectively creating access channels for leak sealing
Solution Approach 2:
The patent changes the physical state and properties of materials through laser energy application. The laser beam heats and vaporizes casing and cement materials at the target location, creating a clean, precise window for secondary plug insertion without the collateral damage associated with mechanical or explosive methods
2Ease of manufacture
If full drilling rigs are employed for mechanical milling or perforating of casing strings and cement columns, then section milling can be achieved, but the operation becomes costly and time-consuming
Solution Approach 1:
The patent substitutes heavy mechanical drilling rig systems with a laser ablation system delivered via coiled tubing. This eliminates the need for expensive, time-consuming rig deployment while maintaining the capability to mill through casing and cement for repair operations
Solution Approach 2:
The patent extracts only the essential milling function from the complex drilling rig system by using a focused laser beam that can be delivered through flexible coiled tubing. This isolates the useful capability (precise material removal) from the cumbersome equipment infrastructure
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
This method effectively seals leaks and restores the wellbore flowpath, providing a gas-tight seal and alleviating sustained casing pressure, while avoiding the costs and risks associated with traditional methods.
Implementation Method 1
operating a laser milling tool within the wellbore flowpath to discharge a laser beam into the wellbore flowpath to thereby mill a window through the radially innermost casing string and radially outward towards a radially innermost cement column
Implementation Method 2
discharging an abrasive fluid from an abrasive jetting tool into the wellbore flowpath and thereby cleaning out the radially innermost cement column to expand the window radially
Data Source
AI summary
A method includes setting a primary plug within a wellbore flowpath defined through a radially innermost casing string of a plurality of concentric casing strings, operating a laser milling tool within the wellbore flowpath to discharge a laser beam into the wellbore flowpath to thereby mill a window through the radially innermost casing string and radially outward towards a radially innermost cement column of a plurality of respective cement columns surrounding each of the concentric casing strings, discharging an abrasive fluid from an abrasive jetting tool into the wellbore flowpath and cleaning out the radially innermost cement column to expand the window radially, flowing a secondary plug material into the window and the wellbore flowpath above the primary plug, solidifying the secondary plug material to form a solidified secondary plug within the window, and drilling out the solidified secondary plug to restore the wellbore flowpath through the solidified secondary plug.