Electrolytic Downhole Milling for Dual-Casing Section Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current downhole milling tools are inefficient in removing entire sections of metal casing and cement from wellbores, particularly in dual-string wells, and often require rig-based operations, limiting their applicability and efficiency.
Innovation Solution
A downhole tool combining electrolytic milling with electromechanical milling, using conductive elements to corrode metal tubing and abrasive elements to remove material, allowing for standalone operation or integration into modular tools, which can operate from the surface or subsea, and includes features like expandable rails, clamping modules, and fluid circulation systems for optimized corrosion and material removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional electromechanical milling tools are used to remove metal casing sections, then material removal capability is achieved, but operational efficiency is reduced and rig-based operations are required
Solution Approach 1:
The patent combines electrolytic milling and electromechanical milling into a single integrated tool assembly. The electrolytic milling section uses conductive elements and electrolyte circulation to chemically dissolve metal casing, while the electromechanical milling section uses rotating cutters for mechanical removal. This merging allows the tool to handle both cement and metal casing efficiently in dual-string wells, eliminating the need for separate operations and improving overall productivity without requiring rig-based operations.
2Productivity
If electrolytic milling is used to corrode metal tubing, then material removal efficiency is improved, but device complexity increases due to additional systems required
Solution Approach 1:
The tool is divided into distinct functional sections: an electrolytic milling section with conductive elements and electrolyte circulation system, and an electromechanical milling section with rotating cutters. This segmentation allows each subsystem to be optimized independently while working together to solve the overall problem of removing both cement and metal casing, managing device complexity through modular functional division.
Solution Approach 2:
The integrated tool assembly serves multiple functions: the electrolytic section corrodes metal tubing efficiently, the electromechanical section mechanically removes material and cleans surfaces, and the combination enables the tool to handle both cement and metal casing removal in dual-string wells, providing universal applicability for different well abandonment scenarios.
3Reliability
If dual casing string milling is performed, then complete wellbore isolation is achieved, but operational time and cost increase
Solution Approach 1:
The patent merges electrolytic and electromechanical milling capabilities into a single tool that can operate in one continuous operation. The electrolytic section handles metal casing corrosion while the electromechanical section handles cement removal, allowing complete dual-string wellbore isolation to be achieved in a single deployment rather than requiring multiple separate operations, thereby reducing operational time and cost while maintaining isolation integrity.
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 removal of metal tubing and cement sections without the need for a rig, allowing for plug and abandonment operations and other applications like side-tracking, with improved control and reduced operational costs by using a combination of electrolytic and mechanical milling methods.
Implementation Method 1
at least one conductive element being arranged to corrode a section of metal tubing using an electrolytic process
Implementation Method 2
a milling apparatus with cutting or abrasive elements arranged to remove byproducts from the electrolytic process
Data Source
AI summary
The present invention relates to a downhole tool (23), for removing sections of metal tubing, comprising: at least one conductive element (1) being arranged to corrode a section of metal tubing using an electrolytic process, said conductive element (1) being a tube or a pipe which is made of electric conductive material, an apparatus (4) to establish a connection to the metal tubing (2), and a milling apparatus with cutting or abrasive elements (3) arranged to remove byproducts from the electrolytic process. The invention also relates to a modular downhole tool (45), comprising an elongated main shaft (8) with several modules for insertion in a wellbore.