Degradable Casing Window for Sidetracking
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Solution Overview
Problem
The traditional method of sidetracking a wellbore requires multiple tool assemblies and steps, and the milling process generates mill cuttings from the casing material, necessitating an additional tool trip and being inefficient.
Innovation Solution
A system and method using a pH-modifying fluid to degrade a portion of the casing string, creating a window for a secondary wellbore, where a whipstock and packer guide the fluid to a degradable section of the casing, minimizing contact with unintended equipment and casing material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a milling assembly is used to create the window by drilling through the casing strings, then the window can be created, but it requires an additional trip of disposing a separate tool downhole and creates mill cuttings from the casing material
Solution Approach 1:
The patent replaces the mechanical milling process with a chemical dissolution process. Instead of using a milling assembly that mechanically drills through the casing, the invention uses a dissolvable window made of material that can be chemically dissolved by formation fluids or injected chemicals, eliminating the need for mechanical cutting tools and cuttings removal
Solution Approach 2:
The invention extracts the problematic milling operation from the sidetracking process entirely. By pre-installing a dissolvable window section in the casing before the original well completion, the complex milling assembly and cuttings removal operations are eliminated, leaving only the simpler process of injecting dissolution chemicals
2Productivity
If a milling assembly is used to create the window, then the window can be created, but it creates mill cuttings from the material of the casing strings requiring additional tool trip
Solution Approach 1:
The dissolvable window is pre-installed in the casing during the original well construction before the well is completed and before the sidetracking operation is needed. This preliminary action eliminates the need for later milling operations and cuttings removal, significantly reducing the time required for the actual sidetracking operation
3Ease of operation
If traditional sidetracking methods are used, then the window can be created, but multiple tool assemblies and steps are required that take time for completing the operation
Solution Approach 1:
The invention extracts and removes the complex milling assembly, whipstock positioning equipment, and cuttings removal tools from the sidetracking operation. The only equipment needed is a simple injection system to deliver dissolution chemicals to the pre-installed dissolvable window, dramatically simplifying the operation
Solution Approach 2:
The dissolvable window acts as an intermediary element that facilitates the sidetracking operation without requiring complex tools. Instead of using complex mechanical tools to create the window, the system uses a passive dissolvable structure that is activated by chemical injection, serving as a mediator between the injection system and the final window creation
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 approach reduces the complexity and time required for sidetracking by creating a window efficiently, allowing for precise control of the degradation process and minimizing material waste, enabling faster exploration of new formations.
Implementation Method 1
A method for creating a window in an oilfield tubular may include providing a pH-modifying fluid in the oilfield tubular disposed in a wellbore; and contacting a degradable section of the oilfield tubular with the pH-modifying fluid to degrade at least a portion of the degradable section and form an exit window in the oilfield tubular
Data Source
AI summary
This disclosure may generally relate to drilling operations and, more particularly, to systems and methods for sidetracking an existing well. Specifically, examples of the present disclosure may include creating a window by introducing a pH-modifying fluid downhole to degrade a portion of a casing string, thereby creating the window through which a secondary wellbore may be drilled. A method for creating a window in an oilfield tubular may comprise of providing a pH-modifying fluid in the oilfield tubular disposed in a wellbore and contacting a degradable section of the oilfield tubular with the pH-modifying fluid to degrade at least a portion of the degradable section and form an exit window in the oilfield tubular.