Segmented Wellbore Liner for Sidetrack Milling
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Solution Overview
Problem
Milling through wellbore liners made of hard materials for forming lateral wells is time-consuming and causes significant wear on milling tools, due to the high temperatures and pressures encountered in wellbore conditions.
Innovation Solution
A wellbore liner composed of two axial length segments, where the first segment is made of a hard material like steel and the second segment is made of a softer material such as composite or aluminum, allowing the milling BHA to easily mill through the softer segment and reducing tool wear and operation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard material liner is used in the wellbore, then the liner strength and durability under high temperature and pressure is improved, but the milling time and tool wear increase significantly
Solution Approach 1:
The liner is divided into two distinct segments: an upper segment made of hard material (steel or alloy steel) and a lower segment made of softer material (non-metallic composite or aluminum alloy). This segmentation allows each segment to serve its specific function - the hard upper segment provides strength for withstanding wellbore conditions, while the softer lower segment enables easier milling for lateral well formation, thereby resolving the contradiction between liner strength and milling time
Solution Approach 2:
Different material properties are applied to different locations of the liner based on functional requirements. The upper segment near the wellhead uses hard material to withstand high stress and temperature, while the lower segment at the milling location uses softer material to reduce milling resistance. This local differentiation of material quality allows the liner to simultaneously provide strength where needed and ease of milling where required
2Reliability
If a hard material liner is used in the wellbore, then the liner durability is improved, but the wear on milling tools increases significantly
Solution Approach 1:
The liner is segmented into hard upper material for durability and softer lower material for reduced tool wear, allowing the milling operation to occur in the softer segment while the hard segment remains intact to provide overall liner reliability
Solution Approach 2:
The softer material is specifically placed at the lower segment where milling occurs, creating a localized zone of reduced hardness that minimizes tool wear during the milling operation, while the upper segment maintains hard material properties for overall liner durability and reliability
3Strength
If a hard material liner is used in the wellbore, then the liner strength is improved, but the weight of the liner increases
Solution Approach 1:
The liner is divided into segments with different material densities - the upper segment uses denser hard material for strength, while the lower segment uses less dense softer material (non-metallic composite or aluminum alloy) that weighs less, thereby reducing overall liner weight while maintaining necessary strength in the upper portion
Solution Approach 2:
The liner combines different material types - metal (steel or alloy steel) for the upper segment and non-metallic composite or aluminum alloy for the lower segment. This composite construction allows the liner to achieve necessary strength properties in critical areas while using lighter-weight materials in other areas, reducing overall weight
4Reliability
If a hard material liner is used in the wellbore, then the liner durability is improved, but the debris management from milling becomes more difficult
Solution Approach 1:
The liner is segmented so that the lower portion consists of softer material that mills more easily, producing smaller and less abrasive debris compared to milling hard material. This segmentation facilitates debris removal and management while the upper hard segment maintains liner durability
Solution Approach 2:
The softer material is localized at the milling zone to produce easier-to-manage debris, while the hard material is positioned in the upper segment where it is not milled, thus maintaining liner durability without creating difficult-to-manage debris
Data Source
AI summary
A non-metallic liner for wellbore sidetrack operations is included in a wellbore tool assembly. The assembly includes a wellbore milling bottom hole assembly (BHA) that can mill through a wellbore liner material and material softer than the wellbore liner material. The assembly includes a wellbore liner that can be installed within a main well. The wellbore liner includes a first length segment made of the wellbore liner material and a second length segment axially attached to the first length segment. The second length segment is made of the non-metallic material. A window to form a lateral well is in the second length segment. The assembly includes a whipstock that can be installed within the main well in the first length segment of the wellbore liner after the wellbore milling BHA has milled the second length segment. The whipstock can guide the wellbore milling BHA towards the window.