Machined Packer Setting Joint for Predictable Burst Strength
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Solution Overview
Problem
In the drilling and completion industry, predicting packer performance in boreholes is challenging due to inconsistent cement jobs in casing strings, requiring extensive finite element analysis and safety factors to compensate for uncertainties in as-rolled casing properties.
Innovation Solution
A downhole system with a machined packer setting joint having greater burst strength than standard casing joints, allowing for predictable packer performance without reliance on cement support, featuring a machined interior and exterior from uphole to downhole ends, connected to the casing string, and equipped with location features for precise placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If as-rolled casing is used for packer installation, then manufacturing cost and ease of installation are improved, but packer performance predictability and reliability deteriorate due to inconsistent casing properties
Solution Approach 1:
The casing string is segmented into standard as-rolled casing sections and a specific machined packer setting joint section. This segmentation allows the majority of the casing to remain simple and easy to install, while only the specific section requiring packer installation undergoes machining to ensure consistent dimensions and predictable packer performance.
Solution Approach 2:
The packer setting joint has locally improved quality through machined surfaces with controlled tolerances, while the rest of the casing maintains standard as-rolled properties. This local quality enhancement ensures reliable packer performance at the installation point without requiring the entire casing string to be machined, balancing reliability with manufacturing ease.
2Reliability
If cement support is required for packer operation, then packer rating and reliability are improved, but the complexity of achieving proper cement jobs and the time required for cementing operations increase
Solution Approach 1:
The packer setting joint is designed to provide self-support for the packer through its machined surfaces and structural configuration. The joint itself serves as the support structure, eliminating the need for external cement support. This self-service approach simplifies the overall system by removing the cementing requirement while maintaining packer reliability.
3Measurement precision
If extensive finite element analysis and testing are performed on as-rolled casing, then packer performance prediction is improved, but time and cost increase significantly
Solution Approach 1:
Instead of performing extensive FEA and testing on variable as-rolled casing, the invention uses a machined copy or replica (the packer setting joint) with controlled, consistent dimensions. This machined joint replicates the essential function of supporting the packer but with predictable geometry, eliminating the need for repeated testing and analysis of natural variations in as-rolled casing.
Data Source
AI summary
A downhole system including tubular casing string and a packer setting joint configured to receive a packer therein. The packer setting joint includes an interior and an exterior, and all interior and exterior surfaces from an uphole to a downhole end of the packer setting joint are machined surfaces. The uphole end of the packer setting joint is connected to the casing string, and the downhole end of the packer setting joint is connected to the casing string. The packer setting joint has a greater burst strength than a burst strength of a casing joint connected to the packer setting joint within the casing string.