Segmented Shear Pin Assembly for Downhole Tool Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing single stage cementing process for subterranean wells often results in incomplete cementation, and the staging process, which involves sectioning the casing string, can be complex due to issues with shear pins bending and creating burrs that prevent proper tool actuation.
Innovation Solution
A multiple piece drive pin assembly with a flanged drive pin bushing and a shear pin that defines a shear plane, allowing for a clean break and preventing damage, is used to actuate tools like packers and control cement flow in the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single piece shear pin is used to connect inner and outer sleeves, then the device complexity is reduced, but the reliability deteriorates due to bending and burr formation that prevent proper tool actuation
Solution Approach 1:
The drive pin is segmented into multiple pieces: an inner pin portion and an outer bushing. The inner pin shears at a controlled plane while the outer bushing remains intact to guide the inner pin, preventing bending and burr formation that would compromise tool actuation reliability.
Solution Approach 2:
The outer bushing acts as an intermediary between the inner pin and the surrounding environment. It provides a guiding surface that constrains the inner pin's movement path, preventing lateral bending during shear and ensuring clean separation without burrs that could interfere with tool actuation.
2Ease of manufacture
If a single piece shear pin is used, then the manufacturing process is simpler, but the manufacturing precision deteriorates due to bending and burr formation
Solution Approach 1:
The drive pin is divided into an inner pin and outer bushing components. This segmentation allows the inner pin to be designed with a controlled shear plane that shears cleanly, while the outer bushing provides guidance to prevent bending, ensuring high shear surface quality without compromising manufacturing simplicity.
Solution Approach 2:
The outer bushing is installed beforehand to establish a guiding constraint before the inner pin undergoes shear. This preliminary action of positioning the bushing ensures that when the inner pin shears, it follows a predetermined path that prevents bending and produces a clean shear surface.
3Device complexity
If a single piece shear pin is used, then the device structure is simpler, but the harmful factors increase due to bending and burr formation that damage tools
Solution Approach 1:
The potential harm of burr formation and bending is converted into a benefit by using the outer bushing as a guiding constraint. The bushing transforms what would be uncontrolled deformation into a controlled shear process, where the inner pin bends along a predetermined safe path guided by the bushing, preventing damage to surrounding tools.
Solution Approach 2:
The outer bushing serves as an intermediary that absorbs and redirects the harmful effects of shear deformation. By providing a guiding surface, it prevents the inner pin from bending uncontrollably or forming burrs that could damage tool surfaces, thereby eliminating the harmful factors while maintaining structural simplicity.
Data Source
AI summary
A downhole tool for use in a well comprising a mandrel and an outer sleeve slidably disposed about the mandrel. An inner sleeve is slidably disposed in the mandrel. A drive pin comprising a drive pin bushing connected to the outer sleeve and a shear pin connected to the inner sleeve connects the inner sleeve to the outer sleeve.