Wireline Cable Head Weak Link with Shock Absorber
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Solution Overview
Problem
Existing cable heads for subterranean wells lack effective shock absorption and reliable weak link mechanisms, leading to potential failure under shock loads and difficulty in retrieving wirelines when tool strings become stuck.
Innovation Solution
Incorporating a wire rope shock absorber connected in series with a rigid weak point in the cable head's weak link, which can withstand shock loads and part at a predetermined tensile force, allowing for safe retrieval of the wireline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid weak link is used in the cable head, then the wireline can be retrieved when the tool string becomes stuck, but the cable head cannot withstand shock loads and may break
Solution Approach 1:
The weak link assembly is segmented into distinct functional components: a rigid weak point element (for controlled breaking at predetermined force) and a flexible shock-absorbing element (wire rope or elastomeric material). This segmentation allows each component to perform its specific function - the rigid portion ensures reliable wireline retrieval while the flexible portion provides shock load protection.
Solution Approach 2:
The flexible shock-absorbing element is incorporated into the weak link assembly beforehand to cushion and absorb shock loads before they can cause damage. This pre-installed cushioning mechanism protects the cable head from sudden impact forces during operations like perforating and packer setting, preventing premature failure while maintaining the weak link's ability to break at the predetermined force for wireline retrieval.
2Reliability
If the weak link is designed to break at low tensile force, then wireline retrieval is enabled, but the cable head fails under normal operating shock loads
Solution Approach 1:
The weak link assembly uses a composite structure combining a rigid weak point element (such as a metal link with reduced cross-section) and a flexible shock-absorbing element (wire rope or elastomeric material). This composite design allows the assembly to exhibit both the low breaking force characteristic of the rigid weak point and the shock absorption capability of the flexible element, resolving the contradiction between enabling wireline retrieval and withstanding shock loads.
3Strength
If a shock absorber is added to the weak link, then shock load resistance is improved, but the device complexity increases
Solution Approach 1:
The flexible shock-absorbing element serves multiple functions within the weak link assembly: it absorbs shock loads during normal operations, provides gradual load distribution, and maintains the structural integrity of the assembly. This multi-functionality reduces the need for additional separate shock absorption mechanisms, thereby limiting the increase in device complexity while still providing the necessary shock load resistance.
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
The solution enables the cable head to absorb shock loads without breaking, ensuring reliable retrieval of the wireline and tool string, even in operations like perforating and packer setting, by using a wire rope with greater tensile strength than the rigid weak point.
Implementation Method 1
a flexible shock-absorbing element, such as a wire rope or elastomeric material, connected in series with the rigid weak point
Implementation Method 2
The wire rope has a greater tensile strength than the rigid weak point, ensuring that the wire rope can withstand shock loads without breaking
Data Source
AI summary
A cable head can include an upper connector configured to connect the cable head to a wireline, a lower connector configured to connect the cable head to a well tool, and a weak link configured to transmit tensile force between the upper and lower connectors. The weak link can include a shock absorber connected in series with a weak point. A method of connecting a wireline to a well tool can include securing the wireline to an upper end of a weak link, and securing the well tool to a lower end of the weak link. The weak link includes a wire rope, and end links secured at respective opposite ends of the wire rope. One end link includes a weak point. A weak link for use with a cable head can include a weak point and a shock absorber connected in series with the weak point.