ESP Shaft Tethering Assembly for Component Retrieval Safety
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Solution Overview
Problem
Extended operation of electric submersible pump (ESP) assemblies in harsh downhole environments leads to component separation during retrieval, causing safety hazards and costly fishing operations to recover fallen parts.
Innovation Solution
A tethering assembly using a tie rod system that couples drive shafts of ESP components, allowing axial motion while preventing uncontrolled falls by setting a mechanical limit, thereby securing separated components and facilitating safer retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If ESP assembly components are operated for extended periods in harsh downhole environments, then productivity is improved through continuous operation, but reliability deteriorates due to component separation during retrieval
Solution Approach 1:
The patent applies preliminary action by installing the tethering assembly (tie rod with coupling elements) on the drive shaft before the ESP assembly is deployed into the wellbore. This pre-installation ensures that the protective tethering mechanism is already in place to prevent component separation during future retrieval operations, addressing the reliability issue before it can manifest.
Solution Approach 2:
The tethering assembly acts as an intermediary element between the drive shaft components. The tie rod with its coupling elements serves as a mediating structure that physically connects and restrains adjacent ESP components, preventing them from separating during retrieval while allowing the components to function independently during operation.
2Device complexity
If traditional drive shaft coupling is used without tethering, then device complexity is minimized, but safety hazards increase due to uncontrolled falls of separated components
Solution Approach 1:
The tethering assembly is segmented into distinct functional elements: the tie rod body, first coupling element for attaching to the upper drive shaft, and second coupling element for attaching to the lower drive shaft. This segmentation allows each component to be optimized independently while maintaining overall simplicity of the complete assembly.
Solution Approach 2:
The tethering assembly is designed as a simple, robust mechanical device that can be easily manufactured and installed. While it provides long-term safety protection, the design prioritizes simplicity and ease of installation over complex reusable mechanisms, aligning with the principle of using straightforward structural solutions for safety functions.
3Loss of time
If component separation occurs during retrieval, then loss of time increases due to costly fishing operations, but the tethering assembly adds structural complexity to prevent separation
Solution Approach 1:
By pre-installing the tethering assembly before ESP deployment, the patent eliminates the need for time-consuming fishing operations if component separation occurs. The preliminary installation of this simple mechanical restraint prevents the scenario that would lead to loss of time, making the small added complexity worthwhile by avoiding major retrieval operations.
Solution Approach 2:
The tethering assembly provides beforehand cushioning by being in place before any separation can occur. It acts as a pre-deployed safety mechanism that cushions against the harmful effect of component separation, preventing the need for expensive and time-consuming fishing operations to recover separated parts.
Data Source
AI summary
A method of lifting fluid by an electrical submersible pump (ESP) assembly in a wellbore. The method comprises positioning a first ESP component above the wellbore, wherein the first ESP component comprises a first drive shaft; positioning a second ESP component above the first ESP component, wherein the second ESP component comprises a second drive shaft; coupling a tethering assembly at a first end to an end of the first drive shaft proximate to the first flange; passing the tethering assembly through a coupling shell; coupling a second end of the tethering assembly to an end of the second drive shaft proximate to the second flange, wherein the tethering assembly is coupled slidingly to the first drive shaft or to the second drive shaft; coupling the first drive shaft to the second drive shaft by the coupling shell; and coupling the first flange to the second flange.