Wireline Cable Pressure Control Assembly with Recirculating Lubrication
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Solution Overview
Problem
Existing wellsite surface equipment, particularly wireline cables, face issues with pressure control and sealing due to tight tolerances, armor wire crossover, and contamination from sand and rocks, leading to inefficient sealing and high grease consumption, with traditional flow tubes being cumbersome and prone to damage.
Innovation Solution
A pressure control assembly with a housing frame and sealing devices, including lubricant recirculation and actuated line wipers with chevron-shaped profiles and reinforcement, to maintain pressure and seal wireline cables effectively, reducing the need for flow tubes and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight tolerances (0.003 to 0.005 inches) are used between flow tubes and cable exterior, then sealing effectiveness is improved, but armor wire crossover, milking, and bird caging occur due to cable profile inconsistencies
Solution Approach 1:
The patent replaces rigid flow tubes with flexible packers that can conform to cable profile variations. The packers use elastomeric materials that provide sealing through compression rather than tight dimensional tolerances, eliminating armor wire issues while maintaining seal integrity.
Solution Approach 2:
The invention changes the sealing mechanism from dimensional tolerance-based (rigid) to pressure-based (flexible). By using compressible elastomeric packers, the system accommodates cable diameter variations without requiring precise tolerances, thus preventing armor wire damage.
2Reliability
If flow tubes are placed high above the well floor at inaccessible locations, then pressure control is achieved, but maintenance and accessibility become difficult requiring personnel baskets
Solution Approach 1:
The patent divides the pressure control system into modular components with the packer assembly positioned at accessible locations near the well floor. This segmentation allows maintenance personnel to easily access and service the equipment without requiring elevated platforms or baskets.
Solution Approach 2:
The invention introduces a surface-mounted pressure control assembly that acts as an intermediary between the wellbore pressure and the cable. This assembly can be positioned at accessible locations while still effectively controlling pressure, eliminating the need for high-placed flow tubes.
3Adaptability or versatility
If conventional wireline cables with uneven profiles are used, then cable flexibility is maintained, but flow tube tolerances must be increased causing inefficient sealing and high grease consumption
Solution Approach 1:
The elastomeric packers naturally conform to the cable's uneven profile through their flexible material properties. This eliminates the need for tight tolerances and reduces grease consumption by creating an effective seal without excessive compression or gaps.
Solution Approach 2:
The packer design allows different regions of the sealing surface to adapt locally to cable profile variations. The elastomeric material provides varying compression levels across the sealing interface, maintaining effective sealing while accommodating cable inconsistencies.
4Reliability
If smooth-profile cables are used with rubberized cylindrical packers, then sealing is improved, but the packers become damaged with prolonged use especially on tapered ends
Solution Approach 1:
The patent uses composite construction for the packers, combining elastomeric sealing elements with reinforcement layers. This composite structure maintains sealing effectiveness while significantly improving durability and resistance to damage during prolonged use.
Solution Approach 2:
The reinforced packer design anticipates and prevents damage before it occurs. The strengthened construction, particularly at tapered ends, provides inherent protection against the wear and mechanical stresses of prolonged operation.
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 assembly provides a flexible, durable seal with reduced grease consumption, faster cable operations, and improved maintainability, avoiding cable sticking and armor wire issues, while maintaining a consistent pressure and reducing rig-up and rig-down times.
Implementation Method 1
a lubricant recirculation system for injecting and recirculating a lubricant into the chamber, the assembly operable to lubricate the cable
Implementation Method 2
the sealing devices defining an aperture for a cable to pass therethrough and a chamber therebetween... maintain a predetermined pressure within the housing frame
Data Source
AI summary
An embodiment of a pressure control assembly for a wireline cable disposed in a wellbore comprises a housing frame, at least a pair of sealing devices disposed in the housing, the sealing devices defining an aperture for a cable to pass therethrough and a chamber therebetween, and a lubricant recirculation system for injecting and recirculating a lubricant into the chamber, the assembly operable to lubricate the cable and seal the cable, and maintain a predetermined pressure within the housing frame while the cable is disposed therein.