Composite Slickline Cable Shape Control During Heat Curing
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Solution Overview
Problem
Slickline cables used in the oilfield industry face issues with strength due to low-strength metallic tubes and deformation during heat curing, leading to irregular profiles and vulnerability to failure, as well as manufacturing challenges like jamming and distortion caused by loose fibers and thermal expansion differences.
Innovation Solution
The method involves preparing a slickline cable by applying an epoxy/fiber composite strength layer on an inner metallic tube and using techniques such as passing through progressively smaller diameter dies, infrared heating, and polymer backflow compression extrusion to maintain a uniform circular cross-sectional shape and minimize fiber distortion, ensuring the cable remains round and durable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an epoxy/fiber composite strength layer is applied on an inner metallic tube and heat cured, then the cable gains strength and structural integrity, but the composite deforms into an irregular oval shape due to thermal expansion differences between the epoxy and fibers
Solution Approach 1:
The patent applies a polymer coating to the composite strength layer before heat curing. This coating layer acts as a constraint that prevents the composite from deforming into an oval shape during the heat curing process. The polymer coating maintains the circular cross-sectional shape by compensating for the differential thermal expansion between the epoxy and fibers, thus resolving the contradiction between gaining strength through heat curing and maintaining shape uniformity.
2Shape
If the composite layer profile is corrected by compression extruding a polymer layer, then the circular shape is maintained, but the extrusion process causes jamming and interruption due to loose fibers collecting at the extruder tip
Solution Approach 1:
The patent applies the polymer coating to the composite strength layer before heat curing, rather than attempting to correct the profile after heat curing through compression extrusion. This preliminary application of the polymer coating prevents loose fibers from collecting at the extruder tip during the coating process, as the coating is applied in a controlled manner before the composite sets. This eliminates the jamming problem that occurs with post-curing compression extrusion, maintaining both circular profile uniformity and manufacturing continuity.
3Shape
If compression extrusion is used to correct the composite profile, then the circular shape is maintained, but the reheating releases moisture and volatiles causing blistering of the extruded polymer
Solution Approach 1:
The patent applies the polymer coating to the composite strength layer before heat curing, rather than after. This timing is critical because it allows the polymer coating to be applied to a cooler surface that has not yet been heated to high temperatures. The coating is then cured along with the composite in a controlled manner, preventing the release of moisture and volatiles that would cause blistering. This preliminary application approach maintains both circular profile uniformity and polymer surface quality without the need for subsequent reheating and compression extrusion.
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
This approach results in a durable and reliable slickline cable with minimal diameter variation and a consistent circular profile, reducing the risk of failure and improving manufacturing efficiency by preventing jamming and maintaining cable strength during deployment.
Implementation Method 1
the epoxy/long fiber composite 106 and the metal forming the tubes 104 have significantly different thermal coefficients, the epoxy/long fiber composite 106 tends to deform during heat curing (at 400° to 500° F.) into a slightly irregular oval shape
Implementation Method 2
passing the combination through an infrared heater to remove and volatiles from the epoxy
Implementation Method 3
polymer backflow compression extrusion to maintain a uniform circular cross-sectional shape
Data Source
AI summary
Disclosed are wellbore electric cables, and methods of manufacturing such cables, and in one aspect, methods of manufacturing wireline composite slickline cables. Some embodiments are methods which include preparing a slickline cable by providing an inner metallic tube containing at least one conductor (such as an optical fiber), disposing an epoxy/fiber composite strength layer substantially upon the outer periphery of the inner metallic tube, and exposing the combination of the inner metallic tube and composite strength layer to at least one technique for minimizing the variation in diameter and providing a substantially uniform circular cross-sectional shape of the combination. Further, an outer metallic tube is draw around the combination of the composite strength member and the inner metallic tube, to form a wellbore slickline. Cables prepared using such methods are also disclosed.