Composite Downhole Cable Structure for Lower Weight and Friction
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Solution Overview
Problem
Current downhole cables, such as wireline and slickline cables, are heavy due to their metallic construction, requiring significant energy to deploy and operate, and are prone to breaking under their own weight, especially when reaching deep wells.
Innovation Solution
A cable design featuring a core surrounded by a plurality of reinforcing elements, each comprising a bundle of reinforcement fibers impregnated with a thermoset matrix and individually coated with a thermoplastic coating, allowing the reinforcing elements to move relative to each other and the core, thereby reducing weight and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic armor wires are used to reinforce the cable, then the mechanical strength is improved, but the weight of the cable increases significantly
Solution Approach 1:
The patent replaces traditional metallic armor wires with composite reinforcing elements consisting of high-strength fibers (such as aramid or carbon fibers) embedded in a polymer matrix. These composite materials provide comparable or superior mechanical strength while significantly reducing the cable weight, directly resolving the contradiction between strength and weight.
Solution Approach 2:
The invention changes the material parameters from dense metals to lightweight high-strength fibers with specific gravity less than 2.0. This parameter change in material density and composition allows achieving the required mechanical strength with substantially reduced weight, addressing the technical contradiction effectively.
2Strength
If metallic armor wires are used to provide strength, then the cable can withstand mechanical loads, but the friction with the wellbore increases
Solution Approach 1:
The patent changes the surface material parameters from metallic to polymeric/coated surfaces with lower coefficients of friction. The fiber-reinforced polymer construction inherently provides lower friction characteristics compared to metallic armor, reducing the harmful friction effect while maintaining load-bearing capacity through the high strength-to-weight ratio of the composite materials.
3Reliability
If heavy metallic cable is used to ensure mechanical strength, then the cable can support deep well operations, but the energy consumption for deployment increases
Solution Approach 1:
The use of fiber-reinforced composite materials creates a cable that is both lightweight and mechanically robust. The high tensile strength of fibers like aramid or carbon allows the cable to support deep well operations reliably, while the reduced weight minimizes the energy required for deployment and retrieval, resolving the contradiction between reliability and energy consumption.
Solution Approach 2:
The invention changes the density parameter of the cable material from high (metallic) to low (fiber-composite with specific gravity < 2.0). This parameter change reduces the gravitational force acting on the cable, thereby reducing the energy required for deployment while maintaining the necessary mechanical strength for deep well operations through the superior strength properties of the composite materials.
4Strength
If metallic reinforced cable is used to provide structural integrity, then the cable maintains strength, but the risk of breakage under own weight increases for deep wells
Solution Approach 1:
The patent employs fiber-reinforced composite materials that offer superior tensile strength and elasticity compared to metallic cables. The high strength-to-weight ratio of these composites reduces the cable's self-load, minimizing the risk of breakage under its own weight during deep well operations while maintaining excellent structural integrity through the composite architecture.
Solution Approach 2:
The invention changes the material parameters to include high-tensile-strength fibers with low density. This parameter change in material composition and mechanical properties allows the cable to support itself over greater lengths without breaking, thereby improving reliability for deep well applications while preserving structural integrity through the composite material system.
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 cable achieves reduced weight and friction, enabling more efficient downhole operations with lower energy consumption and increased durability, allowing for deeper well penetration without risk of cable breakage.
Implementation Method 1
a thermoset matrix impregnating the bundle of fibers
Implementation Method 2
extruding a thermoplastic coating around each reinforcing element of the plurality so as to form a tube around each reinforcing element
Implementation Method 3
curing the thermoset matrix of the tubed reinforcing element once arranged around the core
Data Source
AI summary
The disclosure relates to a cable (100) comprising a core (102) and a plurality of reinforcing elements (107) arranged around the core (102) so as to cover the core (102), wherein each reinforcing element (107) includes at least a bundle of reinforcement fibers comprising at least one fiber and a thermoset matrix impregnating the bundle of fibers, wherein each reinforcing element (107) is individually tubed with a thermoplastic coating (112).