Downhole Heating Cable Support via Nested Coiled Tubing
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Solution Overview
Problem
Existing downhole heater installations for oil and gas wells are time-consuming and expensive, and existing methods for supporting heating cables within coiled tubing are not suitable for mineral insulated cables or do not maintain grip after thermal cycling.
Innovation Solution
A downhole heating apparatus with electric heating cables, an elongated support member, and a cable hang-off system that uses a shell with slips to grip and suspend the support member, along with cable support clamps to attach the support member to the cables, providing mechanical support and maintaining grip even after thermal cycling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heater cables are clamped to the exterior of production tubing, then heating function is achieved, but complete workover operation is required which is time-consuming and expensive
Solution Approach 1:
The heater cables are nested inside the coiled tubing rather than being clamped externally. The coiled tubing acts as a protective conduit that contains the heater cables, allowing the entire assembly to be deployed through the production tubing without requiring workover operations. This nesting approach simplifies installation while maintaining heating functionality.
Solution Approach 2:
The heater cables are extracted from the traditional external clamping configuration and repositioned inside the coiled tubing. This extraction allows the heating system to be installed through the production tubing using existing wellhead equipment, eliminating the need for workover operations and reducing installation complexity.
2Reliability
If heater cables are exposed to well fluids, then heating function is maintained, but chemical exposure causes degradation and failure
Solution Approach 1:
The heater cables are nested inside the coiled tubing, which serves as a protective barrier. This nested configuration isolates the heater cables from direct contact with well fluids while maintaining their heating function, as the coiled tubing acts as a chemical-resistant conduit.
Solution Approach 2:
The coiled tubing acts as an intermediary barrier between the heater cables and the well fluids. It provides chemical protection to the heater cables while still allowing thermal energy to transfer to the surrounding environment, thus protecting the cables without compromising their heating function.
3Ease of operation
If simple banding materials are used to support cables, then installation is simple, but bands come loose after thermal cycling
Solution Approach 1:
The cable support mechanism uses clips with adjustable gripping force that can accommodate thermal expansion and contraction. The clips are designed to maintain secure attachment through thermal cycling by allowing parameter changes in their gripping mechanism, ensuring reliable cable support while remaining easy to install.
Solution Approach 2:
The cable support system uses composite construction with clips made from materials that have different thermal expansion properties than the cables. This composite approach allows the support mechanism to maintain grip during thermal cycling while keeping the installation process simple and straightforward.
4Object-affected harmful factors
If electric cables are deployed independently within tube, then cable protection is achieved, but cables lack sufficient tensile strength for long vertical sections
Solution Approach 1:
The heater cables are merged with a high-strength support rope or wire inside the coiled tubing. This combined assembly provides both the electrical heating function and the mechanical tensile strength needed for long vertical deployments. The support element carries the mechanical load while the heater cables provide the heating function.
Solution Approach 2:
A high-strength support rope or wire acts as an intermediary element that provides tensile strength to the heater cable assembly. This mediator carries the mechanical load for long vertical sections while allowing the heater cables to remain protected inside the coiled tubing, combining protective enclosures with strength enhancement.
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 efficient and cost-effective installation of heating cables within coiled tubing, protecting them from well fluids and maintaining mechanical support, allowing for improved heat transfer and reduced installation time and costs.
Implementation Method 1
heat can be delivered to the production tubing in the well via a heater installation in order to heat the oil to be extracted
Implementation Method 2
Deployment of coiled tubing heaters improves heat transfer to a target medium because such coiled tubing heaters provide a larger surface area in contact with said medium
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A downhole heating apparatus comprises one or more electric heating cables (70). It further comprises an elongated support member (76) that receives a mechanical load from the heating cables when the heating cables are suspended vertically within a wellbore by a cable hang-off (56). It also comprises a plurality of cable support clamps (80) that attach the support member to the heating cables and transfer mechanical loads from the heating cables to the support member, the cable support clamps being attached to the support member and to the heating cables at regular intervals along the length of the support member.