Inductive Power Transmission in Short-Circuited Wells
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Solution Overview
Problem
Existing technologies for signal and power transmission in hydrocarbon production wells face challenges, particularly in wells where the production pipe and casing are short-circuited at the surface and downhole, requiring efficient methods for replacing sensors and equipment inside the production pipe without using long cables and ensuring low ohmic losses for effective power and signal transmission.
Innovation Solution
A closed electrical circuit is formed by short-circuiting the production pipe and casing at the hanger and packer, using concentric primary and secondary coils with alternating current generators, allowing inductive coupling for power and signal transmission through the well, with coils having ferromagnetic cores to enhance coupling, and enabling replacement of equipment inside the production pipe via light well maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equipment is permanently installed inside the production pipe, then reliable power and signal transmission is achieved, but well intervention requires comprehensive operations
Solution Approach 1:
The system divides the well into multiple electrically isolated zones using insulating packers, allowing equipment in upper zones to be replaced independently without affecting lower zones. Each zone can be accessed and serviced separately through the production pipe, enabling light well intervention rather than comprehensive operations.
Solution Approach 2:
Inductive coupling through the production pipe wall serves as an intermediary mechanism for power and signal transmission. This eliminates the need for direct electrical connections that would require cable replacement, allowing equipment to be changed without disturbing the electrical transmission system.
2Ease of operation
If long cables are used for power and signal transmission, then equipment can be supplied in short-circuited wells, but ohmic losses increase
Solution Approach 1:
The system replaces direct electrical conduction through cables with inductive coupling through the production pipe wall. This substitution eliminates the need for long cables running through the well, thereby eliminating the associated ohmic losses while maintaining power and signal transmission capability.
Solution Approach 2:
The electrical connection is extracted from the interior of the production pipe by using inductive coupling through the pipe wall. This removes the cable from the system entirely, eliminating the source of ohmic losses while maintaining the ability to transmit power and signals to downhole equipment.
3Loss of energy
If the production pipe and casing are electrically isolated, then inductive coupling can be implemented, but the well structure becomes more complex
Solution Approach 1:
The electrical isolation function is copied to existing well components (packers and hangers) rather than requiring dedicated isolation structures. These components are modified to provide both mechanical support and electrical isolation, reducing overall system complexity.
Solution Approach 2:
Existing well components such as packers and hangers are designed to serve multiple functions: mechanical support, sealing, and electrical isolation. This multi-functionality reduces the need for additional dedicated isolation structures, thereby reducing overall system complexity.
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 solution enables efficient power and signal transmission with low ohmic losses, allowing for controlled hydrocarbon production and instrumentation in multiple zones, with the ability to replace sensitive equipment without comprehensive well interventions, achieving reliable data transmission and efficient energy transfer.
Implementation Method 1
a primary coil arranged concentrically about the production pipe, a secondary coil arranged concentrically about the production pipe... connected to the secondary coil... an alternating current generator/signal unit connected to the primary coil
Implementation Method 2
coils having ferromagnetic cores to enhance coupling
Data Source
Figure 1~2
Figure 3
AI summary
Well for production of hydrocarbons, comprising a hole drilled down into an underground, a casing fastened to the hole wall, a production pipe that extends into the casing from the surface and down to a hydrocarbon-containing zone, a hanger on the surface in an upper end of the well, in which hanger the production pipe and casing are hung up and electrically short-circuited, and a packer arranged sealingly and electrically short-circuiting in the annulus between the production pipe and the casing, in or close to a lower end of the well, distinguished in that the well further comprises: a primary coil arranged concentrically about the production pipe, a secondary coil arranged concentrically about the production pipe, a load connected to the secondary coil, and an alternating current generator/signal unit connected to the primary coil.