Cable Pack-Off Apparatus Seals Wellbore Void After Cable Removal
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Solution Overview
Problem
The upstream oil and gas industry faces challenges with 'parted tubing' in wells, where the production tubing separates due to defects, leading to the loss of power cables and other transmission lines, resulting in a void at the well head that can cause leaks of petroleum products, water, and gases.
Innovation Solution
A cable pack-off apparatus is designed to threadedly connect to the tubing head's auxiliary port, featuring a self-sealing mechanism with elastomeric packing elements and spring-loaded sealing balls that maintain a seal when the power cable and other lines are pulled out, preventing leaks and ensuring a secure wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the power cable and transmission lines are pulled out of the well head, then the well head can be accessed for maintenance or replacement, but a void is created that allows leaks of petroleum products, water, and gases
Solution Approach 1:
The seal assembly is pre-installed in the auxiliary port with sealing balls positioned in passages. When the cable is removed, the springs automatically push the sealing balls into the cable passage to seal the void, preventing leaks without requiring additional manual intervention.
Solution Approach 2:
The self-sealing mechanism uses spring-loaded sealing balls that automatically respond to cable removal. The springs provide the force to push the sealing balls into sealing positions, creating a self-actuating system that seals the port autonomously when the cable is pulled out.
2Object-affected harmful factors
If a seal is maintained in the auxiliary port, then fluid and gas leaks are prevented, but the port cannot be accessed when cables need to be removed or replaced
Solution Approach 1:
The seal assembly transitions from an open state during cable installation/removal to a sealed state when the cable is removed. The spring-loaded sealing balls dynamically adjust their position based on the presence or absence of the cable, providing both accessibility and sealing functionality at different times.
Solution Approach 2:
The sealing mechanism is pre-positioned in the auxiliary port, ready to seal automatically when the cable is removed. This preliminary positioning of sealing components ensures that the seal engages immediately upon cable removal without requiring additional steps.
3Reliability
If multiple sealing components are added to prevent leaks, then sealing reliability improves, but the device complexity increases
Solution Approach 1:
The sealing function is distributed to multiple sealing balls, each positioned in its own passage. This local distribution of sealing elements provides redundant sealing capability and ensures reliable sealing without requiring a single complex sealing mechanism.
Solution Approach 2:
The spring-loaded sealing balls use the spring force to automatically position themselves for sealing, eliminating the need for complex actuating mechanisms. The self-actuating nature of the springs reduces overall system complexity while maintaining high sealing reliability.
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 apparatus effectively seals the wellbore when power cables are removed, preventing the escape of fluids and gases, thus maintaining well integrity and ensuring safe operation even after tubing parting incidents.
Implementation Method 1
an elastomeric packing element configured to seal the power cable and transmission lines
Implementation Method 2
spring-loaded sealing balls that maintain a seal when the power cable and other lines are pulled out
Data Source
AI summary
A cable pack-off apparatus for a wellbore is provided. The apparatus is designed to threadedly connect to the auxiliary port of a tubing head, over the wellbore, and to receive a power cable. The power cable provides power to an ESP downhole. The cable pack-off apparatus provides a self-sealing mechanism in the event that the power cable must be pulled (or becomes pulled) from the wellbore, such as in the event of parted tubing. A packing element sealingly receives the power cable within a housing of the apparatus. A method for self-sealing a tubing head over a wellbore is also provided herein.