Packer Sub Check Valve Annulus Depressurization
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Solution Overview
Problem
During oil and gas well drilling and completion, pressurized fluids in the annulus can cause well kicks and equipment damage when packers are removed, and existing technologies fail to prevent premature fluid escape from the work string into the annulus during circulation treatments.
Innovation Solution
A work string with a packer sub and check valve system that allows pressurized fluids from the annulus to enter the work string while preventing fluids from exiting the work string, using a sub body with a check valve that opens at a predetermined minimum pressure to control fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a packer is installed to seal the annulus, then hydraulic isolation of zones is achieved, but pressurized fluid accumulates underneath the packer causing well kick risk
Solution Approach 1:
A check valve is introduced as an intermediary component in the packer sub to control fluid flow direction. The check valve allows fluid to flow from the annulus into the work string while preventing reverse flow, thereby managing the pressurized fluid accumulation problem without compromising the packer's sealing function
Solution Approach 2:
The harmful pressurized fluid is extracted from the annulus by directing it through the check valve into the work string, which then transports the fluid to the surface. This removes the dangerous pressure buildup while maintaining the packer's isolation capability
2Ease of operation
If the packer is removed from the borehole, then work string retrieval is achieved, but sudden pressure drop causes blowout
Solution Approach 1:
The check valve performs preliminary action by continuously managing fluid pressure and flow direction during the work string's downhole operation. This preliminary control of pressurized fluid prevents the sudden pressure drop that would occur during retrieval, eliminating the blowout risk
Solution Approach 2:
The check valve converts the harmful pressurized fluid that could cause blowout into a controlled flow path through the work string. The previously dangerous high-pressure fluid is now safely transported to the surface through the work string, turning a hazard into a manageable flow
3Productivity
If circulation fluid is pumped through the work string, then treatment is achieved, but fluid may escape prematurely into the annulus
Solution Approach 1:
The check valve serves as an intermediary that enforces one-way flow control. It allows circulation fluid to pass through the packer sub into the annulus only after completing its intended path through the work string, preventing premature escape while maintaining treatment effectiveness
Solution Approach 2:
The check valve provides flow direction feedback by mechanically responding to pressure differentials. When circulation pressure exceeds a certain threshold, the check valve opens to allow fluid passage; otherwise, it remains closed to prevent premature escape, creating a self-regulating flow control 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
Prevents well kicks by safely depressurizing the annulus and ensures full depth circulation of fluids during treatments, maintaining safety and equipment integrity by controlling fluid direction and pressure.
Implementation Method 1
The check valve is operable to open upon exertion of a predetermined minimum pressure on the check valve by the fluid in the annulus
Data Source
AI summary
A work string locatable in a borehole so as to form an annulus around the work string and a method of depressurizing the annulus are provided. The work string includes a packer expandable radially out from the work string to seal the annulus and a packer sub positioned below the packer including a sub body and a check valve in the body and operable to permit fluid in the annulus to flow into the work string and prevent fluid in the work string from flowing into the annulus. The check valve is operable to open and permit fluid in the annulus to flow into the work string upon exertion of a predetermined minimum pressure on the check valve by the fluid in the annulus. The method includes providing the work string in the borehole and depressurizing the annulus by permitting fluid in the annulus to flow through the check valve.