Check Valve High Shut-In Pressure Well Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wells with high shut-in pressures, injecting treatment fluids such as water, scale inhibitors, or acid stimulation chemicals downhole is challenging due to the need for pressures exceeding maximum allowable injection pressures, posing risks and inefficiencies.
Innovation Solution
A method and system involving a check valve positioned downhole in the production tubing string, which is calibrated to open and allow fluid flow when the differential pressure exceeds a specified opening pressure, achieved by initially reducing wellhead pressure by bleeding off gas and increasing hydrostatic pressure with water, enabling treatment fluid injection at a lower pressure than the shut-in pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If treatment fluid is injected at high pressure to overcome shut-in pressure, then fluid injection is achieved, but maximum allowable injection pressure is exceeded causing safety risks
Solution Approach 1:
Gas is bled from the production tubing string before treatment fluid injection to reduce the shut-in pressure. This preliminary pressure reduction creates a pressure differential that allows treatment fluid to be injected at lower pressures while still achieving the required downhole injection pressure when combined with the hydrostatic head of the fluid column.
Solution Approach 2:
The density of the fluid column is changed by injecting treatment fluid that has a higher density than the original well fluids. This increases the hydrostatic pressure gradient, allowing the same downhole pressure to be achieved with a lower surface injection pressure, thereby maintaining safety while achieving injection objectives.
2Stress or pressure
If gas is bled from production tubing to reduce pressure, then injection pressure is reduced, but wellhead pressure decreases too much
Solution Approach 1:
The density of the fluid column is increased by replacing lighter well fluids with denser treatment fluid. This parameter change in fluid density compensates for the pressure reduction caused by gas bleeding, maintaining the necessary pressure differential for injection while using the reduced surface pressure.
Solution Approach 2:
The system utilizes the hydrostatic pressure generated by the fluid column itself (hydraulic pressure) rather than relying solely on surface injection pressure. By optimizing the fluid column density and height, the system achieves the required downhole pressure with lower surface injection pressure, allowing gas to be bled without compromising injection capability.
3Measurement precision
If check valve is calibrated to open at high differential pressure, then fluid flow control is precise, but injection pressure requirements increase
Solution Approach 1:
The density of the treatment fluid is increased relative to the original well fluids. This changes the hydrostatic pressure gradient in the tubing, allowing the check valve to open at a lower differential pressure while still achieving the required downhole injection pressure through the enhanced hydrostatic head of the denser fluid column.
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 approach lowers the required injection pressure, maximizing efficiency and safety while minimizing risk and complexity, allowing treatment fluids to be injected without exceeding maximum allowable pressures, thus optimizing well operations.
Implementation Method 1
the check valve operable to prevent fluid from flowing in an uphole direction through the production tubing string and to open to allow fluid in a downhole direction when a differential pressure across the check valve exceeds a specified opening differential pressure
Implementation Method 2
A specified volume of gas is flowed from the production tubing string above the check valve, thereby decreasing the pressure within the production tubing string at the wellhead from the first wellhead pressure to a second wellhead pressure less than the first wellhead pressure
Implementation Method 3
A hydrostatic pressure within the production tubing string at the check valve is increased by flowing a specified volume of water into the production tubing string above the check valve to at least partially replace the specified volume of gas
Data Source
AI summary
The check valve positioned within a production tubing string is configured to open when a differential pressure across the check valve exceeds a specified opening differential pressure. With the check valve closed, a specified volume of gas is flowed from the production tubing string, thereby decreasing the pressure within the production tubing string from a first wellhead pressure to a second, lesser wellhead pressure. Hydrostatic pressure within the production tubing string at the check valve is increased by flowing a specified volume of water into the production tubing string above the check valve to at least partially replace the specified volume of gas. After flowing the water, a specified volume of treatment fluid is injected into the production tubing string at an injection pressure less than the first wellhead pressure and greater than the second wellhead pressure, thereby opening the check valve and flowing the treatment fluid downhole.