Bladder Control Valve for Natural Gas Wellbore Liquid Loading
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Solution Overview
Problem
Natural gas wells face challenges in maintaining optimal production due to liquid loading and friction loading, where liquid accumulation leads to increased bottomhole pressures and reduced gas recoveries, and existing control valves are expensive, complex, and vent gases to the atmosphere.
Innovation Solution
A system utilizing programmable logic controllers (PLCs) and bladder-type control valves with solenoids to regulate fluid flow and pressure, allowing for variable set points and minimizing gas venting, while determining optimal production modes and adjusting wellbore velocities to prevent liquid loading and friction loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional control valves are used to regulate fluid flow, then flow control function is achieved, but the valves are expensive, complex, and vent gases to the atmosphere
Solution Approach 1:
The patent extracts the atmospheric venting function from the control valve system by introducing a separate venturi device that creates a vacuum to operate the diaphragm, eliminating the need for atmospheric venting ports in the valve body itself. This separates the control function from the actuation mechanism, simplifying the overall valve design while maintaining functionality.
Solution Approach 2:
The patent introduces a diaphragm as an intermediary element between the process fluid and the control mechanism. The diaphragm translates pressure differential (created by the venturi vacuum) into valve opening/closing action, providing a simple mechanical linkage that eliminates complex internal valve components and atmospheric venting requirements.
2Ease of operation
If existing control valves are used, then flow regulation is achieved, but gas is vented to the atmosphere causing environmental concerns
Solution Approach 1:
The patent converts the potentially harmful atmospheric venting into a beneficial closed-loop system. The venturi device uses the flow of process gas itself to create the vacuum needed for actuation, and all gas movement occurs within closed pathways. This converts what would be harmful emissions into a self-contained system where gas is continuously circulated and controlled without atmospheric release.
3Loss of energy
If liquid accumulation is allowed in the wellbore, then production costs are reduced, but bottomhole pressures increase and gas recoveries decrease
Solution Approach 1:
The patent implements a feedback control system where the actual wellbore liquid level is continuously monitored and compared to the desired setpoint. The PLC controller automatically adjusts the control valve position based on this feedback to maintain optimal liquid levels, preventing both excessive liquid accumulation (which would increase costs) and overly aggressive liquid removal (which could reduce gas recovery). This closed-loop control optimizes the balance between cost and productivity.
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 system effectively optimizes natural gas production by preventing liquid accumulation, reducing friction loading, and minimizing gas venting, leading to increased production efficiency and cost-effectiveness.
Implementation Method 1
a venturi device adapted for operation with no atmospheric venting and having a vacuum source in fluid communication with a diaphragm
Implementation Method 2
The control valve assembly may include a solenoid in communication with the programmable logic controller and in communication with the control valve
Implementation Method 3
bladder-type control valves with solenoids to regulate fluid flow and pressure
Data Source
AI summary
In a system for optimizing natural gas production in response to real-time variations in wellbore parameters, a PLC or other wellsite intelligence technology is used to monitor liquid and gas production from the wellbore under friction-loaded conditions. Using baseline production data obtained during production tests, the PLC determines and initiates the appropriate operating mode for the wellbore to optimize a selected production criterion to suit measured wellbore parameters. The operating mode either a continuous clean-out mode, in which gas is continuously injected into the wellbore to control liquid loading, or an intermittent clean-out, in which liquid loading is regulated by intermittent gas injection. In preferred embodiments, the system uses bladder-type control valves having upstream and downstream solenoids, to control production tubing flow rate within a range between upper and lower set points.