Plunger Lift Slug Controller Intra-Cycle Pressure Management
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Solution Overview
Problem
Plunger lift systems face challenges in controlling liquid load during shut-in time, leading to potential stalling or excessive rising speed of the plunger, which can result in well liquid loading and equipment damage.
Innovation Solution
Intra-cycle control method that adjusts the size of the liquid slug by opening a control valve for short periods to maintain a manageable liquid slug size, monitored by pressure differential between casing and tubing pressures, allowing dynamic adjustments within the plunger cycle to prevent stalling and ensure safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the liquid slug size is not controlled during shut-in time, then the plunger can accumulate sufficient liquid load for lifting, but the plunger may stall or rise too fast causing equipment damage
Solution Approach 1:
The controller continuously monitors the pressure differential between casing and tubing during shut-in time and uses this feedback to dynamically adjust the control valve opening/closing cycles. When the pressure differential indicates excessive liquid accumulation, the controller opens the control valve to vent tubing pressure and reduce liquid slug size. This closed-loop feedback mechanism prevents both stalling (insufficient liquid) and excessive rising speed (too much liquid), ensuring reliable continuous plunger cycling.
Solution Approach 2:
The system transitions from static, predetermined valve timing to dynamic, real-time adjustment of control valve operation. The controller modifies the opening and closing cycles of the control valve based on instantaneous pressure differential measurements, allowing the liquid slug size to be dynamically controlled during shut-in time. This dynamic adaptation enables the system to respond to changing well conditions and maintain optimal plunger cycling across varying production scenarios.
2Device complexity
If simple timer-cycle control is used, then the device complexity is reduced, but the system cannot dynamically adjust to prevent liquid loading or plunger stalling
Solution Approach 1:
The patent replaces simple mechanical timer-cycle control with an electronic control system that uses pressure sensors and a microprocessor controller. The controller electronically monitors pressure differential and automatically adjusts valve timing based on real-time well conditions. This substitution of mechanical timing with electronic sensing and control provides adaptability while maintaining relatively simple device architecture through the use of standard sensors and microcontroller technology.
3Reliability
If the control valve is opened frequently during shut-in, then the liquid slug size is reduced preventing stalling, but the casing-tubing pressure buildup is interrupted reducing lift efficiency
Solution Approach 1:
The controller applies partial action by opening the control valve only for brief intervals during shut-in time, rather than maintaining continuous opening. These short-duration valve openings are sufficient to vent excess tubing pressure and control liquid slug size without significantly interrupting the overall pressure buildup process. The controller carefully times these partial openings to achieve the minimum necessary intervention for reliable plunger cycling while preserving gas pressure buildup efficiency.
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 method ensures continuous plunger cycling, preventing liquid loading and reducing the risk of equipment damage by maintaining an optimal liquid slug size, allowing for adjustments during the current cycle rather than relying solely on next cycle adjustments.
Implementation Method 1
gas pressure buildup in the casing-tubing annulus and surrounding reservoir to push a plunger, and a column of fluid ahead of the plunger, up the well tubing to the surface
Implementation Method 2
The plunger serves as a piston between the liquid and the gas, which minimizes liquid fallback
Implementation Method 3
the plunger falls through gas and liquid and then rests on a bumper spring at the bottom of the well
Implementation Method 4
surface measurements that show casing pressure being higher than tubing pressure during the shut in period
Data Source
AI summary
A method for controlling the liquid load size of a plunger lift well during the shut in time of the well to facilitate a controlled plunger rise. Intra-cycle control allows dynamic adjustments within a cycle to keep the plunger running and not stalling out or rising too fast. The method includes the steps of shutting in the well to build up pressure within the well, adjusting a size of a liquid slug within the tubing while the well is shut in, opening a valve to relieve pressure within the well and raise the plunger within the tubing, pushing the liquid slug out of the well with the plunger, and closing the valve wherein the plunger falls within the tubing. The intra-cycle adjustments include reducing the size of the liquid slug for preventing fluid loading and increasing the size of the liquid slug for controlling a rise rate of the plunger.