Oil Gas Production Feedback Control for Flow Rate Variations
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Solution Overview
Problem
Oil and gas production systems face challenges in maintaining throughput and regularity due to flow rate variations, which can lead to system overloading, instability, and inefficient ramp-up processes, particularly due to nonlinearities and interactions between controlled variables, and the lack of direct measurements for flow rates.
Innovation Solution
A method for automatic feedback control and monitoring that includes determining level or pressure indicators, calculating set points to mitigate flow rate variations, and compensating for nonlinearities using control modules, while avoiding system overload and optimizing ramp-up through modules like Outflow Smoothening, Overload Avoidance, and Ramp-Up, employing predictive control and PID algorithms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a tightly tuned level controller is used to maintain constant liquid level, then liquid level stability is improved, but flow rate variations are amplified and disturbances are not mitigated
Solution Approach 1:
The patent implements a feedback control system that uses level controller output signals as input to a feedback controller, which then adjusts the inlet valve opening to mitigate flow rate variations. This closed-loop feedback mechanism allows the system to respond to level changes while actively reducing flow rate disturbances, resolving the contradiction between maintaining level stability and reducing flow variations.
Solution Approach 2:
The patent dynamically adjusts controller parameters including level controller output, feedback controller output, and inlet valve opening based on real-time operating conditions. By changing these parameters adaptively rather than using fixed tight tuning, the system can maintain liquid level stability while simultaneously mitigating flow rate variations that would otherwise be amplified by aggressive control.
2Device complexity
If conventional PID controllers are used without compensation for nonlinearities, then device complexity is reduced, but control accuracy deteriorates under varying operating conditions
Solution Approach 1:
The patent compensates for nonlinearities by dynamically adjusting controller parameters such as proportional gain, integral time, and derivative time based on real-time measurements of liquid level, gas pressure, and flow rates. This adaptive parameter adjustment maintains high control accuracy across varying operating conditions without requiring a fundamentally more complex controller architecture.
Solution Approach 2:
The patent transforms the static PID controller into a dynamic system where controller parameters continuously adapt to changing operating conditions. The feedback controller dynamically modifies control actions based on real-time system state, enabling the simple PID structure to achieve high accuracy under varying conditions through dynamic parameter adjustment rather than fixed parameters.
3Stability of the object's composition
If buffer tanks are used to mitigate flow rate variations, then flow rate regularity is improved, but system throughput is reduced due to conservative control
Solution Approach 1:
The patent implements dynamic control that adapts buffer tank operation to real-time system conditions. The feedback controller dynamically adjusts inlet valve opening and control parameters based on measured flow rates, liquid levels, and gas pressures, allowing the buffer tank to mitigate flow rate variations while maximizing throughput by avoiding overly conservative control actions.
Solution Approach 2:
The patent changes controller parameters including inlet valve opening, level controller output, and feedback controller output based on real-time operating conditions. This dynamic parameter adjustment allows the system to use buffer tank capacity effectively for flow rate mitigation while maintaining higher throughput by adapting control aggressiveness to actual system needs rather than using fixed conservative settings.
4Quantity of substance
If flow rate measurements are not directly available, then measurement equipment cost is reduced, but control reliability deteriorates due to estimation uncertainty
Solution Approach 1:
The patent introduces a feedback controller as an intermediary that processes level controller output signals and generates control actions based on estimated system state. This intermediary layer allows the system to operate reliably without direct flow rate measurements by using available measurements (liquid level, gas pressure) and controller outputs to infer and respond to flow rate variations.
Solution Approach 2:
The patent implements a feedback control mechanism that uses available measurements (liquid level, gas pressure, inlet valve opening) to continuously adjust control actions. This feedback loop compensates for the lack of direct flow rate measurements by using the relationship between measured variables and controller outputs to maintain reliable control, reducing dependence on expensive direct flow measurement equipment.
Data Source
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AI summary
A method for automatic feedback control and/or monitoring of an oil and/or gas production system, or part(s) thereof, which includes one or more processing unit(s) and/or one or more flow line(s) and/or one or more controls. The method includes measuring or estimating value(s) of at least one level or pressure or flow rate or load indicator associated with at least one of the processing unit(s) and/or flow line(s) and at least one of calculating setting(s) for the controls based on at least one controlled variable in form of the measured or estimated level or pressure or flow rate or load indicator, including compensating for nonlinearities of the control means or estimating at least one of the oil-, gas-, water-, or liquid flow rate(s) into and/or out of at least one of the processing units and/or flow line(s).