Pump-Curve Water Cut Determination for Oil and Gas Fluids
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Solution Overview
Problem
Conventional methods for determining water cut in oil and gas operations are inaccurate, require frequent calibration and maintenance, and involve costly and hazardous equipment, especially in high water cut or high gas-to-oil ratio wells.
Innovation Solution
A system and method utilizing a degassing vessel, centrifugal pump, and transmitters to measure pump suction and discharge pressures, flow rate, and temperature, coupled with a central processing unit to calculate water cut based on pump curves and specific gravity equations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional water cut flow meters are used, then water cut measurement is provided, but frequent calibration and maintenance are required
Solution Approach 1:
The patent replaces conventional mechanical water cut flow meters with a calculation-based system using pump performance curves. The system measures standard parameters (flow rate, suction pressure, discharge pressure, temperature) and calculates water cut through pump head and specific gravity equations, eliminating mechanical measurement components that require frequent calibration and maintenance
2Measurement precision
If conventional monitoring equipment is used, then water cut measurement is achieved, but costly monitoring for corrosion and safety is required
Solution Approach 1:
The patent employs standard, readily available instrumentation (pressure transmitters, flow transmitters, temperature transmitters) instead of expensive specialized water cut measurement equipment. These conventional sensors are less costly and do not require the same level of corrosion monitoring and safety infrastructure as dedicated water cut flow meters
3Measurement precision
If conventional water cut flow meters are used, then water cut measurement is provided, but large operation space is required
Solution Approach 1:
The patent integrates water cut measurement functionality into the existing pump system by utilizing standard sensors already present on the liquid outlet line. The calculation is performed through a computer processing unit that receives data from existing pressure, flow, and temperature transmitters, eliminating the need for separate measurement equipment and associated space
4Productivity
If conventional measurement methods are used, then flow rate measurement is provided, but accuracy is poor in high water cut or high gas to oil ratio wells
Solution Approach 1:
The patent changes the measurement approach from direct water cut flow metering to calculating water cut based on pump performance parameters. By measuring flow rate, suction pressure, discharge pressure, and temperature, the system determines pump head and specific gravity, which are then used to calculate water cut. This parameter-based calculation method maintains accuracy across varying well conditions including high water cut and high gas to oil ratio scenarios
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
Provides accurate and reliable determination of water cut, reducing operational costs and equipment complexity while improving measurement precision.
Implementation Method 1
a pump, fluidly connected to the degassing vessel via the liquid outlet line
Implementation Method 2
a pump suction pressure transmitter disposed on the liquid outlet line configured to measure a pump suction pressure, a pump discharge pressure transmitter disposed on the liquid outlet line configured to measure a pump discharge pressure
Implementation Method 3
a flow transmitter disposed on the liquid outlet line configured to measure a flow rate
Implementation Method 4
a temperature transmitter disposed on the liquid outlet line configured to measure a temperature
Implementation Method 5
determine a specific gravity of the fluid sample by Equation 1, and determine a water cut of the fluid sample by Equations 2 and 3
Data Source
AI summary
Processes, systems, and methods for determining water cut of a fluid sample in an oil and gas process facility including obtaining the fluid sample in a degassing vessel, measuring a pump suction pressure, a pump discharge pressure, a flow rate, and a temperature of the fluid sample, and obtaining a pump curve corresponding to the pump, the pump curve showing a relationship between the flow rate and a pump head. Processes, systems, and methods for determining water cut also include receiving the pump suction pressure, the pump discharge pressure, the flow rate, and the temperature, determining the pump head corresponding to the flow rate, determining a specific gravity of the fluid sample by Equation 1, and determining a water cut of the fluid sample by Equations 2 and 3, using a computer processing unit.