Multiphase Flow Rate Determination Using Pump and Conduit Pressure Differentials
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Solution Overview
Problem
Existing methods for determining flow rates of multiphase fluids in rotodynamic pumps, particularly in the oil and gas industry, face inaccuracies due to unknown mixture density, leading to unreliable operation and potential mechanical failures, and conventional multiphase flow meters are expensive and complex with limited ability to detect rapid changes.
Innovation Solution
A method that combines first and second pressure differentials and rotational speed measurements to determine the flow rate of multiphase fluids, allowing for continuous and accurate flow rate monitoring, even in the absence of a dedicated multiphase flow meter, and adjusts pump speed to maintain the flow within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional multiphase flow meters (e.g., VXTM system) are used to determine flow rates, then flow rate measurement capability is provided, but device complexity and cost increase significantly
Solution Approach 1:
The flow rate determination is divided into two separate measurement components: a first pressure differential measurement across the pump and a second pressure differential measurement across a flow meter positioned in series with the pump. By segmenting the measurement into these two simpler components rather than using a single complex multiphase flow meter, the system achieves flow rate determination capability while reducing overall device complexity and cost.
Solution Approach 2:
The system uses standard single-phase pressure-based flow meters and pump differential pressure measurements, which are conventional and well-established technologies. By making these existing components work together in a combined measurement approach, the system achieves multiphase flow rate determination without requiring specialized complex multiphase metering equipment.
2Measurement precision
If conventional multiphase flow meters are used, then flow rate data is obtained, but reliability and availability decrease compared to standard single-phase meters
Solution Approach 1:
The system employs standard single-phase pressure-based flow meters and pump differential pressure sensors, which are conventional and highly reliable technologies. By making these proven components work together in a combined measurement approach, the system achieves multiphase flow rate determination while maintaining the high reliability and availability characteristics of standard single-phase metering equipment.
3Measurement precision
If multiphase flow meters with 30-60 second sampling time are used, then flow rate is measured, but ability to detect rapid changes in fluid densities is reduced
Solution Approach 1:
The system continuously monitors both the pump differential pressure and the flow meter differential pressure, maintaining ready-to-use measurements that can immediately reflect changes in fluid properties. This continuous monitoring approach allows the system to detect rapid changes in fluid densities and composition much faster than conventional multiphase meters, enabling real-time detection of gas/liquid slugs and other rapid transitions.
4Measurement precision
If historical data is used for multiphase flow rate calculations, then flow rate can be estimated, but accuracy decreases due to variations in actual watercut or GOR
Solution Approach 1:
The system continuously measures actual pump differential pressure and actual flow meter differential pressure, using these real-time measurements to calculate the current multiphase flow rate. This feedback-based approach using actual measured data rather than historical estimates allows the system to accurately reflect current operating conditions, including variations in watercut and gas oil ratio, thereby significantly improving the reliability and accuracy of flow rate determination.
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 provides continuous, accurate, and reliable flow rate determination over extended periods, enhancing pump operation safety and reducing the risk of mechanical failure while being more cost-effective and capable of detecting rapid changes in fluid densities.
Implementation Method 1
measuring a first pressure differential of the multiphase fluid flowing through a rotodynamic pump operating at a rotational speed thereby driving the multiphase fluid
Implementation Method 2
combining the first and second pressure differentials and the rotational speed of the rotodynamic pump and determining therefrom a flow rate of the multiphase fluid
Data Source
AI summary
A method for determining flow rate of a multiphase fluid. The method includes measuring a first pressure differential (316) of the multiphase fluid flowing through a rotodynamic pump (310) operating at a rotational speed thereby driving the multiphase fluid, measuring a second pressure differential (326) of the multiphase fluid flowing through a portion (320) of a fluid conduit positioned in series with said rotodynamic pump, and determining, based on the first and second pressure differentials and the rotational speed of said rotodynamic pump, a flow rate of the multiphase fluid.