Downhole Flow Metering System for ESP Water Cut
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Solution Overview
Problem
Current flow measurement technologies in hydrocarbon production, particularly when wells are producing below bubble point pressure, fail to provide accurate flow rates due to liberated gas, necessitating costly replacements of surface meters with multi-phase meters, and existing downhole solutions are not effective for wells with intake pressures above bubble point pressure.
Innovation Solution
A flow metering system comprising selectively disposed pipe sections with pressure sensors that measure gravitational and frictional losses, where the controller calculates a pressure gradient and flow rate using hydraulic equations, allowing for accurate flow rate measurement and water cut estimation, even in conditions where frictional losses are negligible, and is integrated with an electrical submersible pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If surface single phase meters are used to measure flow rate, then the measurement is simple and low cost, but the measurement accuracy deteriorates when wells produce below bubble point pressure due to liberated gas
Solution Approach 1:
The patent introduces an intermediary device - a downhole flow metering system with pressure sensors and calculation algorithms that acts as a mediator between the wellbore environment and surface measurement needs. This intermediary system measures pressure differentials downhole and calculates flow rate, avoiding the need for complex multi-phase meters at the surface while maintaining accuracy in gas-containing flows.
2Measurement precision
If multi-phase meters are installed at the surface to measure flow rate accurately when wells produce below bubble point pressure, then the measurement accuracy improves, but the cost increases by tens of thousands of dollars per well
Solution Approach 1:
The patent extracts the measurement function from the surface environment to the downhole environment. By placing pressure sensors inside the wellbore and performing calculations based on downhole pressure differentials, the system removes the need for expensive multi-phase meters at the surface, achieving accurate measurement at a fraction of the cost.
Solution Approach 2:
The patent creates a virtual representation of flow conditions through mathematical calculations based on pressure measurements. Instead of directly measuring complex multi-phase flow at the surface, the system copies the essential flow information through pressure differential measurements and computational algorithms, achieving accurate flow rate determination without expensive hardware.
3Measurement precision
If downhole flow measurement is implemented using the pressure differential method with pipe sections of different diameters, then the measurement accuracy improves for wells above bubble point pressure, but the device complexity increases
Solution Approach 1:
The patent divides the measurement system into distinct segments - an upper pipe section and a lower pipe section with different diameters, each with its own pressure sensors. This segmentation allows the system to create controlled flow conditions where gravitational losses dominate in one section and both gravitational and frictional losses occur in another, enabling accurate flow calculation through differential pressure measurements.
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 provides a low-cost, accurate method for extending the life of electrical submersible pumps by enabling precise flow rate monitoring and water cut calculation, reducing the need for costly meter replacements and improving operational efficiency.
Implementation Method 1
a first pressure sensor on the first pipe section that measures a first pressure loss of the flow of fluid along at least a portion of the first pipe section
Implementation Method 2
a controller in communication with the first and second pressure sensors and that calculates a pressure gradient along a portion of the second pipe section based on the equation PG=(g)(ρm)/((gc)(144))
Data Source
AI summary
An apparatus for metering fluid in a subterranean well includes an electric submersible pump having a motor, a seal section and a pump assembly and a metering assembly. The metering assembly includes an upper pipe section with an outer diameter, the upper pipe section having an upper pressure sensing means, and a lower pipe section with an outer diameter smaller than the outer diameter of the upper pipe section, the lower pipe section having a lower pressure sensing means. A power cable is in electronic communication with the electric submersible pump and with the metering assembly.