Stratified Flow Multiphase Flowmeter with Phase Segregation
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Solution Overview
Problem
Current multiphase flow measurement techniques in hydrocarbon-bearing reservoirs face challenges such as inaccurate liquid holdup and velocity measurements due to micro gas bubbles and limited operational range, particularly in viscous liquids, and the separation of gas from liquid is affected by trapped bubbles, leading to erroneous results.
Innovation Solution
A flowmeter system that generates stratified flow by using an accumulator with an inflow orifice and an outflow orifice to separate phases, combined with ultrasonic measurements for liquid holdup and capacitance-based water holdup sensors to measure the flow rates of oil and water separately, ensuring accurate measurement of multiphase flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If swirl generator is used to separate gas from liquid, then phase separation is achieved, but micro gas bubbles remain trapped in liquid layer causing measurement errors
Solution Approach 1:
The flow measurement system is segmented into distinct measurement zones: one for gas phase (upper portion of pipe) and one for liquid phase (lower portion of pipe). This segmentation allows separate measurement of each phase without interference from microbubbles in the liquid layer, as the gas velocity is measured in the gas core where no liquid contamination exists.
Solution Approach 2:
The patent introduces an intermediary approach by using the gas core as a mediator to obtain gas velocity measurements. Instead of attempting to measure gas velocity directly through the liquid layer where microbubbles cause errors, the system uses the clean gas core region as an intermediary measurement zone that provides accurate gas velocity data.
2Measurement precision
If ultrasonic time-of-flight measurement is used, then liquid holdup can be measured, but accuracy is limited by unknown speed of sound in liquid phase
Solution Approach 1:
The patent replaces the traditional ultrasonic time-of-flight measurement method with a differential pressure-based measurement system. Instead of using ultrasound waves whose speed in the liquid is unknown, the system uses differential pressure measurements across a Venturi flowmeter, which can be accurately related to flow rate through established fluid mechanics relationships without requiring knowledge of the liquid's speed of sound.
3Adaptability or versatility
If swirl flowmeter is used to increase operational range, then higher liquid flow rates can be measured, but pressure drop increases significantly
Solution Approach 1:
The patent applies partial swirl generation rather than full swirl. The flow conditioner creates a moderate amount of swirl sufficient to maintain phase separation and enable measurement, but not excessive swirl that would create high pressure losses. This partial action approach achieves the minimum necessary swirl effect while minimizing energy loss.
Solution Approach 2:
The system changes the operational parameters by using differential pressure measurements and slip correlation methods that are valid across a wide range of flow conditions. By adjusting the measurement approach based on flow regime parameters rather than relying on strong swirl effects, the system achieves high turn-down ratio with acceptable pressure drops.
4Measurement precision
If Venturi-based differential pressure measurement is combined with nuclear phase fraction, then flow rates can be determined, but device complexity increases
Solution Approach 1:
The patent extracts and removes the nuclear measurement component from the system, replacing it with conventional differential pressure sensors and ultrasonic sensors. This extraction eliminates the complexity and safety concerns associated with nuclear sources while maintaining flow rate measurement capability through the differential pressure-based method combined with slip correlation.
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 effectively separates and measures the flow rates of gas, oil, and water, providing accurate and reliable data across a wider range of flow rates, reducing errors caused by micro gas bubbles and improving operational efficiency.
Implementation Method 1
separate out the phases, according to their densities
Implementation Method 2
Ultrasonic techniques may be used to measure the liquid fraction and velocity
Implementation Method 3
an apparatus is configured to generate stratified flow of multiphase fluid
Data Source
AI summary
A conditioning accumulator (2) for use in a multiphase flow measurement system. The conditioning accumulator includes a container which has an inflow orifice connected to the end of an inflow pipe and an outflow orifice connected to the end of an outflow vessel. The lowest point of the inflow orifice is positioned at or near the bottom of a sidewall of the container. The outflow orifice is positioned in a sidewall of the container, where the lowest point of the outflow orifice is vertically offset and above the lowest point of the inflow orifice when the container is in an operational orientation. The container includes a phase distributer located next to the inflow orifice adapted to distribute the liquid and gas phases of the incoming flow from the inflow pipe within the container. An exit flow resistance device reduces/resists the outflow of liquid from the container.