Variable Throat Venturi Flow Meter for Downhole Tool Passage
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Solution Overview
Problem
Conventional Venturi flow meters struggle to accurately measure low flow rates in oil and gas wells due to insufficient pressure differential, and their small throat cross-sectional area prevents the passage of downhole tools, limiting their effectiveness in transient production periods and drill stem testing.
Innovation Solution
A variable throat Venturi flow meter that adjusts its throat cross-sectional area to accommodate downhole tools and varying flow rates, using rotatable inserts, revolving sleeves, or spring blades to alter the throat size for accurate flow rate measurements while allowing tool passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the throat cross-sectional area is made very small to increase pressure differential for accurate low flow rate measurement, then measurement precision is improved, but downhole tools cannot pass through the flow meter
Solution Approach 1:
The patent employs a variable throat area design where the throat cross-sectional area can be dynamically adjusted between a first state (smaller area for measurement) and a second state (larger area for tool passage). This is achieved through movable elements such as sliding sections, rotatable inserts, or expandable structures that change the effective throat area based on operational requirements, allowing the flow meter to adapt between measurement mode and tool access mode.
Solution Approach 2:
The invention changes the geometric parameter of the throat cross-sectional area from a fixed value to a variable value. By controlling the throat area parameter to switch between two distinct states, the system optimizes for either measurement precision or tool passage capability depending on the operational phase, effectively resolving the contradiction between these two requirements.
2Ease of operation
If the throat cross-sectional area is kept large to allow tool passage, then ease of operation is improved, but pressure differential becomes insufficient for accurate low flow rate measurement
Solution Approach 1:
The flow meter utilizes dynamic throat area adjustment mechanisms that allow the system to switch between a larger throat area configuration (enabling tool passage) and a smaller throat area configuration (enabling accurate measurement). The movable components such as sliding sections or rotatable inserts can be repositioned to create the appropriate throat geometry for the current operational need.
Solution Approach 2:
The invention implements variable control over the throat cross-sectional area parameter, allowing it to be changed between two states. When tool passage is required, the throat area is increased; when measurement is required, the throat area is decreased to maximize pressure differential and measurement accuracy.
3Measurement precision
If a fixed small throat area is used to measure low flow rates, then measurement precision is improved, but adaptability to varying flow rates and tool passage is reduced
Solution Approach 1:
The patent implements a dynamically adjustable throat area system that can adapt to different operational conditions. The movable elements (sliding sections, rotatable inserts, or expandable structures) allow the throat area to be changed based on the flow rate being measured or the need for tool passage, providing versatility while maintaining measurement precision when needed.
Solution Approach 2:
The flow meter is designed with multi-functionality, serving both as an accurate measurement device for low flow rates and as a passage way for downhole tools. The variable throat area mechanism enables the single device to perform multiple functions by adjusting its geometry, making it adaptable to various operational requirements including different flow rates and tool sizes.
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
Enables accurate measurement of low flow rates and accommodates downhole tools by dynamically adjusting the throat area, maintaining differential pressure and minimizing errors in flow rate determination, thus overcoming the limitations of conventional Venturi flow meters.
Implementation Method 1
the velocity of the fluid increases, which results in a corresponding decrease in pressure in the throat, according to the well known Bernoulli principle according to which the total energy in a steadily flowing fluid system is a constant along a flow path
Data Source
AI summary
A variable throat Venturi flow meter includes an upstream pipe section having an upstream cross-sectional area, a throat section having a variable throat cross-sectional area that is smaller than the upstream cross-sectional area, and a plurality of section-varying elements adapted to temporarily vary the throat cross-sectional area to allow a downhole tool to pass through the throat section.