Coriolis Flowmeter Diversion for High-Pressure Drilling
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Solution Overview
Problem
Current flow measurement technologies in drilling systems, such as managed pressure drilling (MPD), face challenges in accurately measuring flow rates across a full range due to limitations in measuring fluid density and inefficiencies in mud pumps, and are prone to errors from plugging and pressure changes, especially when using Coriolis flowmeters and differential pressure transducers.
Innovation Solution
A control manifold system with a differential pressure device, piping, and a processing unit that measures a diverted portion of the flow to correlate the main flow rate through the flowline, using a variety of differential pressure devices and flowmeters, including orifice plates, V-cones, and Coriolis flowmeters, to determine the main flow rate by accounting for fluid characteristics and pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Coriolis flowmeter is used to measure outflow, then density and flow rate measurements are obtained, but the flowmeter has pressure limitations and cannot be installed directly in high-pressure drilling applications
Solution Approach 1:
The system divides the flow measurement function into two parts: a differential pressure device (orifice plate, V-cone, or venturi) handles the high-pressure flow splitting, while a Coriolis flowmeter measures the diverted portion at lower pressure. This segmentation allows the Coriolis flowmeter to operate within its pressure limits while still measuring the main high-pressure flow indirectly.
Solution Approach 2:
A diverted portion of the flow acts as an intermediary between the main high-pressure flow and the Coriolis flowmeter. The differential pressure device creates this intermediate flow path that reduces pressure before the fluid enters the Coriolis flowmeter, enabling accurate measurement without exposing the flowmeter to excessive pressure.
2Stress or pressure
If drilling fluid flows through chokes to reduce pressure before measurement, then the Coriolis flowmeter can operate within pressure limits, but cavitation and gas flashing occur that prevent accurate flow rate measurement
Solution Approach 1:
The differential pressure device creates a controlled pressure reduction and flow diversion before the fluid reaches the Coriolis flowmeter. This preliminary action occurs upstream, allowing the main flow to be split in a controlled manner that avoids the cavitation and gas flashing problems that would occur if the entire flow went through a choke.
Solution Approach 2:
Instead of reducing the pressure of the entire flow through a choke, the system applies partial action by diverting only a portion of the flow through the differential pressure device. This partial diversion achieves the necessary pressure reduction for the Coriolis flowmeter while leaving the main flow intact and avoiding cavitation issues.
3Device complexity
If stroke counters are used to measure inflow, then pump stroke counting is simple, but the measurements are inaccurate due to inability to measure density and pump inefficiencies
Solution Approach 1:
The patent replaces the mechanical stroke counter system with a differential pressure-based measurement system combined with Coriolis flowmetry. This substitution eliminates the need to mechanically count strokes and manually calculate flow based on pump specifications, instead using direct physical measurements of pressure differential and fluid properties to determine flow rate accurately.
4Ease of operation
If density measurements are taken at atmospheric pressure, then measurements can be made easily, but the measurements cannot be done continuously and lack accuracy due to fluid property changes under pressure
Solution Approach 1:
The system extracts a diverted portion of the flow from the main high-pressure stream and routes it through the differential pressure device to the Coriolis flowmeter. This extracted sample allows density and flow rate measurements to be taken under controlled conditions that reflect the actual high-pressure fluid properties, providing both continuity and accuracy.
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 solution provides accurate and continuous measurement of main flow rates in drilling systems, reducing errors from plugging and pressure changes, and enabling real-time control by correlating diverted flow rates to main flow rates through defined relationships and fluid characteristics, enhancing the reliability of flow measurements.
Implementation Method 1
The differential pressure device is disposed in the flowline and produces a pressure drop in the flow from an upstream side of the differential pressure device to a downstream side of the differential pressure device
Implementation Method 2
a Coriolis flowmeter can measure both density and flow rate
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
In a drilling system for drilling a borehole with drilling fluid, a flow loop communicates the drilling fluid, and a differential pressure device in the flow loop at a measurement location produces a pressure drop in flow. The measurement location can be between the borehole and a drilling choke or between a mud pump and the borehole. Piping diverts a portion of the flow at the measurement location so a flowmeter can measure the diverted flow portion. A processing unit receives a measured parameter from the flowmeter and determines a diverted flow rate of the diverted portion therefrom to correlate it to a value of the main flow rate through the flow loop at the measurement location.