Managed Pressure Drilling Flow Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional managed pressure drilling systems face inaccuracies in fluid flow measurement, particularly when dealing with entrained gas, which can disrupt data and lead to potential kicks or loss of mud to the formation, due to the positioning of flow meters downstream of the choke, causing inaccuracies in bottom hole pressure control.
Innovation Solution
The system incorporates active sonar flow meters on both the inlet and annulus return lines, upstream of the choke, along with a Coriolis flow meter and a filter to prevent debris from blocking the Coriolis meter, ensuring accurate and reliable fluid flow measurement and back-pressure control, and includes pressure relief valves to manage excess pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow meters are positioned downstream of the choke to measure fluid flow, then flow measurement is possible, but measurement precision deteriorates due to entrained gas disrupting data
Solution Approach 1:
The patent positions the flow meter upstream of the choke device, performing the measurement action before the fluid undergoes pressure reduction and gas entrainment. This preliminary positioning ensures that measurements are taken when the fluid is in a stable, single-phase state, avoiding the data disruption caused by gas bubbles that occur downstream of the choke.
2Measurement precision
If a Coriolis flow meter is used to measure fluid flow, then measurement precision is improved, but device complexity increases due to susceptibility to debris blocking
Solution Approach 1:
The patent introduces a filter as an intermediary component positioned in the fluid return line between the annulus and the Coriolis flow meter. This filter captures debris and particulate matter before they can reach and block the sensitive Coriolis meter, enabling the use of this high-precision measurement device without the risk of debris-induced failures.
3Measurement precision
If back-pressure is applied to control bottom hole pressure, then bottom hole pressure control is improved, but formation fracturing risk increases due to excessive pressure
Solution Approach 1:
The patent implements a feedback control system where the Coriolis flow meter continuously measures the actual fluid flow rate returning from the annulus, and this measurement is fed back to the control mechanism adjusting the choke or back-pressure pump. This closed-loop feedback enables precise maintenance of bottom hole pressure within safe limits, preventing both under-pressurization (which could cause kicks) and over-pressurization (which could fracture the formation).
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 configuration provides direct, accurate, and reliable measurements of fluid flow, minimizing the risk of formation fracturing and mud loss, while maintaining precise control over bottom hole pressure, thus enhancing the safety and efficiency of the drilling process.
Implementation Method 1
an active sonar flow meter is provided to measure the rate of fluid flow along the inlet line
Implementation Method 2
a Coriolis flow meter which is downstream of the choke / valve
Data Source
AI summary
A drilling system including a drill string (12) which extends into a borehole (10), and a well closure system which contains fluid in the annular space (16) in the borehole around the drill string, the well closure system having a side bore whereby controlled flow of fluid out of the annular space in the borehole around the drill string is permitted, the side bore being connected to fluid return line (28) which extends from the side bore to a fluid reservoir (34), there being provided in the fluid return line a valve (30a) which is operable to restrict flow of fluid along the fluid return line to variable extent, and a flow meter (32) operable to measure the rate of flow of fluid along the fluid return line, the flow meter being located between the valve and the side bore, wherein a filter (40) is provided between the flow meter and the side bore, the filter including a plurality of apertures which have a smaller cross - sectional area than the smallest fluid flow lines in the flow meter.