Wellbore Fluid Level Monitoring via Bell Nipple Air Flow Sensing
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Solution Overview
Problem
During wellbore drilling, the loss of drilling fluid into loss circulation zones leads to challenges in monitoring the fluid level in the annulus, as existing methods fail to accurately detect fluid levels in real-time, affecting operational efficiency and safety.
Innovation Solution
A wellbore fluid level monitoring system that uses an air flow sensor installed in the bell nipple below the rotary table to measure air flow rates when the liquid level drops, allowing for computational determination of the fluid level through finite element modeling and a sealing mechanism to protect the sensor from liquids, enabling real-time fluid level detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an air flow sensor is installed in the annulus to detect fluid level, then real-time measurement capability is improved, but the sensor reliability deteriorates due to exposure to drilling fluid and harsh downhole conditions
Solution Approach 1:
A housing structure is introduced as an intermediary between the air flow sensor and the harsh annulus environment. The housing contains the sensor and allows it to function indirectly by detecting air flow changes in the annulus without direct exposure to drilling fluid, thus maintaining both measurement capability and sensor reliability
Solution Approach 2:
The system uses air flow as a proxy or copy of the actual drilling fluid condition. Instead of directly measuring drilling fluid level, the system measures air flow changes that occur when drilling fluid is lost, providing indirect but accurate fluid level information without exposing sensors to harsh conditions
2Reliability
If a sealing mechanism is added to protect the sensor, then sensor protection is improved, but device complexity increases
Solution Approach 1:
The housing structure is designed to be self-activating based on pressure differentials. When drilling fluid is lost and pressure changes occur, the housing automatically opens to allow air flow sensing, then closes to protect the sensor, eliminating the need for complex external control mechanisms
Solution Approach 2:
The housing combines multiple functions into a single structure: it serves as both the sensor mounting platform and the protective sealing mechanism. The pressure-responsive opening/closing feature integrates detection and protection functions, reducing overall system complexity
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 system allows for accurate and real-time monitoring of fluid levels in the annulus, enhancing operational efficiency and safety by preventing fluid loss and enabling effective mitigation strategies during loss circulation events.
Implementation Method 1
Air flowing in a downhole direction through a portion of an annulus within the bell nipple below the rotary table responsive to a decrease in a liquid level in the portion of the annulus is sensed
Implementation Method 2
The air sensor is sealed from the liquid responsive to determining that the portion of the annulus within the bell nipple is filled at least partially with the liquid
Data Source
AI summary
A wellbore fluid monitoring system can implement a method while drilling a wellbore using a drilling assembly that includes a drill string, a rotary table and a bell nipple below the rotary table. Air flowing in a downhole direction through a portion of an annulus within the bell nipple below the rotary table responsive to a decrease in a liquid level in the portion of the annulus is sensed. The annulus is formed by the drill string and an inner wall of the wellbore. In response to sensing the air flowing in the downhole direction, a flow rate of the air flowing in the downhole direction over a period of time is measured. Based on the flow rate and the period of time, a volume of air flowed in the downhole direction over the period of time is determined. A liquid level relative to the rotary table is determined based on the volume of air flowed in the downhole direction over the period of time.