Dynamic Annular Pressure Control for Drilling Well Kick Detection
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Solution Overview
Problem
Existing drilling methods using open-loop fluid circulation systems face challenges in detecting well control events, such as gas kicks, due to the time required to increase drilling fluid density and the resulting pressure spikes, which can lead to formation fluid influx and fracturing, especially in dynamic annular pressure control (DAPC) systems that lack a separate backpressure pump.
Innovation Solution
A method for determining well control events by pumping drilling fluid through a drill string into an annular space, selectively controlling the aperture of an orifice to maintain a selected fluid pressure, and monitoring changes in the orifice aperture and fluid flow rates to estimate and maintain bottom-hole pressure, thereby generating a warning signal for any deviations from a set threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drilling fluid density is increased to control formation fluid influx, then formation fluid entry is prevented, but pressure spikes occur that can fracture the formation
Solution Approach 1:
The system performs preliminary actions by continuously monitoring annular pressure and detecting deviations before they lead to formation fluid influx. The backpressure pump is activated in advance to adjust pressure, preventing the need for sudden density increases that would cause fracturing.
Solution Approach 2:
The system implements feedback control by continuously measuring annular pressure, comparing it to expected pressure levels, and adjusting the backpressure pump operation accordingly. This closed-loop control prevents pressure spikes while maintaining control of formation fluid influx.
2Speed
If drilling fluid density is increased rapidly to respond to gas kicks, then formation fluid influx is controlled, but formation fracturing occurs
Solution Approach 1:
The backpressure pump is pre-positioned and ready to adjust annular pressure immediately upon detecting a gas kick, eliminating the need for slow density increases. This preliminary preparation enables rapid response while avoiding the harmful effects of sudden pressure spikes.
Solution Approach 2:
The system uses hydraulic principles by employing a backpressure pump to control annular pressure directly, providing rapid and smooth pressure adjustment without the need for rapid density changes that would cause formation fracturing.
3Reliability
If a separate backpressure pump is added to DAPC systems, then well control events are detected and controlled more effectively, but device complexity increases
Solution Approach 1:
The backpressure pump is designed to serve multiple functions: maintaining annular pressure during normal operation, detecting well control events through pressure deviations, and controlling formation fluid influx. This multi-functionality justifies the added complexity by providing comprehensive control capabilities.
Solution Approach 2:
The backpressure pump integrates feedback control mechanisms that continuously monitor annular pressure and adjust operation accordingly. This feedback system enables effective detection and control of well control events, making the added complexity worthwhile for improved safety and reliability.
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 approach allows for early detection and control of well control events, reducing the risk of formation fluid influx and fracturing by maintaining stable annular pressure without relying on a separate backpressure pump, thus enhancing drilling safety and efficiency.
Implementation Method 1
The drilling fluid is also formulated such that the hydrostatic pressure applied by the drilling fluid is greater than surrounding formation fluid pressure, thereby preventing formation fluids from entering into the borehole.
Implementation Method 2
Annular space fluid pressure is selectively increased to maintain a selected fluid pressure proximate the bottom of the borehole by applying fluid pressure to the annular space.
Data Source
AI summary
A method for controlling formation pressure during drilling includes pumping a drilling fluid through a drill string in a borehole, out a drill bit at the end of the drill string into an annular space. The drilling fluid is discharged from the annular space proximate the Earth's surface. At least one of a flow rate of the drilling fluid into the borehole and a fluid flow rate out of the annular space is measured. Pressure of the fluid in the annular space proximate the Earth's surface and pressure of the fluid proximate the bottom of the borehole are measured. Pressure of the fluid proximate the bottom of the borehole is estimated using the measured flow rate, annular space pressure and density of the drilling fluid. A warning signal is generated if difference between the estimated pressure and measured pressure exceeds a selected threshold.