Managed Pressure Drilling System with Segmented BOP Pressure Control
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Solution Overview
Problem
Current managed pressure drilling (MPD) techniques face challenges in deep water drilling, including gas release issues, pressure fluctuations, and crossflow limitations, particularly in harsh environments with subsea BOP stacks, leading to inefficiencies and safety concerns.
Innovation Solution
The implementation of a system using a heavier mud circulation in the riser annulus and seawater injection down the drill pipe, combined with a dynamic pressure control method that adjusts surface back-pressure through a pressure control valve and booster line, enables safe and efficient gas handling and pressure management, even during connections and potential loss scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional MPD techniques with subsea BOP stack are used, then deep water drilling is enabled, but gas release occurs in low pressure riser causing safety risks and operational complexity
Solution Approach 1:
The system divides the wellbore into two separate pressure zones: a high-pressure zone below the BOP stack where gas is contained and controlled, and a low-pressure zone above the BOP stack where gas is safely discharged. The BOP stack acts as a barrier that segments the pressure regimes, allowing high-pressure drilling operations while maintaining safety in the surface equipment.
Solution Approach 2:
The BOP stack serves as an intermediary barrier between the high-pressure drilling environment and the low-pressure surface equipment. It mediates the pressure transition by containing high-pressure gas below while allowing controlled discharge above, protecting surface equipment from high-pressure conditions.
2Reliability
If heavier mud is circulated in riser annulus, then overbalanced pressure is maintained preventing gas influx, but system complexity increases
Solution Approach 1:
The circulation system performs multiple functions simultaneously: the heavier mud circulation provides overbalanced pressure control to prevent gas influx, while the same circulation system enables dynamic pressure adjustment through the BOP stack. This multi-functionality reduces the need for separate pressure control mechanisms.
Solution Approach 2:
The system dynamically changes the density parameter of the circulation fluid by using heavier mud in the riser annulus compared to the drill pipe. This parameter change enables the maintenance of overbalanced pressure conditions, preventing gas influx while allowing controlled drilling operations.
3Stability of the object's composition
If dynamic pressure control is applied during connections, then pressure fluctuations are reduced improving wellbore stability, but operational complexity increases
Solution Approach 1:
The system employs feedback control where the BOP stack position and pressure conditions are continuously monitored during connections. The dynamic pressure control adjusts the BOP stack position or opening size based on real-time pressure feedback, automatically compensating for surge and swab effects without requiring complex manual intervention.
Solution Approach 2:
The BOP stack system dynamically adjusts its opening size or position in response to changing wellbore pressure conditions during connections. This dynamic adjustment allows the system to adapt to surge and swab effects, maintaining pressure stability while simplifying the connection operations through automated response.
4Reliability
If crossflow prevention methods are used, then gas influx is reduced improving drilling safety, but drilling efficiency decreases
Solution Approach 1:
The system extracts and removes gas from the wellbore column by allowing it to rise through the BOP stack opening and discharge at the surface. This extraction method prevents gas influx into the drilling mud column while maintaining efficient drilling operations, as the gas is continuously removed rather than contained under pressure.
Solution Approach 2:
The system converts the potentially harmful effect of gas presence into a beneficial process by using the gas rise through the BOP stack as a natural gas removal mechanism. The gas that would otherwise cause influx problems is instead allowed to rise and discharge, effectively preventing crossflow and improving drilling efficiency simultaneously.
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 safer, more cost-effective, and time-efficient drilling by maintaining overbalanced pressure, reducing gas influx and crossflow risks, and stabilizing wellbore conditions, thereby enhancing drilling operations in challenging deep water environments.
Implementation Method 1
maintaining overbalanced pressure
Implementation Method 2
adjusts surface back-pressure through a pressure control valve
Implementation Method 3
seawater injection down the drill pipe
Data Source
AI summary
A method for managed pressure drilling comprising: extending a drilling riser with a drill string from a floating installation to a subsea blow-out preventer stack; providing a first fluid in the drilling riser annulus and a second fluid in a fluid conduit extending from the floating installation, where the first fluid has a higher density than the second fluid; circulating the second fluid through a control valve which is fluidly connected to the fluid conduit and operating the control valve to apply a surface back-pressure so as to obtain a pre-determined, desired combined hydrostatic and frictional circulation pressure below the subsea blow-out preventer stack.