MPD Back Pressure System for Pump Failure
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Solution Overview
Problem
Managed pressure drilling (MPD) operations face challenges in maintaining constant back pressure during mud pump failure or loss of power, which can lead to borehole instability and collapse, as fully automated chokes alone may not be sufficient to prevent wellbore failure.
Innovation Solution
A system and method that maintains constant bottom hole and well bore pressure profiles by using a pressurized housing with a nitrogen high pressure bottle rack to recover and recharge mud, installed upstream of MPD chokes, to stabilize pressure in the event of power loss or mud pump failure, allowing time to restore power or activate a diesel-powered cement unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If fully automated MPD chokes are used to trap residual pressure during mud pump failure, then response time is reduced, but pressure control sufficiency deteriorates
Solution Approach 1:
The patent combines automated MPD chokes with a backup pressure maintenance system consisting of a pressure vessel, nitrogen gas supply, and manual choke control. This merging of automated and manual systems ensures that when pump failure occurs, the automated chokes provide immediate response while the backup system maintains sufficient pressure control over an extended period.
Solution Approach 2:
The pressure vessel is pre-filled with drilling fluid and the nitrogen gas supply is pre-prepared before pump failure occurs. This preliminary action ensures that when failure happens, the backup system can immediately begin maintaining pressure without delay, and the manual choke is already positioned for optimal pressure control.
2Device complexity
If MPD chokes alone are used to maintain bottom hole pressure, then system complexity is reduced, but wellbore stability deteriorates
Solution Approach 1:
The pressure vessel acts as a cushion or backup pressure source that is prepared in advance. When pump failure occurs, this pre-positioned pressure source immediately compensates for the loss, preventing wellbore instability without requiring complex real-time control systems.
Solution Approach 2:
The nitrogen gas in the pressure vessel serves as an intermediary that transfers pressure to the drilling fluid, which then maintains bottom hole pressure. This intermediary mechanism provides simple yet effective pressure maintenance without requiring direct mechanical connection or complex control systems.
3Stability of the object's composition
If constant well bore pressure profile is maintained during pump failure, then borehole stability is improved, but duration of pressure maintenance deteriorates
Solution Approach 1:
The system changes the pressure source from electrically-powered pumps to nitrogen gas pressure. This parameter change allows pressure maintenance to continue as long as the nitrogen supply lasts, extending the duration of pressure maintenance beyond what a single pump failure would allow while maintaining the constant pressure profile needed for borehole stability.
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
The system effectively maintains wellbore stability by maintaining constant pressure for a temporary period, preventing unstable formations from collapsing and providing time to address the power or pump failure issues, thereby reducing the risk of well loss.
Implementation Method 1
pressurized housing with a nitrogen high pressure bottle rack to recover and recharge mud
Data Source
AI summary
This system maintains bottom hole pressure and constant well bore pressure profile for a period of time in event of loss of power to rig pumps, rig pump failure or other loss of pressure to the primary flowline. The back pressure system diverts mud into the primary flowline to maintain pressure. The system provides time to get the diesel powered cement unit on line to maintain pressure or get the power reinstated to the rig pumps. The mud discharged into the primary flowline can be recovered back into the housing via the housing inlet line and the housing can be recharged via the N2 high pressure bottle rack. The back pressure system installs upstream of the MPD chokes with interfaces to the primary flow line to divert the drilling mud to the primary flowline.