Preemptive Pressure Offset for Drilling Flow Diversion
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Solution Overview
Problem
Current well drilling technologies face challenges in precisely controlling wellbore pressure and flow during drilling operations, particularly in managing the pressure balance between pore pressure and fracture pressure, especially when the margin between them is small, and in maintaining controlled influx of fluids.
Innovation Solution
The system employs a rotating control device (RCD) to isolate and pressurize the annulus, using a hydraulics model and sensors to regulate pressure and flow through a choke manifold and bypass system, allowing for continuous pressure control even during drill string connections, with automated control systems to maintain setpoint pressure and flow distribution between the standpipe and bypass lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flow is diverted from the standpipe to the bypass line during drill string connections, then continuous pressure control is maintained, but pressure fluctuations occur in the annulus
Solution Approach 1:
The system preemptively adjusts the annulus pressure setpoint before flow diversion occurs by detecting the drill string connection status and calculating the expected pressure change. This preliminary adjustment compensates for the upcoming flow reduction, maintaining stable annulus pressure throughout the connection process.
Solution Approach 2:
The control system continuously monitors actual annulus pressure and compares it to the adjusted setpoint, dynamically modifying the setpoint based on real-time pressure measurements and predicted flow changes. This closed-loop feedback ensures pressure stability despite flow variations during connections.
2Ease of operation
If drilling operations are stopped for drill string connections, then drill string assembly can be completed, but fluid circulation must be interrupted
Solution Approach 1:
The fluid circulation system is segmented into two independent paths: the standpipe line for normal drilling circulation and the bypass line for connection operations. This allows flow to be redirected to the bypass line during connections, maintaining circulation without requiring drill string movement or stopping pumping operations.
Solution Approach 2:
The bypass line acts as an intermediary flow path that allows drilling fluid to circumvent the drill string during connections. Flow control valves regulate the distribution of fluid between the standpipe and bypass line, enabling continuous circulation while the drill string is being assembled.
3Adaptability or versatility
If the margin between pore pressure and fracture pressure is small, then drilling can proceed in challenging formations, but pressure control precision must be extremely high
Solution Approach 1:
The system calculates and applies a preemptive pressure offset to the annulus setpoint based on predicted flow changes, preventing pressure excursions before they occur. This proactive adjustment is particularly critical when the margin between pore and fracture pressure is small, as it eliminates the need for reactive pressure management that could exceed tight pressure limits.
Solution Approach 2:
The control system dynamically modifies the annulus pressure setpoint parameter based on flow conditions, drill string connection status, and formation pressure characteristics. By adjusting the setpoint offset in real-time, the system adapts to changing conditions while maintaining pressure within the narrow safe operating window.
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 enables precise control of wellbore pressure and flow, preventing fluid loss, fracturing, and influx, while allowing for continuous drilling operations without fluid circulation, thereby enhancing drilling efficiency and safety.
Implementation Method 1
a rotating control device (RCD, also known as a rotating control head, rotating blowout preventer, etc.) which seals about the drill pipe as the wellbore is being drilled
Implementation Method 2
using a hydraulics model and sensors to regulate pressure and flow through a choke manifold and bypass system
Data Source
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AI summary
A method of controlling pressure in a well can include transmitting an instruction to change flow through an annulus formed radially between a drill string and a wellbore, and adjusting a pressure setpoint in response to the transmitting. A well drilling system can include a flow control device which varies flow through a drill string, and a control system which changes a pressure setpoint in response to an instruction for the flow control device to change the flow through the drill string. A method of controlling pressure in a well can include transmitting an instruction to divert flow from a drill string, and adjusting a pressure setpoint in response to the transmitting.