Proportional Control Chokes for Drilling Mud Flow Regulation
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Solution Overview
Problem
Mechanical mud pumps often operate at high minimum output force, leading to excessive drill mud flow rates, which can cause issues when heavier mud is required to balance the well or achieve target drill mud pressure, potentially fracturing the formation or damaging the borehole, especially when the hydrostatic pressure is near the fracture gradient.
Innovation Solution
The use of a plurality of control chokes downstream of the mud pumps to proportionally control the flow rate, allowing for lower flow rates to be achieved while maintaining constant pump rate, thereby reducing the pressure exerted on the wellbore and preventing formation damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical mud pumps operate at high minimum output force, then the pump can deliver sufficient flow rate to balance the well, but the flow rate becomes excessive and may fracture the formation or damage the borehole
Solution Approach 1:
A flow control device is introduced as an intermediary component between the mechanical mud pump and the wellbore. This device mediates the flow rate, allowing the pump to operate at its efficient high minimum output while the intermediary restricts and regulates the actual flow entering the wellbore to prevent formation fracturing.
Solution Approach 2:
The flow control device incorporates adjustable opening positions that allow dynamic regulation of the flow rate. The device can be adjusted to different openings to match varying drilling conditions, enabling the system to adapt between maintaining well balance and preventing formation damage by controlling the mud flow rate dynamically.
2Stress or pressure
If the hydrostatic pressure is near the fracture gradient, then the well can be balanced with lighter mud, but the formation may be fractured or borehole damaged due to minimum stroke rate being too high
Solution Approach 1:
The flow control device serves as a protective intermediary that decouples the pump's minimum stroke rate from the actual flow rate entering the formation. This allows the system to maintain hydrostatic pressure near the fracture gradient for well balance while the intermediary restricts flow to levels that preserve formation integrity.
3Reliability
If mechanical pumps with high minimum output force are used, then the drilling rig can maintain well balance, but the drill rig cannot effectively drill a borehole with optimum integrity
Solution Approach 1:
The flow control device acts as a precision intermediary that enables the crude mechanical pump system to achieve precise flow rate control. This intermediary component allows the drilling rig to maintain well balance reliability while simultaneously achieving borehole integrity by regulating flow to optimal levels.
Solution Approach 2:
The system changes the flow rate parameter from the pump's fixed minimum output to a regulated, adjustable flow rate through the control device. This parameter transformation allows the system to maintain well balance while optimizing borehole integrity by adjusting flow rate to match formation characteristics.
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 solution enables the drilling rig to maintain optimal integrity by controlling the drilling mud flow rate, reducing the risk of formation fracturing and improving the drilling process by keeping the bottom-hole pressure below the fracture gradient, thus enhancing the drilling efficiency and safety.
Implementation Method 1
The use of a plurality of control chokes downstream of the mud pumps to proportionally control the flow rate, allowing for lower flow rates to be achieved while maintaining constant pump rate, thereby reducing the pressure exerted on the wellbore
Data Source
AI summary
A system includes a mud pump for pumping a drilling mud from a drilling mud source, through a drill string, out a drill bit and into an annular, and a plurality of chokes disposed down stream from the mud pump, including a first choke disposed between the mud pump and the drill string, and a second choke disposed between the mud pump and a mud tank. The system further includes a fluid discharge conduit in fluid communication with the annular space for transferring the drilling mud to handling equipment in fluid communication with the mud tank. The first choke receives the drilling mud from the mud pump at a first flow rate, the first choke reduces drilling mud flow rate to a second flow rate less than the first flow rate, and the second choke reduces drilling mud flow rate to a third flow rate.