Drill String Reactive Twist Compensation in Directional Sliding Drilling
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Solution Overview
Problem
Current sliding drilling methods face limitations in achieving accurate directional control and high penetration rates due to reactive twist of the drill string, low transmission bandwidth, and the need to toggle between sliding and rotary modes, which results in poor wellbore smoothness and reduced drilling efficiency.
Innovation Solution
A method that estimates the mud motor torque and reactive twist angle by measuring drilling fluid pressure, and uses a control loop to rotate the drill string in the opposite direction of the calculated twist, allowing for instant regulation of the tool face, combined with advanced hydrodynamic modeling and twist compensation to maintain a stable tool face and reduce wellbore curvature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sliding drilling is used with a steerable motor assembly, then directional control is provided at low cost, but the reactive twist of the drill string causes significant and undesired changes in tool face
Solution Approach 1:
The system continuously measures the tool face angle via MWD tools and compares it with the desired trajectory. A control loop adjusts the mud motor torque to compensate for reactive twist, creating a closed-loop feedback system that maintains tool face stability despite string twist dynamics.
Solution Approach 2:
The system dynamically adjusts the mud motor torque parameter based on real-time measurements of tool face angle and desired trajectory. By changing the torque parameter in response to measured twist, the system compensates for reactive twist effects and maintains accurate directional control.
2Manufacturing precision
If the drill string is not rotated but slid into the well, then directional control is provided, but the penetration rate is reduced compared to rotary drilling
Solution Approach 1:
The system enables dynamic control of the tool face angle during sliding drilling by continuously adjusting mud motor torque. This dynamic capability allows the bit to maintain optimal cutting conditions while following the desired trajectory, improving penetration rate without sacrificing directional control accuracy.
3Loss of information
If mud pulse telemetry is used for measurement transmission, then measurement data are transmitted to surface, but the low transmission bandwidth makes measurement rates relatively slow
Solution Approach 1:
The system performs preliminary calculations of reactive twist angle and required torque compensation based on measured tool face angle and desired trajectory. By pre-calculating compensation values, the system can respond more quickly to trajectory deviations despite the slow measurement rate, effectively compensating for the bandwidth limitation.
4Manufacturing precision
If the bit is powered and rotated by a mud motor, then directional control is provided, but high and variable axial wellbore friction makes it difficult to control bit load and bit torque
Solution Approach 1:
The system uses MWD measurements of tool face angle and desired trajectory to create a feedback loop that continuously adjusts mud motor torque. This feedback mechanism compensates for the effects of axial friction, enabling more precise control of bit load and torque despite variable wellbore friction conditions.
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 enhances directional control and penetration rates by stabilizing the tool face and reducing wellbore curvature, leading to improved drilling efficiency and smoother well trajectories without the need for frequent mode toggling.
Implementation Method 1
The bit is powered and rotated by a mud motor which can be either a positive displacement motor or a turbine motor driven by the drilling fluid pumped through the drill string
Implementation Method 2
a mud motor which can be either a positive displacement motor or a turbine motor driven by the drilling fluid pumped through the drill string
Implementation Method 3
A special challenge with sliding drilling is the reactive twist of the string arising from a typical bit torque. As an example, a 3000 m long section of standard 5-inch drill pipes exposed to a typical bit torque of 5 kNm is twisted about 2.4 turns
Implementation Method 4
rotating the drill string, by means of a drill string rotation means, an angle substantially equal to but in the opposite direction of the calculated reactive twist angle
Data Source
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AI summary
There are described methods for controlling the direction of a wellbore trajectory during directional sliding drilling by means of a drill string having a drill bit rotatable, by means of a mud motor, around a drill bit rotation axis at its lower end, the direction of the drill bit rotation axis defining a tool face, wherein one of the methods comprises the following steps: a2) obtaining data indicative of the torque of the mud motor; and b2) calculating a reactive twist angle of the drill string by multiplying the obtained torque from step a2) by the torsional drill string compliance, wherein the method further comprises the step of : c2) rotating the drill string, by means of a drill string rotation means, an angle substantially equal to but in the opposite direction of the calculated reactive twist angle. There are also described systems for executing the methods as well as computer program products comprising instructions for causing a processor to perform the methods as described herein.