Rotary Steerable Drill Bit Orientation Control
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Solution Overview
Problem
Rotary steerable drilling systems face challenges in maintaining desired borehole direction and dogleg performance due to reactive torque and non-rotating drill strings, leading to increased drilling costs and reduced fluid production efficiency.
Innovation Solution
A rotary steerable system with a drive coupling featuring a flexible joint and tubular sleeve, equipped with evenly spaced actuators that apply pivoting forces to control the orientation of the drill bit, allowing for controllable orientation of the drill bit axis relative to the drill string while rotating, thereby maintaining steering direction without relying on constant angular orientation between the wellbore and system components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a mud motor with bent housing is used to drill directional wellbore, then the drill bit can be driven without rotating the drill string, but the reactive torque causes toolface to gradually change and the borehole deviates from desired azimuth
Solution Approach 1:
The system transitions from a static bent housing configuration to a dynamic active steering system where the drill bit axis can be continuously adjusted during drilling. The active steering mechanism applies controlled forces to maintain the desired toolface orientation despite reactive torque, enabling real-time correction of borehole trajectory to achieve precise azimuth control.
Solution Approach 2:
The system incorporates orientation devices and control mechanisms that continuously monitor the toolface angle and borehole trajectory. This feedback enables real-time detection of deviations caused by reactive torque and allows the active steering system to make corrective adjustments, maintaining the desired azimuth precision throughout the drilling process.
2Manufacturing precision
If the drill string is kept non-rotating to maintain toolface orientation, then the bend angle can steer the bit on a curve, but frictional drag increases and control over weight on bit is reduced
Solution Approach 1:
The system enables the drill string to rotate while the active steering mechanism dynamically maintains the desired toolface orientation. This dynamic approach eliminates the frictional drag associated with non-rotating drill strings and improves weight on bit control, while the active steering system continuously adjusts the bit axis to maintain precise orientation control throughout the drilling process.
Solution Approach 2:
The system replaces the passive mechanical steering approach (relying on fixed bend angle and non-rotating drill string) with an active steering mechanism that uses controlled forces to maintain toolface orientation. This substitution allows the drill string to rotate freely while the active system compensates for orientation changes, improving both productivity and control.
3Manufacturing precision
If the drill string is non-rotating, then the bend section can orbit around the borehole axis, but the drill string is more likely to get stuck in permeable zones with mud cake buildup
Solution Approach 1:
The system allows the drill string to rotate continuously while the active steering mechanism dynamically maintains the desired borehole inclination and azimuth. This eliminates the risk of drill string sticking in permeable zones, as the rotating drill string prevents mud cake buildup. The active steering system ensures that inclination control is maintained through real-time adjustments rather than relying on orbital motion of a non-rotating string.
4Adaptability or versatility
If actuators are spaced equally apart (e.g., 120° for three actuators), then the system has symmetric actuation capability, but the gate window must be large enough to activate at least two actuators simultaneously
Solution Approach 1:
The system activates at least two actuators simultaneously within the gate window, providing excessive actuation capability that ensures precise steering control. This partial activation of multiple actuators creates a redundant force system that can rapidly achieve the desired steering direction without requiring sequential actuator engagement, thereby reducing activation time while maintaining full adaptability.
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 precise control over the drill bit axis, reducing the risk of borehole deviation and improving drilling efficiency by allowing continuous orientation of the drill bit in the desired direction, thus minimizing excessive drilling costs and enhancing fluid production efficiency.
Implementation Method 1
a flexible joint connecting the first section to the second section for transmitting drilling loads therebetween and permitting pivoting of the second section relative to the first section
Implementation Method 2
Each of the actuators is adapted for applying a pivoting force to an inner surface of the tubular sleeve when activated
Implementation Method 3
A gate is provided for delivering a force-transmitting medium to activate the actuators when the actuators are moved through a wellbore-referenced window by rotation of the drive coupling's first section with the drill string
Data Source
AI summary
A rotary steerable system (“RSS”) includes a drive coupling having a first section adapted for connection within a drill string and a second section adapted for supporting a drill bit. A flexible joint connects the first section to the second section for transmitting drilling loads, such as torque and weight, therebetween and permitting pivoting of the second relative to the first section. A tubular sleeve is disposed about the flexible joint and at least portions of the first section and the second section. The tubular sleeve is connected to the second section for movement therewith and is sized to permit pivoting movement of the tubular sleeve relative to the portion of the first section disposed therein. At least three actuators are carried by the portion of the drive coupling's first section that is disposed within the tubular sleeve for applying a pivoting force to an inner surface of the tubular sleeve when activated.