Rotary Steerable Drilling System Geostationary Tool Face Control
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Solution Overview
Problem
Rotary steerable systems face challenges in maintaining a consistent target tool face during directional drilling, especially under varying downhole conditions and non-constant drill string rotation, due to unreliable power sources and susceptibility to stick slip conditions.
Innovation Solution
The system employs a two-stage planetary gearbox and differential gearing system to create a geostationary member that maintains the target tool face direction by reversing and adjusting the rotation of the driveshaft, using mechanical components and minimal electrical or hydraulic power, allowing for precise steering with limited feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If drilling fluid flow is used to counter rotate the geostationary portion of the RSS, then the geostationary portion can be maintained with net zero rotation, but the input flow rate is based on fluctuating drilling parameters and may not provide a consistent source of power
Solution Approach 1:
The system uses the rotational energy from the drill string itself to power the counter-rotation mechanism through the turbine and gear system, making the system self-powered without requiring external energy sources. The drill string rotation directly drives the turbine that generates the counter-rotating motion.
Solution Approach 2:
The patent replaces hydraulic or electrical power systems with a purely mechanical system using a turbine and gear train. The turbine converts the rotational energy of the drill string into mechanical work to drive the counter-rotation, eliminating the need for fluctuating hydraulic flow rates or electrical power sources.
2Reliability
If the rotating motion of the drill string is not constant during stick slip drilling conditions, then directional drilling becomes difficult, but the target tool face cannot be maintained
Solution Approach 1:
The system applies a counter-rotating force through the turbine and differential gear system to compensate for variations in drill string rotation. The counter-rotation acts as a stabilizing influence that maintains the target tool face orientation even when the drill string rotation speed varies during stick-slip conditions.
Solution Approach 2:
Instead of trying to control the drill string rotation directly, the system inverts the approach by allowing the drill string to rotate freely while generating an opposing counter-rotation through the turbine mechanism. This counter-rotation is used to stabilize the tool face orientation rather than controlling the primary rotation.
3Reliability
If a two-stage planetary gearbox and differential gearing system are used to create a geostationary member, then the target tool face direction can be maintained, but the device complexity increases
Solution Approach 1:
The turbine serves multiple functions: it extracts energy from the drill string rotation, generates counter-rotating motion, and provides a mechanical linkage to the differential gear system. The differential gear system simultaneously handles speed variation compensation and tool face orientation maintenance, making the system multi-functional despite its complexity.
Solution Approach 2:
The patent employs nested planetary gear systems where smaller planetary gear sets are contained within larger structural housings. The two-stage planetary gearbox is integrated within the overall RSS assembly, with components nested concentrically around the drill string to minimize spatial requirements while maintaining the complex gearing functionality.
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 provides a robust and energy-efficient mechanism for maintaining the target tool face direction, reducing susceptibility to changing downhole conditions and eliminating the need for constant electrical or hydraulic power, enhancing the reliability and precision of directional drilling.
Implementation Method 1
The system employs a two-stage planetary gearbox and differential gearing system to create a geostationary member that maintains the target tool face direction by reversing and adjusting the rotation of the driveshaft
Implementation Method 2
pivoting with a differential gearing system a rotatable tubular bit sleeve annularly arranged around a distal portion of the driveshaft by activating a first pressure applying device and/or a second pressure applying device connected respectively to a first eccentric cam and a second eccentric cam movably positioned concentrically around the driveshaft wherein pressure applied to each eccentric cam modifies a respective speed of rotation of each of the eccentric cams
Implementation Method 3
differential gearing system to create a geostationary member that maintains the target tool face direction by reversing and adjusting the rotation of the driveshaft
Data Source
AI summary
A rotary steerable drilling system includes a gear box driven by a driveshaft having an input rotatable in a first direction and an output rotatable in an opposite direction. An output of the gear box has a first axis of rotation, and a rotatable tubular bit sleeve annularly arranged around a distal portion of the driveshaft is pivotable to have a second axis of rotation and includes a connector assembly on a distal end of the bit sleeve for coupling the bit sleeve to a drill bit. A spherical CV joint couples the bit sleeve to the drive-shaft, eccentric cams are movably positioned on the driveshaft, a differential gearing system is connected to the eccentric cams, and a pressure applying device is connected to the eccentric cams. When activated, the pressure applying device applies pressure to modify the speed of rotation of the eccentric cams. A method of rotary steerable drilling is disclosed.