Pistonless Rotary Steerable System Steering Mechanism
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Solution Overview
Problem
Rotary steerable systems (RSS) face challenges in maximizing reliability and minimizing maintenance due to complex mechanical, electrical, and hydraulic elements, particularly the wear-down of pistons in push-the-bit systems, which require removal to the surface for repair, increasing drilling operation costs.
Innovation Solution
A pistonless RSS design that combines aspects of point-the-bit and push-the-bit systems, using a radially movable pusher arrangement controlled by a flexible drive shaft with an eccentric ring assembly to achieve steering responses, eliminating the need for wear-prone pistons and reducing mechanical stresses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If push-the-bit system with pistons is used, then steering response is achieved, but reliability decreases due to seal wear and piston failures
Solution Approach 1:
The patent removes the piston assembly and seals from the RSS system entirely, extracting the problematic components that caused wear and reliability issues. The steering function is achieved through a different mechanism (flexible drive shaft with偏心 ring) that does not require pistons, thereby eliminating seal wear and piston failures while maintaining the push-the-bit steering capability.
Solution Approach 2:
The patent replaces the hydraulic/mechanical piston system with a flexible drive shaft mechanism. Instead of using pistons that require seals and hydraulic fluid, the system uses a flexible drive shaft with an偏心 ring to achieve radial movement of the drive shaft, thereby substituting a simpler mechanical system that has fewer wear points and higher reliability.
2Ease of operation
If complex mechanical elements are used, then steering function is achieved, but maintenance needs increase
Solution Approach 1:
The patent extracts the complex piston assembly, seals, and hydraulic components from the system. By removing these maintenance-intensive elements, the system requires significantly less maintenance while preserving the essential push-the-bit steering function through the flexible drive shaft mechanism.
Solution Approach 2:
The patent discards the worn-prone piston and seal components that require frequent maintenance and recovery operations. The simplified flexible drive shaft system with偏心 ring is designed to be more durable and require less maintenance, allowing the system to operate longer between maintenance intervals and reducing overall maintenance needs.
3Reliability
If pistons with seals are used, then push-the-bit steering is achieved, but cost increases due to removal for repair
Solution Approach 1:
The patent removes the piston assembly that requires periodic removal for seal replacement and repair. By eliminating these components, the system avoids the time loss associated with retrieving the RSS to surface for maintenance, thereby maintaining continuous drilling operations and improving operational reliability.
Solution Approach 2:
The patent enables continuous drilling operations by eliminating components that would interrupt the drilling process for maintenance. The flexible drive shaft system is designed to operate continuously without the need for periodic shutdowns and retrievals required by piston-based systems, thereby maintaining uninterrupted useful action and reducing time loss.
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 design enhances the dog-leg capability of RSS, increases reliability, and reduces maintenance needs by avoiding piston-related failures, allowing for more efficient and cost-effective drilling operations in various wellbore configurations.
Implementation Method 1
A pistonless RSS design that combines aspects of point-the-bit and push-the-bit systems, using a radially movable pusher arrangement controlled by a flexible drive shaft with an eccentric ring assembly to achieve steering responses
Data Source
AI summary
An example apparatus for controlling the direction of drilling a borehole includes a housing and a radially offsetable drive shaft at least partially within the housing. The apparatus may further include one or more pusher extendable from the housing. The one or more pusher may be extendable in response to a radial offset in the offsetable drive shaft with respect to a longitudinal axis of the housing.