Rotary Steerable Tool Piston Shut-Off Valve for Mud Flow Control
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Solution Overview
Problem
Existing rotary steerable tools face challenges in achieving high build rates at higher drilling string rotational speeds, suffer from wear due to abrasive drilling mud, and lack reliable systems to control fluid flow to pistons, leading to inefficient steering control and premature tool failure.
Innovation Solution
A rotary steerable tool with a fluid control valve system featuring a spool and piston shut-off valve that allows controlled fluid flow to and from pistons, using a spool shaft with passages and a rotatable piston shut-off valve to manage fluid communication, enabling adjustable activation and deactivation phases and preventing unnecessary piston operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed-loop hydraulics system with pump, fluid control valves, and fluid reservoir is used to deploy pistons, then piston control capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the fluid reservoir and pump components from the closed-loop system, using only the drilling mud already circulating through the drill string. This reduces device complexity while maintaining piston control capability through a simplified open-loop system where mud is directed to pistons and then exhausted back to the wellbore.
Solution Approach 2:
The drilling mud serves multiple functions: it cools the drill bit, transports cuttings, and now also acts as the hydraulic fluid for piston actuation. This multi-functionality eliminates the need for a separate hydraulic system, reducing complexity while maintaining control capability.
2Power
If drilling mud is used to power pistons, then hydraulic power is readily available, but abrasive elements cause rapid wear
Solution Approach 1:
The patent segments the fluid flow path into separate channels: one for power delivery to pistons and another for exhaustion. By directing exhausted mud through a separate path that does not pass through the piston seals, the system minimizes the exposure of critical components to abrasive elements while maintaining power availability.
Solution Approach 2:
The patent introduces a shuttle valve as an intermediary component that controls the direction of mud flow. This allows the system to selectively connect pistons to either the power supply line or the exhaust line, enabling controlled exposure to abrasive elements only when necessary for actuation.
3Reliability
If particles are added to drilling mud to block rock formation holes, then wellbore stability is improved, but tool passages become blocked
Solution Approach 1:
The patent extracts and removes the fluid reservoir from the system, eliminating the enclosed passages where particles could accumulate and cause blockages. By exhausting mud directly to the wellbore rather than returning it to a reservoir, the system eliminates internal passages that could be blocked by lost circulation material.
Solution Approach 2:
The patent implements a dynamic shut-off valve system that can rapidly open and close fluid paths to pistons. This dynamic control allows the system to minimize the time that particles are exposed to piston chambers, reducing the opportunity for blockages while maintaining wellbore stability benefits.
4Ease of operation
If bleed nozzles are used to allow fluid escape from piston chamber, then piston return is achieved, but nozzles become blocked and energy is consumed
Solution Approach 1:
Instead of using small bleed nozzles to force fluid out against pressure, the patent inverts the approach by using a shut-off valve to control when fluid can escape. The system allows natural pressure equalization and piston return without forcing fluid through restricted passages, eliminating nozzle blockage risks and reducing energy consumption.
Solution Approach 2:
The patent uses a controlled shut-off valve that allows partial fluid escape during piston actuation rather than continuous escape through bleed nozzles. This partial action approach provides sufficient piston return control while minimizing the exposure of small passages to abrasive particles and reducing the energy required for piston cycling.
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
The system enhances drilling performance by maintaining high build rates, reducing piston wear, and providing flexible control over steering operations, ensuring reliable fluid flow management and tool longevity.
Implementation Method 1
The piston shut off valve can rotate to a first position relative to the spool shaft such that the shut off valve port at least partially overlaps with the spool inlet port to provide fluid communication between the first passage and the drilling fluid inlet port
Implementation Method 2
The piston shut off valve can rotate to a second position relative to the spool shaft such that the shut off valve port does not overlap with the spool inlet port and seals the first passage from fluid communication with the drilling fluid inlet port
Implementation Method 3
At least one spool inlet port in the spool shaft provides fluid communication between an outer surface of the spool shaft and the first passage
Implementation Method 4
a friction plate rotatably mounted on the spool shaft and fixedly connected to the inner chamber, wherein the friction plate is slidably coupled to the piston shut off valve
Data Source
Figure 1
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Figure 4
AI summary
A shut-off system and control method for a rotary steerable tool that includes a body having an inner chamber, a piston gallery extending between the inner chamber and a piston port, and an exhaust gallery extending between the inner chamber and an exhaust port. A spool in the inner chamber is movable into a plurality of positions to direct and control the flow of drilling fluid to energize pistons of the rotary steerable tool. The spool includes a spool shaft. A first passage extends through the spool shaft and receives drilling fluid via a spool inlet port in the shaft from a drilling fluid inlet port of the rotary steerable tool. A shut off valve is controlled to rotate on the spool shaft to open and shut the spool inlet port to drilling fluid flow.