Variable-Aperture Valve Orifices for Rotary Steering Pressure Control
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Solution Overview
Problem
Existing rotary directional drilling systems face challenges in maintaining optimal pressure drop across the drill bit, which affects the actuation force of steering pads, especially during changes in drilling conditions, such as transitioning from vertical to lateral wellbore formation, leading to inefficient hole cleaning and cuttings transport.
Innovation Solution
The implementation of a geostationary valve with variable-aperture orifices that can be dynamically adjusted to control the pressure drop across the drill bit, allowing for real-time optimization of the pressure differential without altering the annulus pressure, using a self-contained drive system powered by a downhole turbine and motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the drilling conditions change (e.g., transitioning from vertical to lateral wellbore), then the pressure drop across the drill bit becomes suboptimal, but adjusting the annulus pressure is complex and affects overall system stability
Solution Approach 1:
The system segments the pressure control function by introducing a separate geostationary valve assembly with variable aperture orifices that independently controls pressure drop across the drill bit. This segmentation allows localized pressure adjustment without requiring changes to the entire annulus pressure system, thereby improving pressure control while maintaining system stability.
Solution Approach 2:
The geostationary valve assembly acts as an intermediary device between the drilling fluid flow and the drill bit. By positioning the variable aperture orifices in this intermediate location, the system can modulate pressure drop locally before the fluid reaches the bit, providing fine-grained pressure control without directly manipulating annulus pressure.
2Force
If the pressure drop across the drill bit is increased to improve steering pad actuation force, then the actuation force improves, but the hole cleaning and cuttings transport efficiency deteriorates
Solution Approach 1:
The system implements dynamic control of the variable aperture orifices in the geostationary valve, allowing real-time adjustment of the pressure drop across the drill bit. This dynamic capability enables the system to optimize the balance between steering pad actuation force and hole cleaning efficiency based on current drilling conditions, rather than being constrained by fixed pressure settings.
Solution Approach 2:
The system changes the flow area parameter of the orifices in the geostationary valve to dynamically control pressure distribution. By adjusting the aperture size, the system can modify the pressure drop across the drill bit to achieve optimal steering force while maintaining sufficient flow velocity for effective hole cleaning and cuttings transport.
3Device complexity
If a fixed aperture valve is used to control pressure drop, then the device complexity is reduced, but the adaptability to varying drilling conditions deteriorates
Solution Approach 1:
The geostationary valve incorporates variable aperture orifices that can dynamically change their flow area in response to different drilling conditions. This dynamic characteristic allows the valve to adapt to varying pressure requirements during drilling operations, whether transitioning between vertical and lateral sections or responding to changes in rock hardness or flow rate.
Data Source
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AI summary
The disclosed embodiments relate to a rotary steering having a plurality of hydraulically actuated steering pad assemblies and a valve positioned between a primary flow channel of the rotary steering tool and an actuating piston of each of the plurality of steering pad assemblies. The representative valve includes a two-disk valve, with an uphole disk having a single, fixed-area aperture and a downhole disk having a plurality of independently variable-area orifices. Each of the independently variable valve orifices corresponds to one of a plurality of valve ports. In turn, each valve port being is fluidly coupled to, and operable to actuate, a corresponding piston of one of the plurality of steering pad assemblies. The independently variable-area orifices can be manipulated (gradually opened or closed) to vary the pressure drop across the tool, and thereby vary the magnitude of hydraulic force available to actuate the steering pad assemblies.