Variable Displacement Pump for Downhole Power Management
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Solution Overview
Problem
Existing rotary steerable drilling systems face limitations in efficiently controlling bit deflection and maintaining constant power output across varying mud flow rates, leading to restricted drilling parameters and potential tool damage.
Innovation Solution
A dynamically variable displacement axial piston pump and a hinge joint that limits bit articulation to a single degree of freedom, allowing for spatially phased coherent symmetrical bidirectional deflections, enabling precise control of bit deflection and power management independent of mud flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed positive displacement pump is used to generate hydraulic power, then the pump structure is simple, but it works only over a very narrow range of mud flow rates and restricts the ability to optimize drilling parameters
Solution Approach 1:
The patent applies a variable displacement pump mechanism that dynamically adjusts its displacement based on mud flow rate conditions. The pump incorporates a control system with sensors that detect mud flow rate and automatically modify pump displacement to maintain optimal operation across varying flow conditions, thereby resolving the contradiction between adaptability and structural complexity.
Solution Approach 2:
The invention changes the operational parameters of the pump by implementing variable displacement capability. The pump can adjust its displacement parameter in response to changing mud flow rates, allowing it to operate efficiently across a wide range of flow conditions rather than being restricted to a narrow operating range, thus improving adaptability without excessive complexity.
2Power
If a mud turbine driving an electrical alternator is used to generate electric power, then power can be generated for bit actuation, but the system complexity increases and power control is less precise
Solution Approach 1:
The patent extracts the power generation function from the complex mud turbine-alternator system and implements a simpler hydraulic power generation approach using the variable displacement pump. This extraction eliminates the need for electrical alternators and associated electrical systems, reducing overall system complexity while maintaining precise power control through hydraulic actuation.
Solution Approach 2:
The invention transitions from an electrical power generation system (mud turbine driving alternator) to a hydraulic power generation system using the variable displacement pump. This hydraulic approach provides more precise power control through direct hydraulic actuation of the bit, while simultaneously reducing system complexity by eliminating electrical components and associated control systems.
3Ease of operation
If a universal joint with 2 or more degrees of freedom is used to connect shafts, then articulation flexibility is improved, but the mechanical complexity and spatial coordination requirements increase
Solution Approach 1:
The patent employs an asymmetric single-degree-of-freedom hinge joint design that provides sufficient articulation flexibility for the specific drilling application. Rather than using a symmetric universal joint with multiple degrees of freedom, the asymmetric hinge design simplifies the mechanism while maintaining the necessary operational flexibility for bit articulation during directional drilling.
Solution Approach 2:
The invention extracts only the essential degree of freedom needed for bit articulation from the complex universal joint system. By removing unnecessary degrees of freedom and associated mechanical complexity, the single-degree-of-freedom hinge joint provides adequate articulation flexibility for the drilling application while significantly simplifying the overall joint mechanism.
4Measurement precision
If the amplitude of bit deflections is controlled by adjusting pump displacement, then steering precision is improved, but the control system complexity increases
Solution Approach 1:
The patent implements a self-regulating control system where the variable displacement pump automatically adjusts its displacement based on feedback from sensors monitoring bit deflection and mud flow rate. This self-service control mechanism achieves precise bit deflection control without requiring complex external control systems, as the pump autonomously responds to changing conditions to maintain optimal steering precision.
Solution Approach 2:
The invention incorporates a feedback control mechanism where sensors detect bit deflection amplitude and mud flow rate conditions, and this information feeds back to the variable displacement pump control system. The pump automatically adjusts its displacement in response to this feedback, achieving precise steering control through a relatively simple closed-loop system that leverages the inherent controllability of the variable displacement mechanism.
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 directional drilling with reduced mechanical complexity, improved drilling efficiency, and increased power control, allowing for faster drilling and higher efficiency in curved sections by dynamically adjusting bit deflection and power output.
Implementation Method 1
a mud turbine powered dynamically variable displacement axial piston pump
Implementation Method 2
a mud turbine powered dynamically variable displacement axial piston pump
Data Source
AI summary
A dynamically controllable variable displacement axial piston pump is described. In an embodiment, the pump comprises a rotating cylinder with hydraulic pistons that contact the face of a swash plate. The angle of the swash plate can be controlled to thereby control the movement of the pistons, the displacement of the pump, and the power generated by the pump. The dynamically controllable variable displacement axial piston pump may be used in combination with a rotary steerable apparatus, including such an apparatus as described herein that uses hydraulic pistons to actuate the deflection of the bit, or in combination with other downhole tools and devices. When used down hole in a drill string with a drilling mud powered turbine, the dynamically controllable variable displacement pump limits and regulates the power provided to the tool over a wide range of drilling mud weights and flow rates.