Auxiliary Underdrive Pumping for Slow-Speed High-Pressure Fracturing
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Solution Overview
Problem
Existing fracking equipment is incapable of delivering frac fluid at a slow speed and high pressure during the preliminary fracturing stage due to mechanical limitations of power units and transmissions, which restrict flow rates and pressures.
Innovation Solution
An auxiliary underdrive system is integrated into the pressure pumper power unit, allowing the transmission to be driven at slower speeds than the engine's idle speed, facilitating different fracturing modes by providing power through a hydrostatic transmission path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high speed mixing is used to achieve homogeneous fluid distribution, then mixing efficiency is improved, but fluid pressure is lost
Solution Approach 1:
The system dynamically adjusts mixing intensity based on fluid viscosity and desired output characteristics. Variable speed motors allow the mixing mechanism to operate at optimal speeds that maintain pressure while achieving adequate homogeneity, rather than always using high speed mixing.
Solution Approach 2:
The patent replaces traditional high-speed mechanical mixing with alternative mechanisms such as progressive cavity pumps or helical elements that provide gentle mixing action. These mechanisms achieve fluid homogeneity through progressive displacement and gentle agitation rather than high-speed turbulence, thereby preserving fluid pressure.
2Stress or pressure
If high pressure is maintained throughout the system, then fluid delivery capability is improved, but fluid mixing becomes inadequate
Solution Approach 1:
The system divides the fluid handling process into separate stages: mixing occurs in dedicated mixing chambers or inline mixers where pressure is temporarily reduced or controlled, followed by high-pressure delivery through pumping systems. This segmentation allows each function to operate under optimal conditions without compromising the other.
Solution Approach 2:
The patent introduces intermediary mixing devices such as static mixers, dynamic mixers, or progressive cavity mixers that can achieve fluid homogeneity under pressure conditions. These intermediaries facilitate mixing without requiring complete pressure release, bridging the gap between pressure maintenance and mixing effectiveness.
3Device complexity
If standard speed pumping is used, then system simplicity is maintained, but fracturing fluid output at slow speed and high pressure cannot be achieved
Solution Approach 1:
The system utilizes progressive cavity pumps that fundamentally change the pumping mechanism from centrifugal (standard) to positive displacement. This parameter change in pumping technology enables the system to deliver fluid at variable speeds while maintaining high pressure, achieving slow speed high pressure output without requiring complex multi-pump systems.
Solution Approach 2:
The progressive cavity pump serves multiple functions: it acts as both a mixing element and a pumping element, and can deliver fluid across a wide range of speeds and pressures. This multi-functionality reduces overall system complexity by eliminating the need for separate mixing systems and standard speed pumps, achieving versatile performance with a single integrated device.
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
Enables the delivery of frac fluid at a slow speed and high pressure during the preliminary fracturing stage, followed by high speed and high pressure in the main fracturing stage, enhancing the effectiveness of hydraulic fracturing operations.
Implementation Method 1
The fracturing fluid is delivered to the wellbore through a progressive cavity pump that outputs slow speed and high pressure fracturing fluid
Data Source
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AI summary
An oilfield pressure pumping system is configured to perform a preliminary' fracturing stage or operation at a high pressure but slow speed before initiating normal fracturing. The oilfield pressure pumping system includes an auxiliary underdrive system that can drive the transmission at a slower input speed that can be provided by an idle speed of the power unit's engine to facilitate different fracturing modes, including a preliminary fracturing mode during a slow speed / high pressure preliminary fracturing stage. The auxiliary underdrive system may include a hydrostatic transmission driven by the engine and which, drives the transmission at an underdrive speed that would correspond to a sub-idle engine speed driving the transmission.