Adaptive Stimulation System Resolving Pump Fatigue
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Solution Overview
Problem
Conventional frac pumps experience high failure rates due to vibration-induced fatigue caused by mechanical shocks from check valve closures, leading to fluid end failures, and existing stimulation methods lack efficiency in fracturing unconventional formations.
Innovation Solution
Adaptive stimulation systems employ swept-frequency vibration generated by tunable down-hole stimulators, combining cyclically varying hydraulic pressure with closed-loop control of power spectral density shifts to optimize stimulation efficiency and reduce resonance excitation, using backscatter vibration for real-time feedback and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical shocks from check valve closures are used to generate broad-spectrum vibration for stimulation, then stimulation coverage is improved, but vibration-induced fatigue and pump failure rate increase
Solution Approach 1:
The patent applies mechanical vibration by using a vibration isolation system with dampers and isolators to reduce the transmission of vibration-induced fatigue to pump components. This allows the system to maintain the beneficial broad-spectrum vibration for stimulation while protecting the pump from damaging resonance excitation, thereby resolving the contradiction between stimulation efficiency and pump reliability
Solution Approach 2:
The patent introduces vibration isolation components as intermediary elements between the mechanical shock source and the pump structure. These intermediaries (dampers, isolators) selectively filter out harmful vibration frequencies while allowing useful stimulation frequencies to pass through, thus protecting the pump without compromising stimulation effectiveness
2Device complexity
If fixed-frequency vibration is used for stimulation, then system simplicity is maintained, but resonance with geologic material cannot be optimized
Solution Approach 1:
The patent implements a swept-frequency vibration system that dynamically adjusts the vibration frequency over time to match the resonant frequencies of geologic material. This dynamic frequency adjustment allows the system to optimize stimulation efficiency by targeting specific rock resonances while maintaining relatively simple hardware through software-controlled frequency modulation
3Force
If high hydraulic pressure is applied continuously, then fracturing force is maximized, but energy loss and heat generation increase
Solution Approach 1:
The patent employs pulsed hydraulic pressure delivery combined with vibration cycles rather than continuous high-pressure application. This periodic action allows the geologic material to resonate and accumulate stress over multiple cycles, achieving effective fracturing with lower average pressure and reduced energy loss and heat generation
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 approach enhances frac pump reliability, increases well productivity, and optimizes stimulation efficiency by tailoring vibration frequency to resonate with geologic material, reducing unproductive energy transmission and minimizing heat loss.
Implementation Method 1
a hammer element is longitudinally movable within the housing between the driver element and the fluid interface, the hammer element being responsive to the driver element for striking the fluid interface and rebounding therefrom to generate broad-spectrum vibration
Implementation Method 2
transmitting, in response to a timed stimulator transmission signal, a vibration burst comprising a plurality of vibration frequencies having a power spectral density
Implementation Method 3
said fluid interface comprising at least one accelerometer for producing an accelerometer feedback signal representing vibration transmitted and received by said fluid interface
Implementation Method 4
each said adjustable power spectral density is responsive to one said adjustable rebound cycle time, and each said adjustable rebound cycle time is responsive to one said timed stimulator shift signal
Data Source
AI summary
Adaptive stimulation systems combine impulse-generated swept-frequency stimulation vibration with cyclically-varying hydraulic pressure to provide adaptive down-hole stimulation. Swept-frequency stimulation vibration arises from cyclical shifts of the power spectral density (PSD) of each stimulator's vibration (via closed-loop control of rebound cycle time). PSD's are adjusted for resonance excitation, fracturing and/or analysis of geologic materials at varying distances from a wellbore. And closed-loop control incorporates backscatter vibration from stimulated geologic material. Stimulators can be arranged singly or in spatial arrays of multiple stimulators, each stimulator generating vibration in bursts comprising a plurality of vibration frequencies. Timed signals from a programmable controller affect directional propagation of combined vibration wave fronts from a stimulator array. As fracturing proceeds to smaller (e.g., proppant-sized) fragments having higher resonant frequencies, PSD's are up-shifted, increasing relative stimulation vibration power in higher frequencies. Progressive stimulation is thereby optimized, facilitating plain-water (or liquefied propane) fracs with self-generated proppant.