Downhole Acoustic Stimulation Tool Using Plasma Shockwaves
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Solution Overview
Problem
Existing acoustic stimulation tools for hydrocarbon or water wells have limitations in energy efficiency and frequency range, often requiring high energy per pulse and unable to achieve high discharge frequencies, leading to suboptimal acoustic treatment of formations.
Innovation Solution
A downhole acoustic stimulation tool with a sealed chamber, electrodes, and capacitors that induce cavitation and plasma formation, using a combination of ultrasonic energy and electrical pulses to create a shockwave, allowing for efficient energy conversion and high-frequency acoustic treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional electrohydraulic tools generate high-energy shockwaves, then acoustic treatment effectiveness is improved, but energy consumption per pulse increases and discharge frequency is limited
Solution Approach 1:
The tool employs periodic action by using capacitors that are repeatedly charged and discharged in rapid succession. The capacitor charging circuit charges capacitors during intervals between shockwave generation, and the discharge circuit rapidly discharges them to generate multiple shockwaves per second, enabling high discharge frequency while maintaining high shockwave energy through the periodic charge-discharge cycle
Solution Approach 2:
The tool changes parameters by varying the charge and discharge characteristics of the capacitors. By controlling the charging voltage, discharge timing, and capacitor capacitance values, the system optimizes both the energy content of each shockwave and the frequency at which shockwaves are generated, resolving the contradiction between power and productivity
2Loss of energy
If transducers are used to convert electrical energy directly to acoustic energy, then acoustic energy generation is efficient, but frequency range is limited to narrow bands
Solution Approach 1:
The tool uses phase transitions in water to generate acoustic energy. Electrical discharge causes rapid heating and vaporization of water, creating plasma and shockwaves that naturally contain broadband frequency content. This phase transition mechanism provides both high energy conversion efficiency and wide frequency range, eliminating the limitations of transducer-based narrowband systems
Solution Approach 2:
The tool replaces the mechanical transducer system with an electrohydraulic system based on electrical discharge and phase transition. This substitution eliminates the inherent frequency limitations of mechanical transducers while maintaining energy conversion efficiency through the direct conversion of electrical energy to thermal and acoustic energy via plasma formation
3Power
If high voltage pulses are applied to create plasma, then shockwave energy increases, but electrical energy consumption increases
Solution Approach 1:
The tool applies preliminary action by pre-charging capacitors during intervals when shockwave generation is not required. The capacitor charging circuit accumulates electrical energy in advance, so that when discharge is needed, the energy is already stored and can be released rapidly without requiring continuous high power input, thereby reducing overall electrical energy consumption while maintaining high shockwave energy
Solution Approach 2:
The tool ensures continuity of useful action by maintaining a continuous cycle of capacitor charging and discharging. The charging circuit operates continuously to keep capacitors charged, and the discharge circuit rapidly releases the stored energy to generate shockwaves back-to-back, ensuring continuous acoustic treatment without idle periods or energy waste
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 tool enables frequent plasma events, generating high-energy shockwaves with reduced electrical demand, enhancing formation permeability and resource release, and facilitating sonochemical reactions, improving resource recovery efficiency.
Implementation Method 1
at least one transducer arranged to generate an acoustic field between the electrodes thereby inducing cavitation in a volume of the liquid between the electrodes
Implementation Method 2
the electrical discharge has sufficient energy to induce a localized phase transition, in which a volume of the liquid between the electrodes is briefly vaporized and ionized so as to form a plasma
Implementation Method 3
This creates a shockwave in the liquid, which propagates outwardly into the formation
Implementation Method 4
at least one transducer arranged to generate an acoustic field between the electrodes thereby inducing cavitation in a volume of the liquid between the electrodes
Data Source
AI summary
A downhole acoustic stimulation tool comprises: a sealed chamber containing a liquid; a pair of electrodes located in the chamber; at least one transducer arranged to generate an acoustic field between the electrodes thereby inducing cavitation in a volume of the liquid between the electrodes; and at least one capacitor configured to apply a pulse voltage across the electrodes when discharged, thereby causing the cavitating volume of liquid to form a plasma which collapses to form a shockwave. The at least one transducer constitutes a first energy source, and the at least one capacitor back and electrodes constitute a second energy source. Alternative forms and arrangements of the first and second energy sources are also disclosed.