Characterisation and evaluation of shockwave generation in water conditions for coal fracturing

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389021%3A_____%2F19%3A00509654" target="_blank" >RIV/61389021:_____/19:00509654 - isvavai.cz</a>

Výsledek na webu

<a href="https://www.sciencedirect.com/science/article/abs/pii/S1875510019300988?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/abs/pii/S1875510019300988?via%3Dihub</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.jngse.2019.04.005" target="_blank" >10.1016/j.jngse.2019.04.005</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Characterisation and evaluation of shockwave generation in water conditions for coal fracturing

Popis výsledku v původním jazyce

We investigated the effect of circuit parameters on shockwaves generated by electrohydraulic discharge (EHD), and the application of EHD to stimulation of coal seam gas reservoirs. The discharge circuit analyses indicate that the deposited electrical energy used for shockwave generation is not simply determined by charging voltage or capacitance. The discharge efficiency is also affected by mutual interactions among inductance, resistance and capacitance as well as real-time current change. Furthermore, the relation between charging voltage and peak pressure strength revealed that voltage at breakdown point, ranging from 9 kV to 28 kV, was more closely associated to shock strength rather than the initial charge voltage. Generally, a higher breakdown voltage tends to lead to a stronger shockwave. Finally the EHD fracturing stimulation conducted on coal cubes showed the coal was effectively fractured with enormous cracks and voids. By using three-dimension computed-tomography (CT), the fracture extension and propagation in the coals are found to be obvious and extensive. Though the existing fracture greatly affects the new fracture development in vertical direction, the horizontal fractures parallel with the bedding plane direction are more likely to occur and even expand across the entire tested coal core. The dramatic coal permeability improvement (over a hundred times) after EHD also validates the cutting-through fractures, as does the enhancement of pore and porosity observed by morphology and structural characterisation via scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP).

Název v anglickém jazyce

Characterisation and evaluation of shockwave generation in water conditions for coal fracturing

Popis výsledku anglicky

We investigated the effect of circuit parameters on shockwaves generated by electrohydraulic discharge (EHD), and the application of EHD to stimulation of coal seam gas reservoirs. The discharge circuit analyses indicate that the deposited electrical energy used for shockwave generation is not simply determined by charging voltage or capacitance. The discharge efficiency is also affected by mutual interactions among inductance, resistance and capacitance as well as real-time current change. Furthermore, the relation between charging voltage and peak pressure strength revealed that voltage at breakdown point, ranging from 9 kV to 28 kV, was more closely associated to shock strength rather than the initial charge voltage. Generally, a higher breakdown voltage tends to lead to a stronger shockwave. Finally the EHD fracturing stimulation conducted on coal cubes showed the coal was effectively fractured with enormous cracks and voids. By using three-dimension computed-tomography (CT), the fracture extension and propagation in the coals are found to be obvious and extensive. Though the existing fracture greatly affects the new fracture development in vertical direction, the horizontal fractures parallel with the bedding plane direction are more likely to occur and even expand across the entire tested coal core. The dramatic coal permeability improvement (over a hundred times) after EHD also validates the cutting-through fractures, as does the enhancement of pore and porosity observed by morphology and structural characterisation via scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP).

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

20704 - Energy and fuels

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Journal of Natural Gas Science and Engineering

ISSN

1875-5100

e-ISSN

—

Svazek periodika

66

Číslo periodika v rámci svazku

June

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

10

Strana od-do

255-264

Kód UT WoS článku

000467062800022

EID výsledku v databázi Scopus

2-s2.0-85064257447