In order to study the changing law of fracture initiation pressure and fracture initiation loca-tion of hydraulic boreholes under fracturing conditions of different rock media,two classical models were compared:continuous medium elasticity theory and discontinuous medium fracture theory by com-bing the existing theories.Nine mines such as Wangjialing Coal Mine are taken as the research object,the indoor test was carried out and the results were compared,according to the fracturing conditions of rock drilling in different media,and the comparative analysis method was used to further examine the influence of surrounding rock pressure and compressive strength on the fracture initiation pressure and fracture initiation position.The results show that in different stress environments,the larger the lateral pressure coefficient is;the larger the fracturing pressure required for drilling and cracking of two kinds of rock media is,the larger the difference is,the smaller the difference is(the ratio of the two kinds of pressure difference to the initiation pressure of continuous media rock),and when the lateral pressure coefficient is larger than 2,the difference is infinitely close to 0;the compressive strengths of rocks of different media are different,and the larger the compressive strengths are,the larger the fracturing pres-sures of the two kinds of media are;the location of fracturing in the theory is related to the surrounding rock pressure,compressive strength,and fracturing location of continuous media;the fracturing position of continuous medium is related to the surrounding rock pressure and compressive strength.The loca-tion of crack initiation in the theory is positively correlated with the surrounding rock pressure and com-pressive strength,and the location of crack initiation in the theory of discontinuous media is always a-long the horizontal stress direction.The influence of rock medium on the expansion law of hydraulic fractures can provide reference for the selection of theoretical model,and also help to predict the frac-ture initiation and propagation behaviours.
关键词
水力压裂/裂隙扩展/理论模型/比较分析法/扩展规律
Key words
hydraulic fracturing/fracture propagation/theoretical model/comparative analysis/propaga-tion law
维普
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