Multi-fracture expansion law of hydraulic fracturing with different injection rates
To analyze the perforation parameters for hydraulic fracturing,we employ an independent developed device,i.e.TCHFSM-I type large true triaxial fracturing seepage simulation device.Combined with acoustic emission monitoring system and high-temperature and high-pressure dynamic flowmeter,carry out tests on homogeneous cement mortar specimens for the study on synchronous expansion law of hydraulic fractures with different injection rates.The results show that:with the increase of injection rate,the length and width of perforated fractures will increase to some extent.The inter-fracture interference will reduce,and the stress shadow effect decreases.The fracture expansion is more balanced,and the fracturing effect is better as the perforation spacing is larger.With the increase of injection rate,the fracture initiation pressure of perforation hydraulic fracture will increase,and the initiation time becomes shorter resulting in small effect of perforation spacing.Under different injection rates,the flow distribution of perforations is significantly different,and obviously affected by the perforation spacing.When the perforation spacings are 20 mm and 60 mm,the flow ratios of the middle perforation are 7.31%,10.88%,16.12%,31.12%,32.69%,33.44%,respectively.
hydraulic fracturinginjection ratessimultaneous expansion of multiple fracturesacoustic emission response characteristics