ACOUSTIC EMISSION CHARACTREISTICS OF TIGHT SANDSTONE WITH A BOREHOLE UNDER BRAZIL DISK SPLIT TEST

Through Brazilian experiment which we used tight sandstone rock samples from tight oil and gas reservoirs in Ordos Basin, the rock failure process of time-load curve, as well as the cumulative number of AE and AE energy rate curve over time was obtained. The relations between Acoustic Emission characteristics and load value was analyzedby observing the entire process of rock failure. The difference of rock Acoustic Emission between two different drilling state was compared. The results show that using AE characteristic parameter can represent the whole process of rock failure very well. The void space of AE event is closely related with rock formation.whenthe position of macro rupture is relatively complete, it is generally able to monitor the AE void space,when position of macro rupture is incomplete, the AE void space may not happen. According to the above features, we can judge the integrity of the crack at the position of macro crack coalescence. As can be seen from the spectrum of AE events, there are two main different types of AE in rock failure process, namely the original initial crack defect closure AE and rock fracture generated AE,the difference between the two is obvious.