Study On The Real-time Detection And Formation Mechanism Of Mud Shale Crack Net Based On Dynamic Cracking

Shale gas is a new energy source in the 21 st century.Today's shale gas is produced in a single way,often by hydraulic fracturing.Up to now,people do not fully understand the characteristics of new unconventional energy reservoirs,and there is no effective exploitation scheme,which leads to the low efficiency of shale gas extraction and a large amount of resource waste.Therefore,research on how to improve the efficiency of shale gas reservoir transformation is of great practical significance.In this paper,a new method of rock cracking is put forward,which adopts the methods of relevant laboratory tests and numerical simulation,and then combines with the existing theories to analyze the feasibility and effect of this method.Firstly,the model of rock mass is made of similar materials,and the effect of different dynamic load conditions is artificially added to simulate the movement inside the rock mass,so as to achieve the effect of producing different crack networks inside the rock mass.Secondly,the traditional indoor seepage test was used to evaluate the permeability of rock mass under different dynamic loads,and relevant electrochemical data were measured by embedding conductive materials and wires at the outlet of the device and connecting them to the electrochemical workstation.Finally,ANSYS/ ls-dyna numerical analysis software was used to establish the relevant experimental model and set different parameters,that is,different shale fracture networks were generated under different conditions,so as to analyze the formation mechanism of shale fracture networks.The results show that :(1)the value of permeability coefficient obtained by the self-designed rock cracking and rock cracking net detection device is significantly greater than the classical value of permeability coefficient,indicating that the dynamic cracking method has obvious effect.(2)at the same time,the phase Angle of rock models with different degrees of dynamic load splitting is greatly different in the low frequency band.With the increase of frequency band,the difference gradually decreases,and the phase Angle of each rock model in the high frequency band finally reaches a relatively uniform level.(3)the placement of explosives and the number of explosives play a crucial role in the cracking effect inside the rock mass.Relatively long and narrow cracks are formed after relatively long and thin explosives crack the rock,while relatively wide cracks are formed after relativelylong and thick explosives crack the rock.(4)the relatively large amounts of explosives inside the rock crack process compared to a relatively small amount of explosives inside the rock crack process,although both the process time is short,but the overall length of the former than the latter's overall length,the former is "energy is large,fast",which show the "small energy,slow".On the whole,the laboratory tests and numerical simulations have proved that dynamic cracking is an effective method for the exploitation of mud shale,which can be further studied.The research results have important engineering significance and reference value for exploring new ways of shale cracking and improving the production efficiency of shale.