Finite Element Study Of Tension Crack Propagation In Sandstone Formation

Sandstone formation is the main oil and gas reservoir.With the development and utilization of oil and gas resources,the exploration and development of oil and gas gradually shifted from conventional oil and gas reservoirs to special oil and gas reservoirs,which the exploration and development of fractured reservoirs is particularly important.In the sandstone reservoir with fracture,the crack extension law plays a key role in the development of fractured reservoir.Based on the analysis of tension crack extension mechanism in sandstone formation mainly from the angle of fracture mechanics in the ABAQUS platform,the numerical simulation of tensile crack is carried out by the extended finite element method.Mainly from three aspects to carry on the simulation: First,the static simulation.The stress intensity factor of the single side crack with the center crack in the sandstone stratum is obtained by the ABAQUS software.By analyzing the influence of the grid density,the crack length,the crack inclination angle and other parameters on the stress intensity factor,the dynamic analysis of the crack propagation is made.The second step,dynamic extended simulation.Combined with the stress intensity factor in the static simulation,the simulation of tensile crack growth is carried out the crack in the middle of a small plane did not follow the initial crack extension in the simulations that explant the crack is subjected to tensile stress in the shear stress at the same time,It conforms to the actual situation.In this paper,the II type crack and I-II compound crack are simulated.Third,the relationship between the length and width of cracks in hydraulic fracturing is discussed by using the extension law of sandstone cracks.It is concluded that the sandstone formation of crack fracture surface is in accordance with the approximate linear expansion,II type crack,I-II composite is the first crack along the crack surface expansion,then according to the maximum circumferential tensile stress direction expansion.