Study On The Law Of Hydraulic Crack Initiation And Propagation Of Single Plane Perforation

Hydraulic fracturing is one of the most important measures of oilfield development, crack propagation along the direction of maximum main stress on the condition of convention helical perforation in the tight and unconventional reservoir, cannot control the direction of crack, and fracturing effect is influenced. Single plane perforation is the latest perforation technology for unconventional reservoir. It is beneficial to reducing crack initiation pressure and forming complicated crack, and this technology has an important meaning to enhanced the producing area of reservoir.In this paper, the rock mechanics, plastoelasticity, damage mechanics and seepage mechanics are combined, and establish the mechanical model and finite element model of fracture breakdown on the condition of single plane perforation on the basis of considering the coupling effect of seepage rock deformation by the computing platform of ABAQUS. To calculate the initiation pressure of single plane perforation according to the maximum tensile stress theory based on the consideration of cumulative impact on the ground stress near wellbore caused by the process of drilling-cementing-perforation, and the change law and influence factors of hydraulic crack initiation pressure on the condition of single plane perforation is obtained. To combine with the technology of extended finite element, the extended finite element model of crack propagation is established after analysis the distributing rule of ground stress when the fracture breakdown. The fracturing fluid injection perforating tunnel through the preset crack, observe the crack propagation morphology under different injection time, and then hydraulic crack propagation morphology of single plane perforation is obtained.It can be seen from the theoretical analysis that there were greater effect of distributing rule of ground stress, the angle of wellbore, the angle between perforations and perforating diameter on the crack initiation pressure of single plane perforation, and perforating depth has little influence on crack initiation pressure in horizontal well; The well drainage area formed by the crack propagation of single plane perforation is much higher than that of the helical perforation, and perforation in the direction of minimum main stress, the ideal symmetric main fracture is formed on the condition of stress type is normal fault, and a complex network fracture is formed on the condition of stress type is reverse fault.In order to verify the feasibility of single plane perforation, analyzed the effect of perforation on the strength of casing through the ground antiknock test, on this basis, single plane perforation is applied to actual wells in the field, the crack initiation pressure of single plane perforation is obtained through fracturing operation, validity and feasibility of theoretical analysis is verified by comparing the field rusults with the theoretical results. The research results above can provide theoretical basis for the widely applied of single plane perforation in the tight and unconventional reservoir which has directive significance for the actual production.