Rock Fracture During Oil Well Perforation

Rock stress fields in the near wellbore of an oil well during perforation are modelled and studied numerically. The main parameters that influence the stress field of rocks during perforation are identified. The dynamic stress field formed in the near wellbore zone causes degradation of reservoir properties and annular zones of rock fracture formed around a production wellbore. The model of porous and permeable reservoir was built considering mechanical parameters such as Poisson’s ratio, Young’s modulus, coupling along the crack system, uniaxial compression strength and compressibility of cracks. The dynamics of rock fracture and stress state change were simulated using Finite Element Method. It is shown in the simulation that the type of perforation has a strong influence on the mechanism of rock fracture and distance of fracturing zone from the well. It is investigated in experiments that pressure drawdown between reservoir and bottomhole zones affects the formation stress state and as a result distribution of permeability and cracks opening.