Physical Simulation Experiment On Acidizing Fracturing Of Fractured Carbonate Rock

The oil and gas resources in the Tahe Oilfield are rich,and the main storage space of reservoir are natural fractures and pores.The permeability of matrix is low,and some wells fail to drill into the reservoir.In order to realize the accurate connection of the reservoir around the wellbore,it is necessary to transform the traditional one-way fracturing mode into targeted fracturing mode.It is not clear how to achieve targeted fracturing and the factors that affect targeted fracturing are also unknown.Based on this,this paper through the experimental research and theoretical analysis,mainly completed the following aspects:(1)Establishment of targeted fracturing model for carbonate formationsIn this paper,the targeted fracturing model is established,and the matlab program is used to simulate the influence of different factors on the fracture propagation.It is found that increasing the bottom hole pressure,the perforation length and the rock Poisson's ratio,or reducing perforation azimuth angle and the rock elastic modulus will increase the vertical displacement and the swept area of the hydraulic fracture,but the importance of each factor is different.(2)Physical experiment simulation of mechanical parameters of rock when acidizing fracturingIn this paper,the change of the mechanical properties of the limestone outcrop were investigated by using the GCTS-RTR-1500 high temperature and high pressure rock mechanics testing machine.Under the experimental conditions,the triaxial compressive strength of the rock samples decreased by 41.2%,the elastic modulus decreased by 54%,the Poisson's ratio increased from 0.24 to 0.35,and the strength of the rock samples was weakened.Acid etching will help to improve the ability to connect the target reservoir when fracturing.(3)Extension of hydraulic fractures in fractured carbonate formationsIn this paper,the interaction between hydraulic fractures and natural fractures and holes are simulated by the real triaxial physical fracturing experimental apparatus.This paper mainly simulates the interaction between hydraulic fracture which is changing its orientation and nature fracture,and confirm the possibility of forming fractured networks of the simulated layer.Three modes of interaction between hydraulic fractures and natural pores were confirmed through the physical experiment,including: stopping the expansion;penetration;completing the reorientation process along the expected trajectory.