Study On Formation Mechanisms Of Pressure Characteristics Of Large-scale Fracturing High-stop Pump In Hailar Oilfield

Hailar Oilfield is rich in oil and gas resources and is currently a key area for exploration and development of Daqing Oilfield.However,due to the extremely complicated geological conditions,the reservoir rocks are diverse,and the fracturing construction is prone to sand plugging.In order to achieve the research of fracturing well technology and improve the effect of fracturing stimulation,it is critical to determine the formation mechanisms of high stop pump pressure characteristics.The rock composition of the reservoir was analyzed by polarized light microscopy,X-ray diffraction analysis and X-ray diffraction clay mineral content analysis.The cement type and cementation method of each reservoir were analyzed by rock sample identification experiment.The Triaxial compression,brittleness evaluation and ground stress test,tensile strength test and fracture toughness test yield the mechanical parameters of the reservoir rock.The influence of rock mechanics parameters on the geostress field was analyzed according to simulation of stress field.The digital model software was used to analyze the crack initiation and extension of reservoir artificial cracks.The results show that the lithology of various reservoirs in Hailar Oilfield is variable,and the content of clay minerals in the Xing’anling Formation can reach up to 37%;the total is composed of calcite,iron dolomite and clay cement,point-to-line contact;the rock’s Young’s modulus is mainly concentrated at 0.76×10⁴MPa～3.84×10⁴MPa,Poisson’s ratio is more than0.34,Nantun formation reservoir brittleness up to 0.699,the minimum horizontal principal stress gradient is 0.014MPa/m～0.017MPa/m,the tensile strength is more than 6MPa,and the fracture toughness is less than 1MPa/m^0.5.The analysis shows that the rock toughness（Young’s modulus,Poisson’s ratio）,high clay and cementation of the rock in the Hailar Oilfield increase the fracture and extension pressure,and the high ground stress in some areas increases the construction difficulty.The features of the increasing pump stop pressure is presented.