Imbibition Characteristics And Water Lock Damage Evaluation Of Tight Oil Reservoir In Jimusar

After the fracturing construction of Tight Oil Reservoir in the Jimusar,the backflow rate of fracturing fluid is low,and a large amount of liquid is retained and absorbed by the reservoir.Fluid spontaneous imbibition and water lock damage caused by imbibition has become a problem which can't be ignored in reservoir development.Throughout the study of domestic and foreign scholars found that most of the research on the imbibition of conventional sandstone,tight oil reservoir especially in Xinjiang area,the spontaneous imbibition researches are less,the law of spontaneous imbibition in many tight oil reservoir is not clear.In this paper,the physical properties,the spontaneous imbibition characteristics and the water lock damage caused by the imbibition are evaluated by the indoor physical experiment,the core spontaneous imbibition test and the water lock damage experiment.Got the following results:(1)The total amount of clay minerals in the reservoir is less,the water saturation of the binding water is higher,the reservoir core is slightly water wet.The whole structure of the reservoir is dense,the fracture development is poor,the pore structure is complex,and the nanometer micropores are mainly intercalated and intergranular pores.The study reservoir area have poor physical properties;the porosity is 2.62%~13.44%,and the permeability before washing oil is 0.001~0.003 m D.(2)According to the different characteristics of the core water imbibition curve of the study area,the difference between the different types is large,and the imbibition is more complicated.The factors influencing the core imbibition in the study area are analyzed.It is found that the main factors affecting the ability of the core imbibition include poroperm characteristics,pore structure,irreducible water saturation,wettability and temperature.(3)The spontaneous imbibition of the reservoir in the study area will cause more serious water lock damage.The experimental results show that the stronger the spontaneous imbibition capacity of the core,the higher the degree of water lock damage.The clay mineral will deepen the reservoir water lock damage degree,but the total amount of clay minerals in the study area is low and the water sensitivity is low.It is recommended to reduce the damage of reservoir water lock by strengthening back row or selecting water lock inhibitor.