Study On The Spontaneous Imbibition Effect Of Tight Sandstone Gas Reservoirs In Sulige

The tight sandstone gas field has a wide distribution range,the reservoir heterogeneity is strong,and the capillary force phenomenon is very obvious.At present,"fracture fracturing + imbibition replacement + unlocking back row" is a new attempt to effectively develop tight sandstone reservoirs.Fracturing fluid is not only a carrier for sand-sanding,but also a tool for replacement,but more imbibition displacement means higher recovery and also indicates more serious water lock damage.Therefore,it is of great significance to strengthen the study of the infiltration of tight sandstone gas reservoirs and the evaluation of water lock damage to improve reservoir productivity.In this paper,the tight sandstone reservoirs of He 8 in the Sulige area are the main research objects.The indoor core experiments are the main research methods.The mechanism of different types of tight sandstone reservoir fracturing fluid imbibition and water lock is systematically studied,and different types of tight sandstones are analyzed.The static and dynamic characteristics of the reservoir fracturing fluid are obtained,and the following research results and understanding are obtained:(1)The permeability is positively correlated with the gas replacement rate.As the permeability increases,the gas replacement rate of the core increases,and as the core permeability increases,the time taken for the spontaneous infiltration of the core to stabilize is shorter.The interfacial tension has a significant influence on the spontaneous imbibition of the core.For different cores,the influence of interfacial tension on the core imbibition has an optimal value for the best imbibition.The degree of mineralization of the osmotic liquid is negatively correlated with the rate of core infiltration.The greater the degree of mineralization of the osmotic solution,the worse the osmotic pressure difference caused by the difference in mineralization is not conducive to the spontaneous imbibition process of the core,but for different cores,Since various types of mineral components existing inside the core react with each other after salt water,the effect of the mineralization on the spontaneous imbibition of the core is multifaceted.The temperature has a significant effect on the spontaneous imbibition of the core.The gas replacement rate of the core at high temperature is much higher than the gas replacement rate at normal temperature.The influence of various factors on the spontaneous imbibition of the core is considered to be the greatest influence of the interface tension,followed by the temperature,permeability and mineralization.(2)The initial permeability of the core is negatively correlated with the degree of water lock damage.As the initial permeability increases,the degree of water lock damage of the core decreases,and 0.1mD is the critical point.For cores with a permeability of less than 0.1 mD,the water lock damage decreases sharply with the increase of permeability,and the core with a permeability greater than 0.1 mD has a relatively small change in water lock damage with permeability.Interfacial tension has a significant effect on the water lock damage of the core.The greater the mineralization degree of the imbibition solution,the more serious the water lock damage of the core.Salting out is also an important factor that causes the core to be more severely damaged by water locks in salt water.The temperature has a certain relief effect on the water lock phenomenon of the core,and the two are positively correlated.The higher the temperature,the lower the damage degree of the water lock.