Simulation Study On Spontaneous Imbibition Mechanism Of Tight Reservoir Rocks With Computational Fluid Dynamics

With the reduction of conventional oil and gas resources,the increase of world oil and gas resources demand and the development of oil and gas reservoir development technology,the exploitation of tight oil and gas reservoirs has become a hot spot at home and abroad.For tight oil and gas reservoirs,conventional waterflooding are not able to achieve a good development results because the breakthrough and logging of water in the late stage.It is found that spontaneous imbibition is an effective method to solve these problems.So it's important to study the scheme and mechanism of spontaneous imbibition.In order to study the mechanism of various factors on the spontaneous imbibition in tight reservoir rocks,a computational fluid dynamics simulation study was conducted by computational fluid dynamics simulation software Open FOAM in the pores of real tight reservoir rocks.The simulation method of multiphase flow is choosen to be VOF method.Firstly,the spontaneous imbibition in tight reservoir rocks under three common boundary types of OEO,TEO and TEO-OW was studied.The characteristics of spontaneous imbibition and the behavior of fluid flow were analyzed.It was found that reverse imbibition happened at both the OEO boundary and the TEO boundary.Under the TEO-OW boundary,both reverse imbibition and co-imbibition happens.Then,the effect of oil phase viscosity,interfacial tension and rock wettability on spontaneous imbibition in tight reservoir rocks were studied under OEO boundary conditions.It it found that the fluid viscosity affects the imbibition rate.The oil-water interfacial tension and the rock wettability affect the imbibition rate and the degree of imbibition.The influence of these reservoir parameters on spontaneous imbibition is obtained.The imbibition rate increases with the oil viscosity.The imbibition rate is of positive relevance with the interfacial tension,and the imbibition recovery is of positive relevance with the interfacial tension within certain range.While both the imbibition rate and recovery is of positive relevance with the rock wettability.The research results of the thesis have certain guiding significance to the design of reasonable exploitation plan for different tight oil and gas reservoirs in different on-site conditions.