Occurrence Characteristics And Mobility Of Tight Oil

Relieving the contradiction between China's supply and demand for oil and gas,in addition to the development of new energy,it is very important to accelerate the exploration and development of oil and gas in the unconventional fields,especially the tight oil and gas.At present,tight oil has become a key area of recent oil and gas exploration and development at home and abroad.In order to study the characteristics and mobility of oil in tight sandstone micro-nanometer pore throat systems.The tight sandstone samples from the Gaotaizi formation in the northern Songliao Basin were selected for physical property measurement,clay mineral analysis,field emission scanning electron microscope,high-pressure mercury injection,rate-controlled porosimetry,low temperature nitrogen adsorption,nuclear magnetic resonance,and tight oil displacement experiments.Using field emission scanning electron microscopy and rock mineral energy spectrum analysis,we observed that there are generally four types of reservoir space in the tight reservoirs of the Gaotaizi reservoir in the northern Songliao Basin:primary pores,dissolved pores,microfissures,and intercrystalline pores.Combining various experimental methods using rate-controlled porosimetry,high-pressure mercury injection,and low-temperature nitrogen adsorption,the full-aperture microstructure of Gaotaizi tight formation was characterized.The pore size of the samples in the study area is mainly distributed in 4-500 nm.Poor sample porosity is typical of tight reservoirs.In this dissertation,nuclear magnetic+displacement combined device was used to establish a nuclear magnetic+displacement research method for determining the occurrence and mobility of tight oil.Three types of nuclear magnetic+displacement experimental schemes were designed for tight oil reservoir forming and development process.Oil displacement water simulates the tight oil filling process;water disolacement oil simulates the development of tight oil;oil displacement gas simulates the geological process of tight oil displacement gas.The experimental results show that when oil is filled with tight reservoirs of formation water,the saturation of filling is affected by the distribution of the radius of the throat,and the proportion of oil in tight reservoirs filled into smaller holes is high.Oil-driven gas?oil-filled dry sample?is mainly based on 100-1000nm holes.Water displacement oil:Displacement is mainly based on the presence of oil in smaller pores.At the same time,a T₁-T₂ spectrum has been established to divide oil and water in different storage areas,which can more intuitively show the distribution of oil/water in different pore sizes.A physical simulation experiment of tight oil filling was conducted to study the mobility of tight oil in micro-nanometer systems.The flow pattern of the tight oil in the micro-nano pore throat system was studied by analyzing the characteristics of the relationship curve between the filling pressure,fluid flow,and oil saturation.The results showed that there was a good negative correlation between the starting pressure gradient and the permeability of surface water flooding oil;there was a good positive correlation with the mean pore throat radius ratio;the starting pressure gradient was weakly negative with the porosity and sorting coefficient.relationship.Start pressure,final charge oil saturation is controlled by the permeability/sorting factor.The starting pressure is negatively related to the permeability/separation factor,and the oil saturation is positively related to the permeability/sorting factor.