Molecular Dynamics Simulation Of Shale Oil Occurrence Characteristics

Shale oil resources are widely distributed in our country,and good shale oil has been found in Songliao,Ordos and Bohai Bay basins.The exploration potential is huge.To study the adsorption state and free state ratio of shale oil in shale reservoir and the wettability of shale reservoir minerals is the basis for evaluating the fluidity and momentum of shale oil and finding the favorable area for shale oil exploitation.Rock oil resources exploration,resource assessment,development methods and other aspects are of great significance.Based on the Qingshankou Formation in the Songliao Basin,this study designed a macroscopic wettability experiment of "oil-water-minerals" of reservoir minerals.By means of molecular dynamics simulations,the "oil-water-minerals " Micro-wettability and oil-water wettability of organic matter were studied.Two types of shale oil models were designed according to the types of paraffins common to shale oil and the elemental composition of shale oil.Molecular dynamics simulations were performed to investigate the effects of nanoscale The adsorption characteristics of shale oil in organic slits and mineral slits,the occurrence characteristics of shale oil from two aspects of wettability and adsorption,in order to provide some reference value for the study of shale oil occurrence mechanism,Advances in research on shale oil occurrence and migration.It is found that the lipophilicity of minerals in water phase from strong to weak is mica> pyrite> calcite> dolomite> quartz;mineral type,oil component type and salinity of water all have great influence on the contact angle,With the increase of n-octadecane in the oil droplets,the contact angle of the oil droplets on the mica surface becomes smaller,the wettability becomes better,and the wettability on the surface of other minerals is slightly different.With the increase of water salinity,The contact angle of oil droplets on the surface of mica shows a tendency to become significantly larger,the wettability gradually deteriorates,and the wettability on other mineral surfaces is slightly different.Through the molecular dynamics simulation of the micro-wettability of the reservoir minerals,it is found that under the geological conditions,the organic matter is completely oil wet,most of the minerals in the reservoir are water wet,and the clay minerals have higher water and oil Adsorption and temperature increase can reduce the wettability of reservoir minerals to oil,and the pressure conditions have little influence on the mineral wettability of reservoir.It is found that the type of shale oil has a great influence on the adsorption state and free state of shale oil.The shale oil containing more heavy hydrocarbon also has larger adsorption capacity.Different kinds of slits Adsorption capacity is also different: organic slits> organic matter-mineral slits> mineral slits,calcite slits on the heteroatom shale oil molecules adsorption capacity;shale oil adsorption capacity of different components,heavy hydrocarbons adsorption Its ability is stronger than that of light hydrocarbon.The aromatic hydrocarbons with special chemical bonds have stronger adsorption capacity and more adsorption on the wall of the slit.The increase of temperature leads to the decrease of adsorption amount of shale oil and the adsorption of shale oil under pressure Minor sexual effects.