Study On The Occurrence And Flow Characteristics Of Shale Oil In Different Types Of Pores

Shale oil,as an important component of unconventional oil and gas,reveals the occurrence characteristics and flow behavior of shale oil,clarifies the spatial distribution and recoverable reserves of shale oil,and is a necessary prerequisite for studying the migration of shale oil and improving the recovery rate,which has significant implications for the exploration and development of shale oil.Based on the molecular dynamics simulation method,different types of shale pores were constructed,including organic matter pores(kerogen),inorganic matter pores(illite),and composite pores(kerogen-illite).Single-component and multi-component shale oil models were added to the pores to analyze the occurrence and flow characteristics of single-component shale oil in different types of pores,as well as the effects of pore size,temperature,maturity,and displacement force conditions on the occurrence and flow of shale oil.The study also investigated the occurrence and flow characteristics of multi-component shale oil in different types of pores,as well as the effects of fluid component proportions and wall component ratios on adsorption phase proportions,slip length,and viscosity.The study results show that:1.In organic matter pores,single-component shale oil will form an adsorption layer on the surface of the kerogen porous matrix based on initial adsorption,with a density peak of 75.08 1/nm~3.Increasing the maturity of organic matter and increasing the driving pressure difference to some extent are helpful for the flow of shale oil molecules.Long-chain alkanes and polar molecules containing benzene rings have stronger adsorption capabilities.Increasing pore size is beneficial for the extraction of light and heavy components.Increasing temperature mainly extracts intermediate components.2.In inorganic matter pores,the density distribution of single-component shale oil is uneven and shows symmetrical distribution along the center of the pore.The bulk phase velocity profile is parabolic,and the slip length is-0.37 nm.Increasing pore size weakens the wall effect on the bulk fluid,and the slip length increases to 0.24 nm.There may be competitive adsorption between toluene and naphthalene.A higher proportion of light components is more conducive to flow,while the high proportion of heavy components has better desorption effect.3.In composite pores,the density peak of the first adsorption layer fluid is 1.46times the density peak of the central fluid in the pore.Compared to the occurrence state,when the proportion of inorganic matter in the wall is high,the proportion of adsorption phase decreases by 2.45%,which is greater than the 1.10%decrease when the proportion of organic matter is high.A higher proportion of inorganic matter in the wall is more conducive to flow,and the adsorption strength of organic matter is higher than that of inorganic matter.The influence of friction coefficient on flow cannot be ignored.The research in this paper can provide some theoretical support for the occurrence state and flow characteristics of multi-component shale oil in pores considering the proportion of wall components.