A Quantitative Microscopic Model of Hydrcarbon Accumulation

Key words: 
• hydrocarbon accumulation /
• microstructure /
• quantitative model /
• microscopic proccess /
• stage concept model /
• distribution model /
• coordination number

Abstract: Because both migration and accumulation of oil and gas proceeded within the pore space of reservoir,the porosity structures directly have an effect on the accumulation of oil and gas as well as the formation and distribution of oil and gas reservoirs. Based on pore microstructure,the microscopic process of hydrocarbon accumulation is quantitatively studied by proposing three stages and relevant concepts models,which inclueds early migration with resistance force,interim accumulation and late filling. Several models of hydrocarbon accumulation and distrbution are also presented respectively according to the related serial complex traps and simple traps that are composed of various porelevel heterogeneous reservoirs.In homogeneous reservoir hydrocarbon accumulation is similar to capillary pressure curve and the change of oil saturation in reservoir directly has something to do with depth or height of oil column,it is also to say that oil saturation on the bottom of reservoir(nearly from the oil-water conatct)is lower,while oil saturation on the top of reservior is higher. In heterogeneous reservoir,the features of hydrocarbon accumilation are very complex,and,sometimes, it has regular features that oil saturation on the bottom of reservoir (nearly from the oil-water contact) is lower,while oil saturation on the top of reservoir is higher,but sometimes it has contrary ones,because of characteristics of internal combination in reservior.In serial traps,hydrocarbon accumulation has something to do with lots of macroscopic factors of reservoir that includes intercalated beds,different graded combination of pore structure type,connectedness of reservoir and so on. The conclusion makes a good complement to the traditional theories of petroleum geology.The study is also proved a successful attempt in quatitative geology.