Abstract:
Comparing with petroleum,natural gas is more active,and its accumulation and dissipation are more complex.In this paper,the characteristics of composition differentiation and carbon-isotope fractionation of natural gas in different carrying beds in migration are discussed according to the result of physical simulating experiment,and the influence of different carrying beds characteristics to natural gas is studied.The result of physical simulating experiment shows that chromatographic effect and fractionation of composition will take place when hydrocarbon migrating.The light-hydrocarbon composition in natural gas,such as methane,has relatively high permeability and migrating velocity.Clay minerals have more powerful bounding force to heavy-hydrocarbon composition than to light composition,and the migration velocities of normal paraffin hydrocarbons and isoalkines in different carrying beds are obviously different.The experimental result also shows that migration can cause the fractionation of carbon isotope of natural gas,and methane carbon isotope is comparatively sensitive to migration conditions and processes.