Formation and distribution characteristics of unconventional oil and gas reservoirs
Song Yan1, 2, Jiang Lin2, Ma Xingzhi2
1 Unconventional Gas Research Institute, China University of Petroleum(Beijing), Beijing102249 2 Research Institute of Petroleum Exploration and Development, PetroChina, Beijing100083
Abstract：Unconventional oil and gas, the hot field of petroleum exploration and development, is the future development trend of petroleum industry. The research on the accumulation of unconventional oil and gas has a significant guide for its exploration. The distinction between conventional and unconventional oil and gas accumulations is that buoyancy is not the primary driving force of hydrocarbon accumulation for unconventional oil and gas. The reason is that abundant micro-nano pore in tight reservoir causes a large capillary resistance for hydrocarbon migration. Also there is no advantage natural condition and evidences for providing strong buoyancy. According to the relationship between source rock evolution and unconventional oil and gas accumulation, the unconventional oil and gas resource is divided into six types including oil shale, shale oil, tight oil, shale gas, tight gas and coalbed methane. The characteristics of source reservoir assemblage of oil shale, shale oil, coalbed methane and shale gas is that the source rock is just the reservoir itself. However, there are two source reservoir assemblage types for tight oil and gas. One type is that the reservoir touches|the source rock with the superposition style. The other type is that the reservoir is close to the source rock but with a little distances, which is similar to conventional oil and gas reservoir. The differences in accumulation dynamic cause that the unconventional oil and gas reservoir shows many significant geological characteristics including hydrocarbon extensive distribution, petroleum local enrichment, retention or short distance migration, no noticeable trap boundary and no unify oil-water interface.
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