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Abstract: To figure out the oil and gas distribution pattern in the Tarim Basin, the adjustment and reformation of oil and gas reservoirs under the background of late Himalayan Orogeny are analyzed. Strongly affected by the tectonic movement, the oil and gas reservoirs in the Tarim Basin experienced secondary actions in physical adjustment and chemical alteration: on the one hand, during the course of physical adjustment, reversed strata caused the early-formed oil to seep vertically and to migrate laterally along the sandstone in large scale with long distance; on the other hand, in the process of chemical alteration, the deposition of massive strata accelerated the thermal evolution of organic matter, generating large amounts of cracking gas, which went into the pre-existing reservoirs and led to big change in oil and gas properties and the coexistence of heavy oil, light oil, waxy oil and condensate gas in the same area. The physical adjustment and chemical reformation of oil and gas reservoirs in late Himalayan period resulted in the lateral differential distribution of oil and gas in large area and multiple vertical oil-bearing layers with complex and diverse oil and gas properties. [Copyright &y& Elsevier]

The adjustment of primary hydrocarbon reservoirs in marine formations is an important feature of the oil pools in the Tarim Basin. Large-scale hydrocarbon adjustment is related to the strong regional tectonic movements, which is always accompanied by extensive migration of basin fluids including diagenetic and mineralizing fluids. Organic fluid inclusions are well developed in hydrothermal minerals, such as fluorite, which have been found in the dissolution-enlarged fractures or karstification caves in the Ordovician in the central Tarim Basin. Proved by well drilling, the fluorite deposit is good reservoir for oil and gas. So the peculiar accompanied or superimposed relationship between fluorite hydrothermal fluid mineralization and hydrocarbon migration and accumulation exists in the Ordovician in the central Tarim Basin. Considering regional tectonic setting and mineralization condition, through different kinds of analytic methods including electron spin resonance dating, fluid inclusion laser Raman and colonial inclusions hydrocarbon fossil analysis, we proposed that extensive mineralizing fluids and hydrocarbon migration occurred in late Yanshan-Himalayan (110.4-30.8 Ma) period, and Himalayan, especially, is an important period for hydrocarbon accumulation from 34.3 Ma to present. [ABSTRACT FROM AUTHOR]