Abstract:

Based on data from drilling core, analysis assay and seismic data of the Central Tarim area, the authors deal systematically with the activities and mechanism of the deep fluid as well as its thermal effect on hydrocarbon accumulation. Based on the study for hydrothermal mineralization and alteration of Ordovician rock, paleothermal anomaly, inorganic CO₂ gas reservoir, inclusion temperature measurement and so on, the following conclusions are arrived: throught seismic, volcano or other variable channels such as fault, unconformity and so on, the deep fluid migrated upwards. Such fluid could improve not only the hydrocarbon-generation quantity and rate, but also lower the residual organic content in source rock and affects the hydrocarbon source rock evaluation. Deep fluid both has the destructive role of hydrothermal calcite filling and the constructive role of hydrothermal corrosion and hydrothermal secondary minerals for the gas reservoir. During the process of upward migration, abnormal high pressure caused by the deep hot fluid provides power for the secondary oil migration. For the thermal effect of gas formation, reservoir reconstruction and hydrocarbon accumulation dynamics，the deep fluid both has more important influence on the formation and evolution of the old reservoir in light of energy and material aspects，and make the origin of the hydrocarbon more complicated in Ordovician strata of the Central Tarim area.

Key words: deep fluids, fluid dynamics, heating effects, hydrocarbon reservoir, Central Tarim basin