Abstract:

Central Iranian basin is one of the main overseas hydrocarbon exploration areas,in which,Kashan area is the first SINOPEC hydrocarbon exploration one.Based on the fieldwork and the comprehensive research on geology,geophysics and geochemistry,the authors of this paper study the hydrocarbon geology conditions of Kashan area in Central Iranian Basin.The main

reservoir rocks in the area are middle-late Oligocene to late Miocene Qom Formation,which is a typical porous-fractured carbonates with terrigenous and volcanic fragments.Central Iranian basin is a retro-arc foreland basin,in which,there are many structural traps.The maintenance condition is very good because of the huge thickness of mudstone and gypsum in Kashan area.There are three sets of source rocks of Jurassic Shemshak Formation,Cretaceous mudstone and Qom Formation.However,the quality of the source rocks is not good enough.The fluids containing hydrocarbon filled into Qom Formation in wells Arn-2 and Fkh-1 3 or 4 times respectively.The fluids,filling Qom Formation in wells Arn-2 and Fkh-1,are different from the fluids in well Arn-1.The fluids in well Arn-1 is oil,and the fluids in wells Arn-2 and Fkh-1 are gas with or without nitrogen.At last,it is suggested that the quality evaluation,estimation of hydrocarbon resource quantity and prediction of fractures should be deeply studied firstly in the process of the petroleum exploration in Central Iranian Basin.

Key words: hydrocarbon geology condition, carbonate rock, fractured reservoir, Qom Formation, Central Iranian Basin, Kashan area