Study on hydrocarbon-generation evolution and prediction of favorable exploration areas in Gucheng area of Tarim basin

摘要

Lower Ordovician and Cambrian are the good source rocks in Gucheng area compared to the other areas in the east of Tarim Basin. During the early of Caledonian movement after Upper Ordovician deposited, the source rocks of Lower Ordovician quickly went into gate of Hydrocarbon-generation and generated oil & gas. Because the time was so short and buried depth was so deep, the generated oil is not able to be expulsed from source rocks and they had been cracked to generated gas along with source rocks, which Hydrocarbon-generation didn't stop until the source rocks arrived at the dead line of natural gas generated. In the following tectonic movements, the buried depth and temperature didn't measure up to the conditions and the thermal evolution of source rocks had reached the dead line of natural gas generation after Caledonian movement, and no gas could generate. Used SPI, we conclude that the forming pattern of reservoirs is self-generating and self-preserving based on analysis of lithologic characteristics. The favorable exploration areas are located in Paleo-accumulation in the Palaeozoic group, especially dolomite reservoir in Cambrian.