Genetic types of lake reef limestone traps and its control over oil and gas pool formation

Key words:  reservoir characteristics  reef limestone traps  genetic types  controlling reservoir  Zhanhua depression

Abstract:

During the period of the upper part of the Es₄ formation of Paleogene, Sikou sag and peripheral area of Zhanhua depression developed reef limestone. Based on the slices observation and cores analysis and test, combined with the analysis of reservoir quality and strata correlation, the reef limestone reservoir characteristics and controlling factor of available traps formation were studied. And the genetic types of reef limestone traps were classified and its control over reservoir formation was discussed. The results show that the lake reefs only developed in peculiar formation, have different sizes, and reef and reef flat are chaotic, superimposed and cross connected. The reef reservoir quality is highly heterogeneous. The formation of available reservoir is affected by sedimentary facies, diagenesis and tectonic movement. Four genetic types of reef limestone traps were classified,which has double influences on the oil and gas pool formation. The types of reef limestone traps are related to tarp 's validity, and play an essential role on reservoir formation time, migration pathway and the types of injection.