Study On The Paleokarst And Capacity Of Reservoir And Permeation Of Ordovician In The Western Region Of Lungu, Tarim Basin

Reservoirs of Ordovician in Tarim basin had been through multiphase tectonic events and several karsts superimposed reformation since Ordovician. Carbonate reservoirs that are thought to be related to paleokarst are difficult to forecast and explore because of complicated fractured-vuggy system. The characteristics of karst reservoirs in western Lungu is one of the key factors that control the exploration effects, however distribution rules of reservoirs are still unclear. It’s necessary, therefore, to have a systemic study of the evolution mechanism of carbonate paleo-karst reservoir and its control on the characteristics of oil and gas reservoir.Based on the study of previous literatures and former research results, several updating sedimentary theories and methods, including earth system science, Karst formation conditions and karst’s hydrodynamics, analysis of karst causes, dynamic correlation analysis of ancient hydrology and analogy method between paleo and modern karst, are applied in this thesis. Combining with widespread field work, indoor’s synthetic research is carefully done with qualitative analysis, induction, reasoning using modern analytical tools. Through intensive investigation, a comprehensive understanding and collection of papers about the theoretical information and data, empirical estimates and comprehensive analysis have been done. On basis of the comprehensive analysis of karst features, taking systematical summary and research on the characteristics of Ordovician paleo-karst in the Lower Paleozoic in western Lungu in order to master karst formation conditions, controlling factors and their impact on the oil and gas reservoir. The concept of paleo-karst reservoir permeability system was first proposed, defining its content, analyzing its compositions and reseaching its influence factors, deeply studying different paleo-karst geomorphic units, systematically analyzing the development features of karst system, summarizing the development laws of karst reservoir with different paleo-karst geomorphic units, discussing its development model, researching on the mechanism of paleo-karst and its control factors, confirming its stages, systematically discussing the reservoir permeability system in different geomorphic units and finally predicting play zone.This study has important theoretical and practical value. It is closely related to the exploration and production in western Lungu and also plays an important guidance role in the disposition of petroleum exploration in southern Lungu to find new play reservoir blocks. This thesis provides a scientific basis for oil and gas development.