Research On The Genetic Mechanism Of Ordovician Reservoirs In Shunbei Area

Carbonate hydrocarbon resourses play an important role in the world's resourses,and the carbonate hydrocarbon accumulation research has been the hot point in the petroleum geology study.The Shunbei region of Tarim Basin is located in Xinjiang Shaya County.In early exploration,in Shunbei 1 well drilling process,the oil and gas was found in Ordovician carbonate rocks,and then,many drilling wells in main fault zone of Shunbei region has been tested and found high-yielding industrial oil flow,It is indicated that the ordovician reservoir in Shunbei region is mainly distributed in Yijianfang and Yingshan formation,and its hydrocarbon accumulation conditions are superior.The main fault zone is a favorable area for hydrocarbon accumulation.As a new bright spot in tarim basin's petroleum exploration,Shunbei region has huge potential resources.But the level of exploration in the new area is still low.There are still some problems in reservoir type,genetic mechanism and reservoir prediction.To a certain extent,it restricts the further exploration of the Shunbei region.Therefore,the research purpose layer of this paper is Ordovician's Yijianfang and Yingshan formation in Shunbei region of Tarim Basin,relying on the major pilot project of Sinopec northwest oil field branch"Oil and gas accumulation law and optimization of exploration breakthrough targets of carbonate rocks" sub items,After a lot of research and study of predecessors' research results,as the theoretical guidance on carbonate reservoir geology,integrated using the sedimentary petrology,structural geology,reservoir geochemistry theory,and making full use of existing data,combining with thin section identification,cathodoluminescence,geochemical analysis and so on,Surrounding diagenesis and reservoir characteristics,researching the structural features,petrographic features,sedimentary facies,diagenesis type,diagenetic evolution sequence,reservoir space type,etc.of Ordovician reservoir in Shunbei region,and to analyze the mechanism of reservoir formation,to predict a good carbonate reservoir:By observing and identifying the existing drilling core and rock thin section,the rock types of ordovician reservoirs in Shunbei region are mainly limestone,with transitional rocks and other rocks.After a summary of the characteristics and distribution rules of the rocks in the target strata,it is believed that the sedimentary facies of this region is mainly composed of carbonate open platform facies,and can be subdivided into two main sub-facies of intraplatform shoal and Platform subfacies.Through the detailed identification of the rock thin section under the microscope,It is believed that the main diagenesis in this region is cementation,compaction,corrosion,dolomitization and silicification,etc.In addition,summarize the diagenetic characteristics and diagenetic results in different zones and different strata,and divide diagenetic evolution stages,and describe the changing features of diagenetic sequence and pore evolution.In the aspect of reservoir space,through drilling core observation and rock thin section identification,combining with the porosity and permeability test data and using geophysical data(drilling,conventional logging and imaging logging,etc.)to summarize the characteristic of effective reservoir space,comprehensive identification and classification purpose layer in the main reservoir type are fracture type.It mainly include main crack-hole,solution pores.In combination with characteristics of diagenesis,diagenesis and reservoir development results,analysis of different types of reservoir formation mechanism,and sums up the consistent with the actual geological conditions of reservoir formation in this area.Then it is believed that tectonic fracture activity and atmospheric corrosion is the main controlling factors of reservoir development,and finally to predict the distribution of favorable reservoir in turn.