Reservoir Controlling Factors Of The Middle Triassic Lekoupo-4 Formation In The Golden Horse-Duck River Region Of Western Sichuan Basin

As the last strata of the marine evolution of the Sichuan superimposed basin,the Middle Triassic Leikoupo Formation is one of the main oil and gas bearing strata in western Sichuan basin.The Golden Horse-Duck River Block is in the middle of the Longmen Mountain thrust belt in the western margin of the western Sichuan.At present,only Leikoupo Formation obtained industrial production capacity in this area.Many scholars have studied the marine carbonate reservoirs in the Sichuan Basin,which are mainly concentrated in the areas of Sichuan,Sichuan,and northeastern Sichuan.The degree of knowledge is not enough for the Leikoupo Formation in the middle of Longmen Mountain,and the high quality reservoirs controlling factors are not clear.In order to strengthen this research,based on collecting the data of the predecessors and understanding the geological background of the research area,mainly through the core and thin observation,the use of core physical data,mercury information,from the petrologic characteristics,physical characteristics of reservoirs,the types of reservoirs space,the pore structure feature,and so on,this paper is designed to research the characteristics of reservoirs about Leikoupo Formation-4,also by means of thin film identification,logging data,cathodoluminescence analysis,isotope determination,X-ray diffraction,to analyze the sedimentary environment,diagenesis and tectonism of the Leikoupo Formation,and to clarify the reservoir controlling factors of the Middle Triassic Lekoupo Formation in the Golden Horse-Duck River block,so as to provide a good basis for the oil and gas exploration and development smoothly for the later research area and its surrounding areas,but also for the relevant oil and gas reservoir evaluation work and engineering research to lay the foundation.The Leikoupo Formation-4 can be divided into three sub-sectionsincluding upper,middle and lower.The reservoir segment is mainly distributed in the upper section of the four sections of the mine,that is,the target segment of this paper.On the upper section of The Leikoupo Formation-4,there are mainly dolomite,limy dolomite,dolomite limestone,limestone,et al.,in the tidal flat of restricted platform.The dolomitic flat and limy dolomitic flat provide a material basis for the extensive development of the reservoir.The lower reservoir section of the Leikoupo Formation-4 is better than that of the upper reservoir,and its pore structure is complex,and the pore is mainly composed of medium pore and throat.Based on the physical data of the core,the mercury intrusion data and the classification criteria of the carbonate rocks in Sichuan Basin,the reservoirs in the study area are divided into four categories,and the Leikoupo Formation deposited mostly fromthe reservoirs with the types of ? and ?.In the long diagenetic period,compaction,pressure dissolving,cementation and filling make the primary pores of carbonate rocks suffer or even disappear,while dolomitization,dissolution,rupture,dolomitization,et al.,provide good reservoir space such as dissolution,intergranular,cave and so on for the reservoirs.Especially the dolomitization and dissolution are more obvious to improve the reservoir space.The effect of tectonics on the reservoir is mainly manifested in the fact that it can also provide important oil and gas permeation channels and some reservoir space.Therefore,the controlling factors influencing the reservoir development in the Leikoupo Formation-4of the research area include sedimentation,diagenesis and tectonism.