Study On Characteristics And Distribution Of Reef Flat Reservoirs Of Lower Ordovician In Qianzhong Uplift And Its Adjacent Areas

In view of problems on characteristics and distribution of reef flat reservoirs of lower Ordovician in Qianzhong uplift and its adjacent aeras, this dissertation researches on sedimentary facies, characteristics and distribution of reservoirs, by means of reservoir sedimentology of carbonate rocks, reservoir geology, petroleum geology and so on and based on materials such as field outcrops, ordinary and cast thin sections and physical properties. Then, we analyze the control factors on reservoirs, including sedimentary facies, diagenesis and tectonism. Lastly, we evaluate and prognose the potential reservoirs.Firstly, the aimed formation was researched, lithofacies paleography distributions were defined, and sedimentary models were established by means of field outcrops and rock thin sections. The reef flat bodies distribute in Honghuayuan group and Tongzi group, including sponge reefs, bioclast banks, arene banks, ooid banks and organic banks, especially most developed in Honghuayuan group.Secondly, diagenesis, physical characteristics, petrology characteristics, accumulating vacuity types and distribution of reservoirs were studied on base of sedimentary facies researches, referring to thin sections.Lastly, main factors control reservoirs were analyzed. Sedimentation is the base, it determines the rock types and distribution scope; Diagenesis is critical, it controls pore evolution and distribution of beneficial reservoirs; Tectonics is important to improve the ability of porosity and permeability of reservoirs. Reservoirs were classified and evaluated, and distribution of potential reef flat reservoirs was indicated. Reservoirs of reef flat in Qianzhong uplift and its adjacent areas are mostly classified into gradeâ…¢and little gradeâ… andâ…¡.According to the concrete geological background, principles of hydrocarbon potential evaluation are proposed, and Qianzhong uplift and its adjacent areas are divided into three hydrocarbon potential districts: beneficial potential district, moderate potential district and unbeneficial potential district. Beneficial potential district distributes at the area around huangping~kaili~duyun~huishui in south Guizhou depression; Moderate potential district distributes at the area around yuqing~shiqian~yinjiang in Wuling depression; and unbeneficial potential district distributes at the area around daozhen~zhenan in north Guizhou depression.