Characteristics Of Cambrian And Ordovician Dolomite Reservoirs In Tazhong Area, Tarim Basin

Carbonate rocks can be very good quality oil and gas reservoirs which are important to us. Around the world, limestone and dolomite contain more than half the oil and gas resources. Due to its characteristics, dolomite reservoirs are one of the world's most important reservoirs. Cambrian and Ordovician dolomite reservoirs are well developed in Tazhong Area of Tarim Basin, which are important reservoirs for us. There are many different kinds of dolomite reservoirs, and the exploration is complex too, so it is important for us to do research on diagenesis and dolomitization, and to observe the dolomite reservoir space.Firstly, after the study of abundant of data and papers, I constructed a basic knowledge system about the carbonate reservoirs in Tazhong area. Based on the multiple theories, combining with the field work and experiments, I do research on the Cambrian and Ordovician dolomite reservoirs.According to structural features and special tectonics, Cambrian and Ordovician dolomite in Tazhong Area can be divided into silt dolomite, fine dolomite, medium dolomite, coarse dolomite, porphyritic dolomite, laminated dolomite and karst breccias dolomite. The proposed dolomitization mechanism of Cambrian and Ordovician dolomite in Tazhong Area is sabkha evaporation dolomitization, seepage-reflux dolomitization, blend water dolomitization, burial dolomitization, and hydrothermal dolomitization.Fractures and vogues are well developed in Cambrian and Ordovician dolomite in Tazhong Area. Some of them are filled by lime, organic matters or gypsum; the others are dissolved furtherly, forming fracture-cavity systems. During the multiple tectonic movements, Cambrian and Ordovician dolomite in Tazhong Area developed multiple tectonic fractures, which highly increased the quality of dolomite reservoirs.Based on the out crop analysis and core observation, studying on well logging and seismic sections, according to plenty of test results, we do research on the features of dolomite reservoir in Tazhong area. The characteristics and distribution of sedimentary facies are controlled by the evolution and structure of carbonate platform, which will decide the distribution and development of the carbonate reservoirs. According to the synthesis analysis on facies condition, dolomitization, dolomite types, tectonic fracture and karstification of Cambrian and Ordovician dolomite in Tazhong Area, we made a conclusion that Cambrian and Ordovician dolomite in Tazhong Area has the potential to be good quality reservoirs.