The Study On The Sequence,the Sedimentary Facies Of The Ordovician Carbonate Rocks In The North Of The Tarim Basin

The thesis put the Ordovician carbonatite in north Tarim as the research object. Using sequence stratigraphy, seismic stratigraphy and lithology paleogeographic. Combined with core observation, microscopic thin section identification, drilling, logging and seismic methods to synthetically analyze. Carried out the reservoir research with the area's Ordovician sequence, sedimentary facies and carbonate.Combined logging and seismic, the Ordovician in the northern area of the Tarim Basin is divided into two 2 order sequences and three 10 order sequences. The Penglaiba formation is divided to two tertiary sequences(SQ1, SQ2) and Yingshan formation is divided to two third-order sequences(SQ3, SQ4), Yijianfang formation has one third-order sequence group(SQ5), Qiaerbake formation one sequence(SQ6) and Lianglitage formation is divided to two third-order sequences(SQ7, SQ8), Sangtamu formation is divided to two third-order sequences(SQ9, SQ10). And the three level sequence framework of drilling section and seismic profile is established.Analysed core, thin sections and well seismic, divided the area in the Ordovician into the platform, slope and basin sedimentary facies. Platform facies are divided into restricted platform, open platform, platform margin facies. Restricted platform can be divided into tidal flat and intraplatform shoal; Open platform can be divided into the beach interact sea and intraplatform shoal; Platform margin can be divided into the beach interact sea, platform-margin shoal and platform margin reef.On the division of sedimentary facies and the study of the sequence, the sedimentary facies distribution of the three order sequence framework is established. In the horizontal, the middle, low Ordovician developed the platform, the platform margin, the slope and the basin from the west to east. The upper Ordovician, the northeast of northern Tarim was mainly shallow ramp deposits, change gradually into- deep slope and basin facies into the southwest; West and north in northern Tarim developed typical carbonate platform facies zone and the change gradually to slope and basin phase into south.Through the research study of sedimentary facies and sequence stratigraphy in the area, established the plane distributive maps of Ordovician sedimentary facies, dynamically revealed the evolution of sedimentary facies in the studied area. In Penglaiba, Yingshan formations, from west to east developed carbonate platform facies, platform margin facies, slope and basin facies; Yijianfang formation developed platform margin, slope and basin around the terrace on both sides; open platform facies evolved to submerged platform facies in Qiaerbake formation, platform in northern evolved into horseshoe-shaped platform and the structure of two basin in southern in Lianglitage formation. On the understanding of the distribution of sedimentary facies belts, and combining with the previous studies on the paleo tectonic, sedimentary paleo geomorphology and sea level changes, the paper summarized 3 types of sedimentary evolution of the Ordovician in the area.Through the analysis of core, thin sections and single well section, realized that the Ordovician in north tarim basin developed dissolution pores, solution pores, caves and cracks, reservoir can be divided into three types: fracture-pore type, seam pore-cave and cave reservoirs.By statistics of the reservoir in single-well profile, met the relationship between the sequence, reservoirs and sedimentary facies, and compiled the framework of the development of reservoir under the sequence, concluded that the karstification related in sequence interface and tectonic movement is the main factors to control the development and distribution of carbonate reservoir.Summaried the law of development and forming mechanism of reservoir, pointed out that the the most favorable facies belt of Ordovician reservoir distributed in north area is the Tahe area and YingMaiLi region where within the boundaries of ordovician pinch-out line with Lianglitage formation, Yijianfang formation; Relatively favorable reservoir facies belt distributed in YaKeLa areas where out the ordovician pinch-out line, with Penglaiba formation's pointed out the line.