Depositional Facies Analysis on Tight Reservoir of Lucaogou Formation in Jimsar Sag, Junggar Basin

Key words: 
• Junggar Basin /
• Jimusaer sag /
• Lucaogou Formation /
• salified-lake /
• sedimentary facies /
• tight oil

Abstract: Using cores, thin section, log and well log data, based on the identification of every base types and characteristics of the cycle interface, the Permian Lucaogou Formation strata in Jimsar sag are divided into 1 long-term cycles, 6 medium-term cycles and 44 short-term cycles, the high resolution sequence stratigraphy correlation framework is established. On the basis of summarizing the geochemistry, lithology, sedimentary structure and electrical characteristics, comprehensive analysis of fossils and logging data to identify the sedimentary facies marks, single well, well connected and plane sedimentary facies analysis, the Permian Lucaogou Formation strata are mainly salified-lake facies, locally delta facies deposit, with the complex lithology formed by mechanical deposition, chemical deposition, and the deposition of fine clastic rocks, mud and carbonate rocks which are deposited under the influence of the deposition. Lucaogou Formation developed two tight oil body sweet spot, the upper body is a kind of salty lacustrine carbonate rocks, the types of micro facies in shallow lake dam; The inferior dessert is mainly based on the delta front to the former delta subfacies. Micro facies type is sheet sand and far sand dam. At the same time, the advantage of horizontal continuous change of reservoir in the area of the study area and the level of the well is to be revealed by the reservoir, control of planar micro facies boundary in tight oil reservoir, thus more accurately reflect the plane distribution characteristics of tight oil reservoir. Research shows that the quality of Lucaogou Formation near to the sweet spot is beach bar microfacies mainly developed in the center of the sag at low uplift.