The Sequence Stratigraphy, Sedimentary Facies And Reservoir Research In Jialingjiang Formation In Chishui-Qijiang Region, Southeast Of Sichuan

Several favorable traps such as Tiantangba, Simianshan, Jiaozishan and some gas pools like Wanglong, Taihe, Baoyuan in Chishui-Qijiang Region, Southeast of Sichuan have revealed good prospects about natural gas exploration and development of Triassic Jialingjiang Formation in the southeast of Sichuan. Therefore, the author comprehensive and accurately evaluates the reservoir Jialing Formation and accurately grasps the development of reservoir distribution law, which is important to further exploration and development of Jialingjiang Formation in this area.According to the comprehensive research about the fegional Report Search, the observation of outcrop, logging, well logging, core and thin slice etc., the author establishes the sequence and high frequency sequence framework of Jialingjiang Formation and detailly describes the distribution of sedimentary facies and reservoir within the sequence and high frequency sequence framework, and then further masters the law of the sedimentary facies evolution and reservoir development within the sequence framework. On the top of that, the author reach the target of the reservoir comprehensive evaluation. The major outcome is following.1. The Jialingjaing Formation is divided into two 3rd-order sequences, six 4th-order sequences and fifteen 5th-order sequences. And the 3rd-order sequence is type II sequence, the sequence structure patterns are type H sequence. In the research of the high frequency sequence, the author identifies 33 high frequency sequences.2. Establishing the comparison of the 3rd-order sequence and high frequency sequence framework, the author points that the major control factor of the sequence generation in Jialingjiang Formation is sea-level change and climate change, and the correlation of the tectonic uplift and source supply is lower.3. According to the sedimentary facies identification mark, the study area is divided into several subfacies such as the wide open, the platform within the beach, half-restricted lagoon, restricted lagoon and restricted sets Ping etc and 23 microfacies. And the author proposes the sedimentary model within the sequence framework. Finally the author detailly describes the distribution of sedimentary facies, using the system tract in 3rd-order sequence, 4th- order sequence and key 5th-order sequence as isochronal unit.4. The author identifies the reservoir space of Jialingjiang Formation reservoir is made up of intergranular dissolution pores, dissolution pores, mold hole, intercrystalline pores, intergranular dissolution pores, Plaster mold hole and cracks etc., especially the intergranular dissolution pores is important. According to the reservoir causes, the reservoir is divided into beach erosion pore type, limitations table dissolution pore type, paste dissolved type and fractured porous.type.5. The research shows that the diagenesis of Jialingjaing Formation reservoir includes cementation, dolomitization, creaming to creaming, compaction pressure solution, dissolution, filling, fracturing, etc. On the basis of that, the author builds up the diagenesis succession, analysis the evolution of the reservoir space, and indicates the contemporaneous dissolution of atmospheric water is the main factor for the reservoir development.6. Studying the relationship of the sequence and reservoir, the author believe that the longitudinal and lateral distribution of reservoir development is controlled by 3rd-order sequence and high frequency sequence. The reservoirs mainly developed in the high system tract, whose generation is controlled by the cycle evolution of 5th-order sequence. And the reservoir in arid climate and humid climate presents the different modes, which causes that the reservoir in 5th-order develop in different position.7. According to the research of the reservoir physical properties, the author think that the physical properties of the reservoir is low porosity and low permeability, and the reservoir that permeability is good match with porosity is dissolution porosity type. According to the reservoir classification and evaluation criteria, the author believe that the reservoir which developed in Chishui-Qijiang area in southeast of Sichuan belongs Class III reservoir.