Abstract:

Dengying Formation of Sinian is the important gas-bearing strata in the eastern Sichuan Basin. There is important guiding significance for finding the distribution of favorable reservoir by the analysis of the reservoir characteristics and their controlling factors in the eastern Sichuan Basin. The combined macroscopic and microscopic methods are adopted for this research on Sinian Dengying Formation in the eastern Sichuan Basin. Based on the lithology characteristics, the scanning electron microscope, the cathode luminescence and some other experimental analyses, some outcrops which are taken from the outcrops and the drilling cores of Dengying Formation are studied for this paper in the eastern Sichuan Basin. The dolomite reservoir of Dengying Formation is studied in the research. The types of the dolomite reservoir formed on the 2nd Member and the 4th Member are mainly the algae dolomite, grained dolomite, powder to fine-grained dolomite and the karst breccia formed in two phase of the weathering crust of 0 to 200 m. The algae dolomite is the main reservoir rock types in the study area among them. The types of reservoir space are very complex, in which primary pore space didnt be found, and there are mainly secondary holes, seams and holes. The types of reservoir space are mainly intergranular dissolved pore, intragranular dissolved pore, secondary intergranular pores and structural fractures and caves, etc, and the intergranular dissolved pore is the main pore types among them in the study area. The development of the dolomite reservoir is mainly controlled by sedimentary environment, diagenesis and tectonic action, etc. The main factor influencing the 2nd Members reservoir development is sedimentary environment, and another important factor which stores the raw holes is the dissolution diagenetic epigenesis, especially the ancient karstification is the main factor for the 4th Member’s reservoir development. Recrystallization and dolomitization play a positive role for the formation and preservation of pore, while the cementation is the main factors of reservoir damage lower’s porosity. In addition, Tongwan Movement formed the early group of the large hole, and the later tectonic movement established the particularly complex pore-cavefracture system in the research area.

Key words: Dengying Formation, dolomite, reservoir, controlling factor, eastern Sichuan