Reservoirs Characteristics And Distribution Of Sinian Dengying Formation In Southeast Sichuan

In view of problems on characteristics and distribution of Dengying Formation reservoirs, this dissertation researches on sedimentary facies characteristics, reservoir rock characteristics, reservoir physical characteristics and reservoir oil and gas bearing by means of reservoir geology, reservoir sedimentology of carbonate rocks, petroleum geology. This is based on previous studies, ordinary and cast thin sections and test analysis on samples from field outcrops combined with field and indoor information, macro and micro observation. Finally we made comprehensive analysis on Dengying Formation reservoirs in southeast area and predicted potential reservoirs.(1) Sedimentary facies belt of Dengying Formation presents NE– SW, and develops a broad dolomites with a stable thickness. The deposition pattern is relatively simple, only including platform face and shallows. tidal-flat facies includes tidal flat, supratidal flat, tidal flat .(2) Rock types is complex and diverse in Dengying Formation reservoirs, which is characterized as algal-laminated dolomite, algal-dolarenite, botryoid dolomite and crystalline particle dolomite. There are mainly pores, intergranular dissolution pores, intergranular pore, solution openings and fractures in different size, which developed some intergranular dissolution pores with poor connectivity. Pressolution, cataclasis and dissolution made for diagenesis of reservoir space development, but cementation and silicification acted as saboteurs.(3) The reservoir physical characteristics of Linyijing, Renhuaidawan and Jinshayankong are the best, and Zunyisonglin and Xishuidayan are the comparative better but Dingshanyijing is the worst. Linyijing has a relatively good permeablility, thick carst layer together with a mass of fractures affected by Tongwan movement, so there reservoir physical characteristics is obviously better than Dingshanyijing's; It had development of a set of shallow in platform, including dolarenite, oolitic dolomite and botryoid dolomite to form good reservoirs which is affected by corrosion during cyclical decline in sea level and a mass of vugs caused by karstification and denudation during epidiagenetic stage.(4) It developed a mass of suture lines, cracks, caves, intercrystalline pores, intercrystalline dissolved pores, intergranular dissolved pores and intragranular dissolved pores. There are two stages of oil and gas accumulation, one is formed from Ordovician to Silurian, the other is from Permian to Jurassic. But Yanshan movement and Himalayan movement play a huge role in the destruction to oil and gas accumulation, and then the research area uplifted in a vast scale to form complex fault and high-angle fracture system resulting in the complete destruction of the ancient gas reservoir.(5) There is not appearⅠandⅡreservoir bed, its adjacent areas are mostly classified into gradeⅢandⅣ. One Beneficial potential district distributes at the area around renhuai-dawan, we need to make sure that the platform is extended to overlay area, this is the focus of further exploration. According to the concrete geological background of lin 1 well and dingshan 1 well,lin 1 well is better than dingshan 1 well, so the other Beneficial potential district distributes northwest wing of lin tan chang upfold where is high covered structure and away from the surface of the ground has been cut through the area.