Sedimentary And Reservoir Assessment Of Shan1 And HE8 Reservoirs In The East Ⅱ Part Of Sulige Gas Field

Sulige Gas Field in Ordos basin is characterized by compact sandstone, low-porosity, low-permeability and strong-heterogeneity that becoming the main limitative factors of explora-tion and exploitation of natural gas. For the sake of forecasting the distribution and feature of the clastic rock reservoirs, this paper studied the microfacies distribution of the objective zone in the east II part of Sulige Gas Field and evaluate the reservoir. The objective zone is Shanl member of Shanxi Formation and He8 member of lower Shihezi Formation. On the basis of predecessors study, the conclusion is directed by sedimentology, reservoir geology and gas development, meanwhile using core survey, various analyses and tests and well loggi-ng data. The conclusions are as follows:①In the studied area during the period of Shanl and He8 deposition, the braid river is the main sedimentary facies, and meandering river plays the second role. The main microfacies are braided channel, channel bar, point bar and channel fill.②Compaction, cementation and metasomatism of Shanl and He8 reservoir cause the porosity decline; Corrosion improve the pore structure.③Shanl and He8 reservoir is low porosity, low permeability and strong-heterogeneity; the main pore types of reservoirs are solution pores of debris and intracrystalline pore; the reservoir pore-throat characterized by mini pore throat, poor sorting, poor heterogeneity and poor connectivity; the physical property of He8 reservoir is better than Shanl reservoir's physical property④According to physical properties of reser-voirs and parameters of pore structure, reservoirs in this area can be divided into four types, which is dominated by typeⅢand typeⅡ; TypeⅢreservoir distribute most widly, and typeⅠreservoir has very limited distribution; On the whole, the reservoir type of He8 lower subme-mber is the best, Shanl member play the second role and He8 upper submember is the worst; The high-quality reservoirs develop in the channel bar, point bar, braided channel and channel fill microfacies.