The Reservoir Geological Characteristic Of Chang4+5、Chang6Reservior In Yuan214Region

As a large-scale Triassic reservoir, exploited by Eighth Factory, Chang4+5and Chang6reservoir of Yuan214area in Jiyuan oil field has been experimentally exploited by adopting skewed nine-spot pattern since2005, which shows fruitful and high-output. However, certain problems have been emerging as exploitation. Based on core observing and description, analyzing data of logging, oil testing, sample testing, this paper studies the geologic feature including sedimentary and sand distribution of Chang4+5and Chang6reservoir, clarifies the macroscopic and microscopic anisotropy of low-permeability sand reservoir in Yuan214area, analyzes its reservoir characteristics and main controlling factors. Finally, this paper evaluates the reserves of target area in order to provide reasonable development program for further exploitation.Research shows that:Chang4+5and Chang6reservoirs can be subdivided into four single layers as Chang4+521,Chang4+522,Chang611,Chang612;Chang4+522and Chang612are the main layers of target area. Sedimentary research proves that the underwater distributary channel and interdistributary bay are the main microfacies of target reservoir, the sand distribution of which is stripped and schistose, the next microfacies is mouth bar;The rock type of research area is arkose and lithic feldspar sandstone, feldspar lithic sandstone takes second place, litharenite can be found occasionally;Residual intergranular pore takes dominating place of primary pore, and the next is dissolved pore; Each single layer of target reservoir has server in-layer inter-layer and plane heterogeneity;Lithologic deposit is the main reservoir type, and is dominated by the space distribution of channel-sand.Sedimentary sand in underwater distributary channel of delta front is the favorable area of hydrocarbon deposit, mudstone in interdistributary bay can be lateral harrier of hydrocarbon deposit, local structure spot and small nose-shaped uplift have certain controlling effects to reservoir.Reserves computation studies in this paper shows that geological reserves varies as the oil-bearing area,effective thickness and porosity.