Abstract:

On the basis of the comprehensive application of physical properties, production test, oil testing data, mercury injection data and well log geological interpretation, and by applying distribution function curve method, production test method, oil testing method, irreducible water saturation method, and the lowest effective pore throat radius method, we define the physical property lower limit. Also, we analyzed the controlling factors of the effective reservoir from sedimentary facies, sand thickness, diagenetic evolution, rock components and formation pressure. Our results demonstrate that the main controlling factors are sedimentary facies and sand thickness. Distributary channel facies of braided delta are most effective reservoir development areas, while the least effective reservoir development area is gravity flow environment. Porosity and permeability difference increased with the increasing of particle size in the same diagenetic stage. Also, the higher content of quartz and feldspar, the higher porosity and permeability difference and higher feldspar content, the higher porosity and permeability difference in secondary pore belt. There was positive correlation between overpressure and reservoir effectiveness, but overpressure phenomenon is not developed in the Liushagang Formation and the overall impact is less important.

Key words:  , Beibuwan basin；Weixinan Depression；effective reservoir；physical property lower limit；control factors