Quantitative Description of the Braided River Delta Sedimentary Facies of the Oficina Formation in MPE-3 Block of the Orinoco Heavy Oil Belt

Key words: 
• Orinoco heavy oil belt /
• Oficina Formation /
• braided river delta sedimentary facies /
• quantitative characterization /
• well seismic combination /
• modern sedimentary analogy /
• empirical formula

Abstract: Quantitative description of braided river delta sedimentary facies of the Oficina Formation in MPE-3 block of the Orinoco heavy oil belt in Venezuela Basin is difficult, which is the key geological factor restricting the efficient development of horizontal wells in this block. Based on the study of regional sedimentary background, it shows that the braided river delta deposits dominates this area which is determined by core description and analysis of laboratory data,mainly developing the subfacies of braided river delta plain and delta front and microfacies such as the mid-channel bar, composite mid-channel bar, braided channel, splay/overflow, flood plain, underwater distributary channel, interdistributary bay, sand sheet and tidal sand bar. Quantitative characterization of major sedimentary microfacies in the study area has been achieved by using three methods:seismic and logging data, analogy of modern sedimentary surveys and empirical formulas. The results suggest that the width of braided channel ranges from 1 km to 5 km, and the width of underwater distributary channel is about 1 km. Empirical formulas between the width and length of the heart beach, the width of the heart beach and the braided channel, the width and depth of the single channel of the underwater distributary channel are established, and the evolution law of the braided river delta during the deposition of the Oficina Formation is further clarified. The research results provide an important geological basis for improving the recovery degree of super heavy oil reservoirs in the study area.