Exploration of the Lower Permeability Reservoir in Sanzhao Area of Songliao Basin: ABSTRACT

Abstract

Sanzhao area is an independent petroleum generation-migration-accumulation unit that concentrates in the Sanzhao sag, a large sag in the central depression of Songliao basin. The oil generated from the Lower Cretaceous Qingshankou Formation migrated into Fuyu and Yangdachengzi reservoirs in Members 3 and 4 of the Quantou Formation, with the overpressure of the source bed driving fluids through dense fault pathways. Fuyu and Yangdachengzi reserviors are formed by areally-extensive, fluviodeltaic thin interbedded sandstones. Most of the oil pools in Sanzhao area are in low-permeability lithologies. In order to prospect for these lower permeability reservoirs, first we set evaluation and oil/gas reservoir evaluation. On the basis of the composite study of petroleum geology, the low-permeability feature of Fuyu and Yangdachengzi reservoirs has been further understood. Secondly, we have developed a series of exploration methods and techniques, including high-resolution seismic exploration, oil testing and fracturing, and techniques for protecting oil reservoirs. Due to breakthrough in understanding of petroleum geology and the development of composite exploration techniques, the low-permeability reservoirs of Sanzhao area have liberated abundant reservers. A large, low-permeability oil province with reserves of more than 10x10[sup 8] has been proven.