Exploration of the Lower Permeability Reservoir in Sanzhao Area of Songliao Basin
Sanzhao area is an independent petroleum generation-migration-accumulation unit that concentrates in the Sanzhao sag, a large sag in the central expression 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 reservoirs are formed by areally-extensive, fluviodeltaic thin interbedded sandstones. Most of the oil pools in Sanzhou area are in low-permeability lithologies.
In order to prospect for these lower permeability reservoirs, first we set up three scientific exploration evaluation programs: basin evaluation, trap 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 breakthroughs in understanding of petroleum geology and the development of composite exploration techniques, the low-permeability reservoirs of Sanzhao area have liberated abundant reserves. A large, low-permeability oil province with reserves of more than 10×108 has been proven.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California