OIL AND GAS EXPLORATION FIELD IN RIFT STRATUM IN THE SOUTH OF THE SONGLIAO BASIN

There are many rifts and depressions with rich oil and gas in the south of the Songliao Basin.Shiwu Depression and Changling Rift(depression) are the geological units with rich oil and gas,and a number of small and medium oil-gas fields had been discovered.Research suggested that there are two types of rift stratum and depression stratum petroleum systems.Oil-gas reservoir of rift stratum is mainly controlled by the efficient volcanic reservoir and low porosity-permeability of the reservoir.Structural reservoir of volcanic rocks and low-permeability sandstone reservoirs were formed composite with structural.Depression reservoir was controlled by sand distribution of delta front,forming structure-lithology reservoir at a favorable context.Studies suggest that exploration fields of rift stratum include: volcanic rocks reservoir,stratigraphic unconformity reservoir,steep lithology reservoir and metamorphic rock reservoir of bedrock.