Detailed Research Of Sequence Stratigraphy And Sedimentary Facies For Putaohua Formation Of The Middle Gulong Depression In Songliao Basin

Serving the exploration of lithology reservoirs for Putaohua Formation of middle Gulong Depression in north Songliao Basin, based on the theories of sequence stratigraphy, sedimentology and petroleum geology, with integrated data from drilling, log, seism, core and testing, the author systematically researched the characteristics of sequence stratigraphy, sedimentary setting, slope belt and reservoir distributing for Putaohua Formation of middle Gulong Depression. A detailed stratigraphy framework was established, and so was a sequence-sedimentary model. The types of sedimentary setting and the composing features of sedimentary facies were clarified, and then the evolution and distributing rules of sedimentary facies were discovered. The control of slope belt to sedimentary facies was discussed, too. Lastly, the author synthetically analyzed the dominant factors of reservoir forming, and forecasted the distribution of probable stratigraphy-lithology traps. The accomplishment of the article was hoped to give guidance to the exploration breakthrough in work area.The following are main productions:The Putaohua Formation in work area, probably a third-order sequence, could be divided into three parasequence sets, and they are separately corresponding with P13, P12 and P11 member. They could be further divided into eight parasequences. Besides, the fine sequence stratigraphy framework was set up for Putaohua Formation in work area, and the stratum developing characteristics and distributing rules of parasequences from different evolution stages were summarized.In the detailed sequence stratigraphy framework, with every parasequence as mapping unit, the sedimentary facies maps of different members were authorized for Putaohua Formation in work area, and the evolution rules of sedimentary settings in different stage were discovered. Influenced by continental clastic sources from westward Yingtai and northward Keshan-Qingshugang, there were mainly developed lacustrine-delta sedimentary system and lacustrine sedimentary system in work area.Systematical studied plane-distributing characters of slope belts in different stage, and analyzed the control of slope belt to the developing sedimentary facies of different parasequence.There are several types of reservoir in work area, such as fault-lithology, anticline-lithology, sandstone lens lithology and up-incline cusp lithology reservoir, and so on. Dominant factors of reservoir forming include: oil-generating intensity which controls the distributing scope, structural fracture which controls the migration and collection, and micro-facies types which control the distribution of oil-bearing sand bodies. Based on the studies of sedimentary facies, sequence stratigraphy and reservoir forming, the prospect areas Putaohua Formation in work area were pointed out.