Sedimentary Evolution And Hydrocarbon Distribution In The Middle-shallow Layer In The South Of Songliao Basin

There are abundant hydrocarbon resources in the south of Songliao Basin. The proven reserves mainly concentrate in the middle-shallow layer of the third member of Quantou formation to Nenjiang formation at present. This thesis is on the instruction of reservoir sedimentology, petroleum geology and hydrocarbon accumulation dynamics. Setting up the rearch of sedimentary system and classify of profitable facies belt in middle-shallow layer in the south of Songliao Basin using geology, geochemistry, geophysics and analyzed assay datum. To establish the sedimentary facies type and it's distribution pattern, and sedimentary evolution mode. Evaluate each facies belts of different sedimentary facies comprehensively. Predict the range of profitability combine with the master factors of hydrocarbon accumulation and accumulation mode of Middle-shallow layer in the south of Songliao Basin. So obtain the object to uncover the new region of exploration activity.According to the detailed observation and description of core, progress the synthesized analysis by combinbing the well logging, data of areal geology and all kinds of analyzed assay datum, assured the distribution regular pattern of sedimentary system in this area. Braided river, meandering river, terminal fan, braided river fan, delta, shallow delta, braided delta and beach bar sedimentation types are identified, and bring forward the new sedimentary mode and Sedimentary evolution regular. The climate is heat and arid in the third member of Quantou formation, and river-terminal fan sedimentary system develops in this period. There is no unitary water catchment center in the fourth member of Quantou formation, river-terminal fan sediment is the major sedimentation type, braided river fan-meandering river develops in the northwest of research area. Delta and shallow delta develops in the Qingshankou formation. The sand body distributes in the western area, the provenance come from the west, southwest and south of the research area, the east is muddy sediment. The braided delta develops in the northwestern Yingtai-Baicheng water system in Yaojia formation,and shallow delta develops in the southwestern Tongyu-Baokang water system and southern Changchun water system. The shore-shallow lake and hemi-deep-deep lake develop in the first and second member of Nenjiang formation, and thin bed beach sands distribute fragmentarily. The water body becomes shallow and the lake basin reduces from the third member of Nenjiang formation to the fifth member of Nenjiang formation, delta develops from the north provenance, and the constant provenance absent from the south provenance.The reservoir types in the middle-shallow layer in the south of Songliao Basin are studied based on the analytical data from the laboratory, and the relation between facies belts and reservoir characters of different sedimentary facies are analyzed. The reservoir of different facies belt are evaluated, and profitable facies belts are defined. The result shows that the reservoir quality of underwater distributary channel and channel mouth bar of delta front, distributary channel of terminal fan, braided channel of middle braided river fan and the channel of river facies are well. The reservoir quality of bank of river facies, distributary channel of shallow delta, distal bar and distal channel of delta front, sand sheet, overbank of terminal fan take second place. The reservoir quality of flood plain of river facies, mud flat and distal basin of terminal fan, predelta and interchannel area are bad.Take the point of hydrocarbon accumulation association to study the planar and sectional distribution pattern of petroleum reservoir. The relation between petroleum distribution and sources rocks distribution, profitable facies belt, petroleum dredge system and so on. Summary the regularity recognition of petroleum distribution. The petroleum distribution in the middle-shallow layer in the south of Songliao Basin is under the control of sources rocks distribution, accumulate facies belt, profitable association of source rock, reservoir and cap, effective trapping and fault and so on. The hydrocarbon accumulation mechanism is analyzed in different belt of the middle-shallow layer in the south of Songliao Basin on the base of research of hydrocarbon accumulation and petroleum distribution, and predict the range of profitability.