Sequence Stratigraphy And Sedimentary System Study In West Clinoform Region Of North Songliao Basin

This study not only applies comprehensively cores, logging, well logging, seismics, analysis assay data and paleontology data, but also adopts the latest theories and technique and methods of sequence stratigraphy, high-resolution stratigraphy, sedimentography, oil-gas geology, geophysics, stratigraphic paleontology and geochemistry, etc. Exerting the predominance of many subjects jointly tackling key problem, The paper profoundly analyses and studies the sequence stratigraphy and sedimentary systems of the middle oil-bearing assemblage in West clinoform region of north Songliao Basin.This research achievements enriches continental facies sequence stratigraphy and lake basin sedimentology. Furthermore, the achievements have important instruction function and reference value for henceforth oil and gas exploration in this region.From the bottom boundary of No.2～3member of Qingshankou Formation to the top boundary of No.1member of Nenjiang Formation Five three-stage sequences and ten four-stage sequences are developed in Work area. Three-stage sequences separately are No.2member of Qingshankou Formation (SQqn2) , No.3member of Qingshankou Formation (SQqn3) , No.1～2member of Yaojia Formation (SQy1-2), No.3member of Yaojia Formation (SQy3), No.1～3member of Nenjiang Formation (SQn1-3). All of the three-stage sequences develop transgressive system tract and high-position system tract. SQqn2 is composed of four-stage sequence c1 and c2. SQqn3 is composed of four-stage sequence c3, c4 and c5. SQy1-2 develops four-stage sequence c6. SQy3 develops four-stage sequence c7. SQn1-3 develops four-stage sequence c8, c9 and c10. Four-stage sequences cl to c6 separately develop transgressive system tract and high-position system tract. C7 mostly develops transgressive system tract and develops high-position system tract in the west edge of work area. C8 mostly develops thick saturated mudstone and develops transgressive system tract sandstone in Fulaerji and its west area. C9 develops low-position system tract sandstone, high-position system tract turbidite and thick saturated mudstone in mostly area, and it develops transgressive system tract and high-position system tract sandstone in Fulaerji and its west area. C10 develops low-position system tract sandstone in mostly area, and it develops transgressive system tract sandstone in Fulaerji and its west area. Three-stage sequence interfaces have ten characters and four-stage sequence interfaces have twelve characters. C5 locates on the top of Qingshankou Formation. C6 locates on the bottom of Yaojia Formation. The distributions of c5 and c6 are the least and mostly distributes in the southeast area. C4 locates on the middle-upside of Qingshankou Formation. C7 locates on the upside of Yaojia Formation. The distributions of c4 and c7 are obvious ampliative. C1, c2 and c3 locate on the middle-underside of Qingshankou Formation. The distributions of c1, c2 and c3 nearly cover West clinoform region. C8,c9 and c10 form Nenjiang Formation.The distributions of c8,c9 and c10 exceed beyond West clinoform region.Each system tract of SQqn2 and those system tracts of four-stage sequences it containing develop lacustrine facies and delta facies. The scale of deltas gradually enlarge upwords. The transgressive system tract of three-stage sequence SQqn3 corresponds to the transgressive system tract and high-position system tract of four-stage sequence c3, and it relatively develops bad deltas and broad lacustrine facies sediments and forms abundant lake bay carbonate sediment terranes. The high-position system tract of SQqn3 corresponds to the transgressive system tract and high-position system tract of four-stage sequence c4 and c5. Its distribution gradually shrinks eastwordly, and delta gradually push eastwordly, and the zone of...