A Study On High-resolutin Sequence Stratigraphy In Daan Area Along The River And Rule Of Hydrocarbon Accumulations

Taking sedimentology theories and high-resolution sequence stratigraphy theories as guidance, this study comprehensively used full and accurate well core, well drilling, well logging and the 3-D seismic data, and analyzed depositional dynamic response characteristics of different grades base level cycle. By the study, Putaohua oil layer of Daan area along Songhua river is divided into one long-term base-level ascending cycle, one medium-term base level cycle, nine short-term base level cycles and several short-term cyclical sequences, established high-resolution sequence stratigraphic framework of single sand-body in Putaohua oil layer of Daan area along Songhua river, and summarized a set of high-resolution sequence stratigraphic correlative method of shallow-water delta.Within the regional sedimentology theories and detrital heavy-mineral analysis of the basin, direction of sedimentary source is analyzed. The study area is presented which is influenced by the northwest Yingtai water system and the northeast branching river system of north water system, and sedimentary source from northwest water system mainly deposition in Daanbei oilfield and Daan oilfield while north source in Xinzhan oilfield and Nanshanwan oilfield. It is proved that shallow-water delta in Putaohua oil layer consists of prodelta subface at the top and delta frontier subface in the other, after the research of short-term cycle sedimentary microfacies, sedimentary microfacies vertical evolution and plane distribution characteristics under the control of high-resolution sequence stratigraphic framework. It is realized that narrow framework of this delta system is (submerged) distributary channel sandbodies and lacustrine fluvial-dominated sheet sandstones bar. On the vertical plane, during the cycle of slow water-regression and fast water-transgression of Putaohua oil layer, the biggest pried of water-regression occurred in SSC5 when the best reservoir sediment. On the plane, sedimentary facies of Putaohua oil layer in the study area extends into the NE-SW and NW-SE trending.The development level of sand in the north is better than that in the south while west is better than east.Based on the detailed anatomy under dense well pattern condition, sedimentary mode of Putaohua oil layer is established. Shallow lacustrine fluvial-dominated delta Inner front is mode of fluvial-dominated sheet sand; outer front is mode of outer sheet bar tide-dominated sheet sand; prodelta is mode of Prodelta mud.The research on reservoir rocks characteristics, pore-throat structure, physical structure and diagenesis is operated to determine the influence factor of reservoir physical property. Through the analysis, it could be certain such as reservoir rock type, reservoir space type, diagenetic stage, compactness and the relationship among the sedimentary facies, diagenesisand reservoir physical property. The result shows that reservoir physical property is decided by common action of sedimentation, mechanical compaction and corrorsion while sedimentation play the major role among them. Microscopically> sedimentation control the original composition and structure of the reservoir rocks. Macroscopically, sedimentation dominates the distribution and effects the type and strength of diagenesis during the late evolution. Diagenesis is important for its influence on evolution of reservoir space and reservoir pore-throat structure characteristics, what's more, it decide the magnitude of the reservoir physical property finally.With the study above and hydrocarbon accumulation theory, giving full consideration to construction, sediment, grooming system, accumulation power and other factors, hydrocarbon accumulation model is studies on the base of detailed anatomy under dense well pattern condition. It is conclusive that main reservoir types are fault-lithologic reservoir, lithologic reservoir and fault reservoir after the study on accumulation condition reservoir type and main controlling accumulation factor. The hydrocarbon distribution is control by fault system and sedimentation.It is predicted that favorable hydrocarbon accumulation zones is wings of Daan nose structure and Nanshanwan slope, for the source control fault,distributary distribution channel and sheet sandstone bar there. Based on the guidance above,9 favorable traps are predicted, and 10 exploration wells or evaluation wells are deployed.