Study On Seismic Stratigraphy Of Jiufotang Formation In Hulihai Subsag

In recent years, oil exploration target has been moved to the edge of the basin, cutting across the waterfront shore and offshore, the hope of exploration targets was deep in these basins, in addition to the shallow marine clastic and carbonate reservoir facies, often included potential deep-water reservoir. Obviously, this marginal basin was lack of a sufficient number of well control, and not allowed to use conventional methods of analysis and mapping underground. Thus, exploration scientists must extract maximum information about the subsurface from seismic reflection profiles. If these basins can not be interpreted, exploration work can only be limited on lack of understanding of the reservoir, source rock and cover to drill structural anomalies. The concept and the technology of seismic stratigraphic interpretation is developed in order to meet this need.By the concept of under depression for oil exploration philosophy in peripheral basins, HuliHai Sag area surrounding was the main target areas for oil and gas exploration. In analysis of tectonic background, the geological conditions around HuliHai Sag was enough to form the lithologic reservoir, the two reservoirs of Q2has been found in the region structural-lithologic reservoir and central subsags was the better places look for lithologic reservoir. In addition, on the base of exploration experience of the Erlian Basin similar depressions, Huli Hai depression trap favorable area of the eastern slope with hydrocarbon migration, a tectonic-lithology or lithologic reservoir geological conditions. In the area Q30well and Q33well have been drilled in the main target Jiufotang which was thick, properties braided river delta front sandstone with good physical, is conducive to the formation of lithologic reservoir slopes context and two wells were seen in good oil and gas shows, the area with the formation of lithologic reservoir of good.The Huli Hai Sag was the lower cretaceous sedimentary thickest and the largest of Qianjiadian depression, north east-north-northeast trending. The work area is located in Huli Hai Sag north, about24.8km, a width of12km, an area of about200km2. Qianjiadian depression, the Huli Hai depression trap Lower Cretaceous time had characteristics of short, sediment thickness, split, vertical and horizontal changes quickly. Early Cretaceous, the area had strong faulting and volcanism. By a large area of volcanic eruptions, of a broad distribution of the Yixian formation volcanic series had formed, and minor lacustrine mudstones main lithology was the thick basic to acidic volcanic and volcaniclastic rocks. The NE-trending fault development formed a rift basin prototype. The sandstone reservoir mainly developed in the Jiufotang,Sahai, and Jiufotang strata was development of the sandstone reservoir.It was aim at depression re-geological evaluation to determine the distribution of effective source rocks of the HuliHai Qianjiadian depression by this project, and found out the HuliHai subsag deposition system Jiufotang and Sahai, reservoir development features and oil-gas, focusing on looking for the structural-lithologic reservoirs and lithologic reservoir proposed exploration targets, evaluation and discovery of new oil and gas blocks. It provided a basis for future research, and exploration. The main technical means was to make full use of the principle of the underlying science of earthquake, interprete seismic data for more geological information, and combine with logs, core data sedimentary facies and effective trap forecast.we have got the following research mainly through the study of the area(1)The HuliHai Sag the main layer segment Jiufotang-Sahai can be divided into five mid-cycle, MSC1, MSC2interim cyclic sequences can be further divided into three short-term cycles.(2)The overall performance was the southwest, surrounded by high tectonic pattern by a series of NNE trending normal faults segmentation, which can be divided into the western fault zone, the central subsags with eastern slope belt.(3)The seismic stratigraphy explained showed that the district developed before messy, pre-bias plot, plot the S-shaped front lens reflection and a series of special reflection structure, and it can create seismic facies and sedimentary facies correspondence by applicating synthetic seismogram calibratio method.(4) MSC1, MSC2interim cyclic sequence developmented three kinds of sand body type. The nearshore subaqueous fan was in west side of sag, fan delta in east,the slump turbidite fan deposition in central part of Sag. In order to carry out MSCl,MSC2plane phase analysis more reliable reflection of the sedimentary facies distribution.(5)MSC2and MSC1sequences identified fault block, lithology, faults-lithologic traps5, and applicated seismic interpretation data, seismic reservoir inversion data to descript and evaluate trap elements and features.(6)On the basis of detailed analysis of success and defeat the main factors, We have summarized the main controlling factors of hydrocarbon accumulation in this area was the reservoir, fault sealing and trap-supporting oil source, and carried out a comprehensive evaluation of geological and queuing on the five found traps to make recommendations to the two exploratory wells.summary, we had important knowledge on structural characteristics and sedimentary characteristics of the HuliHai depression, and predicted the sedimentary facies and effective trap location through the interpretation of the seismic data, combined with logging, core data reasonably.