Sequence Stratigraphy Research And Lithologic-Stratigraphic Trap Prospective Area Prediction In Gentle Slope Of Depression Basin

The paper chose J1s-K1q1 formation in Shinan area, central Jungar basin asresearch object, which was typical gentle slope of depression lake basin andconducted sequence stratigraphic research, depositional facies research and oil poolforming rules research. The aim was to reveal the sequence characteristics and itscontrolling factors, gentle slope depositional system evolution characteristics and oilpools distribution rule, and to direct the lithologic and stratigraphic oil poolsprospective areas.Firstly, dissertation took advantage of abundant 3-D seismic data, core data andlogging data to build the sequence framework in Shinan area, which bears thecharacteristics of gentle slope sequence in depression basin, and summarized itscharacteristics. It was indicated that the sequence. framework has two maincharacteristics. One is that lowstand systems tract (LST) rarely occurs, which is filling inresidual ravine accommodation. The other is that transgressive systems tract (TST)develops thick sands and conglomerate, while highstand systems tract (HST) lacks sand.Based research above, the author further indicated that sequence on gentle slope had fourcontrolling factors, that is, tectonics, climate, provenance and lake level, among whichtectonics and climate had outstanding effects on the sequence and depression lakeevolution. More over, the author took lake and tectonic evolution into account and builttwo gentle slope sequence patterns and corresponding sequence filling pattern indepression lake basin, which were named expanding-peaking period gentle slopesequence pattern and lake-reconstructing period gentle slope sequence pattern and theircorresponding sequences filling patterns.Secondly, the paper chose the" ratio of sand to strata as the bridge betweendrilling data and seismic data, accomplished integrative mapping of 10 3-D seismic data,which haven't been uniform processed, and mapped six diagrams of ratio of sand tostrata. And also core, logging and other drillings data were applied to map depositionalfacies diagram, and then the author summarized the characteristics of depositional systemsevolution and sands distribution.Thirdly, based on sequence stratigraphic research and depositional system research,the dissertation analysed the time and space distribution rule of lithologic andstratigraphic oil pools in Shinan and adjacent area, and discussed the controlling factorsover oil pools, and then constructed the oil pool forming pattern of lithologic andstratigraphic oil pools in gentle slope, which was outside source rocks. It was indicatedthat the' pattern was characterized by cascade migration pattern. The author furtheranatomised oil pool forming model of key formations.And finally, comprehensively considering the forming conditions of lithologic andstratigraphic traps, play, migration channel, oil pools forming characteristics andexploration prospective, the dissertation discussed the prospective formation and areas.The results were as follows. LST and TST of K-SQ1 ranked the first, TST of J-SQ3ranked the second, J-SQ5 ranked the second and then was J-SQ4. On the plane,Jidong convex nose and Shixi swell were the prospective area for Jurassic sequence andcentral-west Sannan sag was the prospective area for K-SQ1.