| Oil and gas is very rich in Shinan area in the central of Junggar basin. And it is very important in academic and practical study for stratigraphic traps exploration in this area and even the whole central of Junggar basin, through researching the characteristics of sequence, deposition and stratigraphic traps forming in this area.This dissertation adopted the reserch path of point (cores,wells)-line(profiles)-surface(attributes, sedimentary facies)-tract(temporal evolution and spacial distribution)-line(filling patterns)-point(range of intrest, traps) and chose J1s-K1q1 formation in Shinan area, central Junggar basin as research object and conducted sequence stratigraphic research, depositional system evolution characteristics and lithologic and stratigraphic prospective areas.The paper used squence stratigraphy theory to build the 4th sequence stratigraphic framework and built three types of squence filling patterns of gentle slope in depression basin, i.e. expanding-peaking period gentle slope sequence filling pattern, tectonic dormant period gentle slope sequence filling pattern and lake-reconstructing period gentle slope sequence pattern. These patterns were controled by tectonics, sediment supply and climate, among which tectonics and climate determined eustacy and the eustacy determined the variation of accommodation and A/S determined the archtecture of sequence. Dissertation also summarized the corresponding three types of depositional filling patterns, which named expanding-peaking period gentle slope depositional filling pattern, tectonic dormant period gentle slope depositional filling pattern and lake-reconstructin period gentle slope depositional pattern.The expanding-peaking period gentle slope filling pattern was corresponding to J1SQ3 cycle sequence. During lowstand system tract depositing, the topography was gentle, the braided delta front devoloped, the sand body was multi-statum superimposed. During transgressive system tract depositing, water rised rapidly, the retograding delta and beach bar devoloped which the sand body was stacked isolatedly. Lithologic traps were easy to develop for good adjoining rock, but the physical property of reservoir was poor. Tectonic dormant period gentle slope filling pattern was corresponding to J2SQ2 residual cycle sequence which develop two period of transgressive deposition. Early stage, the lake level was shallower, the resoucees were unequilibrated and delta plain developed in research area. Late period, resouce were increasing and multi-resouce delta front developed which was the favorable litho-stratigraphic area. Lake-reconstructin period gentle slope depositional pattern was corresponding to K1SQ1 uplift hemicycle sequence. Duing landstand system tract depositing, braided delta front devoloped in valleys and sags where the sand bodies were stacked successively and it was probable to develop lithologic traps in delta plain and to develop stratigraphic traps in strata fringe. During transgressive system tract depositing, lake level was rising when lacustrine and retrogradational delta sediments devoloped. Meanwhile the pre-delta slump fans took shape because of abrupt events which the oil field of Shina 31 is just belong to this type sand body.In the cause of litho-stratigraphic trap recognizing, dissertation summarized the industrializational flow chart of litho-stratigraphic trap recognition and evaluation, i.e. based on sequence stratigraphy and reservoir research, the seismic anomalous bodies were recognized on the basis of the seismic data and drill/well-logging data. And taking filling patterns as instruction, many geophisical methods were used to set up litho-stratigraphic traps development patterns. In the end, the writer comprehensively evaluated the found traps on sand body superimposition and reservoir-cap rock assemblage, top stucture isogram of traps, play analysis, venture analysis and so on.
|
PDF Full Text Request