Restoration Of The Faulted Period Basin In The Sujiatun Subsubsag Of Lishu Rift

Sujiatun subsubsag is located in the northwest of Lishu fault depression, the multi-stage tectonic movements of Sujiatun subsubsag, it formed the complex fault system and a variety of different oil-bearing structural styles. However, so far at different stages of Sujiatun subsag in the faulted period the original appearance for the lack of a detailed analysis with the deposition. Therefore, at present, it will has a reality significance for petroleum exploration in the Sujiatun subsag to research holistically and systematically of original appearance basin in the faulted period.Taking the theories of structural geology, basin analysis, petroleum geology, sedimentology and as guidance, with the3d seismic data in the study area, while taking advantage of well drilling, seismic and other aspects of data and information, the paper tells how tectonic geomorphology controlled development and distribution of deposition system during the fault time and then restoration of the faulted period basin in the Sujiatun subsag. The results show.By analyzing structural fault evolution, three stages of tectonic evolution including Initial rift in Huoshiling stage, quick stretch in Shahezi and Yingcheng stage and rift atrophy in Denglouku and early Quantou stage are divided. In Huoshiling stage, in the environment of crust uprising and tension, and right lateral strike-slip, Sujiatun fault and the contacting zone both are not developed, Pijia fault and adjacent area began stretch, the rudiment of Sujiatun subsag formed. In Shahezi-Yingcheng stage, all regions were exacerbated extensional movement and subside, gradually increasing scale of Sujiatun subsag, with the deposit and overlap in Shahezi strata and yingcheng strata, in last of Yingcheng stage, due to the impact of area extruding stress, the subsag reversed, that strata in the west are thicker than those in the east, in the west and transgression in the east in tectonic style. In Denglouku-early Quantou stage, in the right-lateral strike-slip environment, with the increase in strike slip motion, began to rapid subsidence, compared to the Yingcheng strata of fault significantly weakened, the fault almost stopped in the early Quantou stage.Sujiatun subsag can be divided into7kinds of core microfacies types. Fan delta, braid delta, nearshore subaqueous fans and lacustrine facies are found according to a variety of sedimentary marks. In Huoshiling stage, the shallow lake and the fan delta around the lake were developed, away from the edge of the lake district sag alluvial fan and alluvial plains, lake limited distribution and mostly shallow lakes. In early Shahezi stage, the depositions were limited distribution and most areas cessation of deposition. In middle Shahezi stage, from the northeast-southwest braid river delta plain subfacies, braided river delta front subfacies, shallow lake, semi-deep lake facies. In late Shahezi stage, near Sangshutai fault the nearshore subaqueous fans were developed.In early Yingcheng stage, the shallow lake-semi-deep lake facies of large area development, from the northwest-southeast braided river delta plain subfacies, braided river delta front subfacies, shallow lake facies and semi-deep lake facies. In middle-late Yingcheng stage, deposition pattern of inheritance of the early deposition. In Denglouku-early Quantou stage, the lake facies as the center, braided river, braided delta facies surrounding.