The Fluvial-Delta Sedimentary System Analysis Of The Large Scale Nonmarine Depression Basin In Arid Climate

Based on the study of the Quantou No.4 interval of Fuxin uplift zone in south ofSongliao basin, this paper mainly analyzes the sedimentary microfacies and the mainreservoir sand body forms which develops in the low water level and the early stageof the water invading of the large scale nonmarine depression basin under the aridclimate. This paper focuses on four aspects.Firstly, studying in details the texture of the rock, sedimentary structures,sedimentary microfacies, the vertical sedimentary sequence, the thin sections, wellloggings, and other data of 18 drilling cores in Fuxin uplift zone, I conclude that it isprobably to develop meandering river facies in the low water level and shallow waterdelta facies in early stage of the water invading under such arid climate, and thesedimentation is strogly affected by climatic.Secondely, using the indication of the mudstone color in arid climate of the studyarea, the sedimentary facies annalysis and the isopach maps, also combinates withothers data, I conclude that there exist a permanent shallow water lake in Fuyu oilfieldand Xinmin oilfield, and deep-hemideep lake lies in south of the Qijia-GulongSag-Daqing placanticline border area in the stage of Quantou No.4 interval. Thesedimentation in Fuxin uplift zone is supplyed by the southwest Baokang-Tongyuwater family. Only during the later stage of Quantou No.4 interval Songliao big lakebasin came into an embryonic due to the effect of the fast water invasion.Thirdly, the point bar in meandering river, the distributary channel in delta plainand the lower water distributary channel in delta front is the main reservoir sand inmeandering river-the shallow water delata, and the former two is the main reservoir instudy area. The Quantou No.4 interval in Fuxin uplift zone is analyzed in the light ofthe theory of high-frequency sequence stratigraphy, it comprise of 3 fourth-ordersequences. The sand body mainly develops in the early stage of the 4th base levelcycle. The sand body in vertical is rather thick, but the continuity in horizontal is badin Fuxin area, and it is difficult to comparison with other well. The reservoir sandmainly lies in upper of the calcitic cementation which deposits in the upside of thesequence boundary, and it is upward-thinning, the oil saturation distribution alsoupward-worsing. The induced porosity causes by the dissolution is the main form inthis district.At last, I predict that there are two areas worthy of exploration:lies in the districtof Liangjing, Xinli, Mutou oilfield, in north of the Fuyu oilfield and south of theXinmin oilfield, the targets should focus on the point bar in meandering river and thetributary channel in delta plain separately.