Research On Sedimentary Facies Of The Second To Fourth Members Of The Qianjiang Formation Of Paleogene In The Zhouhui Area Of ??Qianjiang Depression

In terms of Zhouji-Fanwanhu area of oilfield exploration and development earlier,with the decrease in number and increase of drilling geological reserves,made by the sedimentary facies,reservoir and development achievements are not enough to meet the needs of the present stage of rolling development,so it is necessary to return to tap the old potential of Zhou Ji-FanWanHu area.In this paper,the high resolution sequence stratigraphy theory,make full use of the theory of sedimentology,geochemistry,logging geology and seismic sedimentology,through in-depth analysis of the Jianghan Basin in Qianjiang sag of Paleogene zhoufan area basic geology data of Qianjiang two-four group latent period,combined with previous research results,comprehensive core data,measurement logging data,seismic data and test data,the sedimentary characteristics of the study area were studied.Through the analysis of the data of formation thickness,rock characteristics,sandstone maturity and sand ratio,and combining with previous research results,it is clear that the source direction of Qianjiang formation in the study area is mainly from the northwest of the study area.According to the theory of high resolution sequence stratigraphy,combined with core,survey logging and internal research report,the submersible two segment high resolution sequence stratigraphic division scheme of submersible four segments,that is,3 long-term cycles,11 mid-term cycles and 56 short-term cycles.On this basis,through the observation of 13 core wells in the study area,combined with the regional geological background,drilling data,well logging and seismic facies analysis,it is believed that the deltaic lake depositional system is mainly developed in the two-four segment of the study area,and further identifies the delta front subfacies,the anterior delta subfacies and the shallow lake subfacies(light and semi saline water).5 subfacies,and lake,shallow lake subfacies(Saline Lake),half deep lake and deep lake subfacies(Saline Lake),and 14 sedimentary microfacies such as underwater distributary channel,estuarine dam,far sand dam,front mat sand,beach bar,etc.,and describe each sedimentary microfacies in detail.At the same time,the sedimentary facies is compared in the sequence stratigraphic framework with the short term base level cycle as the contrast unit,and the sedimentary microfacies extension range is determined through the stratigraphic thickness,sand ratio and the sandstone thickness contour map,and the sedimentary microfacies map is plotted.Finally,on the basis of the sedimentary facies division of the key wells,the relative map of the well deposition and the sedimentary facies,and combining with the characteristics of tectonic evolution,the deposition of the two-four segment of the Paleogene Qianjiang formation in the Zhou-return area is derived from the deposition of the deltaic front delta shallow lake(light and salt water lake)-the shallow lake(Saline Lake)-the semi deep lake deep lake(Saline Lake).PatternBased on the above research,combined with previous research results and exploration and development status,analysis and research show that the microfaces sandbody of the underwater distributary channel has the best reservoir performance,followed by the estuary dam and the distal bar micro faces sand body,and the beach bar microfaces sand body has the worst reservoir performance.