Sandstone Sedimentary Facies and Sedimentary Model of Zubair Formation in W Oilfield

The Zubair Formation is a transitional delta sedimentary system, with complex sedimentary microfacies and multiple sets of thin sandstone. The genesis of sand bodies is diverse, with small vertical interlayer spacing and large horizontal thickness variations. It is difficult to predict the distribution of sand bodies between wells. Therefore, it is of great significance to clarify the sedimentary characteristics of the Zubair Formation, determine the sedimentary microfacies, establish sedimentary facies models, and predict the distribution of favorable facies zones for accurate prediction of complex sand reservoirs in the next step. Based on the sedimentary development background of the Zubair Formation's transitional delta, combined with research on rock types, single well facies, logging curve characteristics, and seismic facies analysis, the sedimentary microfacies are identified and the sedimentary evolution laws of sand bodies are revealed. The sedimentary facies model is established. It is pointed out that underwater distributary channels and mouth bars are favorable facies zones, which are most prone to developing high-quality reservoirs. This research provides a geological basis for clarifying the distribution characteristics and genetic mechanisms of sandstone in the Middle East, and provides the study direction for fine seismic inversion of complex sandstone reservoirs in the later stage, and it provides further guidance for the deployment of well locations and the preparation of development plans for reservoirs.