Tectonic Evolution Analysis And Distribution Of Sedimentary Facies In Rawat Basin,Sudan

The Rawat Basin in Sudan is a fault basin formed during the Mesozoic Cenozoic in the Central African shear stress extension zone,which is divided into five sub basins.Numerous oil bearing depressions have been discovered in the Melut Basin of the same type in the adjacent area,so the basin also has great exploration potential.Due to the current exploration stage of the Rawat Basin,there is a lack of clear understanding of the basin’s structural evolution,sequence stratigraphy,and sedimentary facies distribution in the early stage.There are many failed wells,and only oil and gas discoveries have been found in the eastern gentle slope area of the central sub basin.Therefore,it is necessary to conduct research on the structural evolution,sequence stratigraphy,and sedimentary facies distribution patterns to further determine favorable areas and guide the next drilling deployment.Therefore,this study has pioneering and guiding significance for the exploration and development of the region.Firstly,based on the results of structural interpretation,combined with structural feature analysis,the study explored the tectonic evolution process of the basin using the twodimensional equilibrium profile method and three-dimensional structural modeling method;Then,using drilling and seismic data for sequence identification and division,the entire basin stratigraphic framework was established;Subsequently,combined with core data,logging data,seismic reflection characteristics,and waveform seismic attributes,a study was conducted on the distribution patterns of sedimentary facies in the main target layers throughout the basin.Finally,a sedimentary model was established for the region,and favorable sedimentary zones were determined,laying the foundation for later reservoir prediction and reservoir formation research.The main findings of the study are as follows: the basin developed three tectonic cycles,with the Galhak Formation of the Upper Cretaceous to the Yabus Formation of the Eocene being the first stage of rifting,the Adar Formation of the Oligocene being the second stage of rifting,and the Jimidi Formation of the Neogene to the Agor Formation of the Quaternary being the third stage of overall depression.Five sets of sequence stratigraphy(SQ1-SQ5)are mainly developed in the basin,of which Galhak and Melut layers corresponding to SQ1 and SQ2 are the main target layers,and sedimentary facies mainly include delta,alluvial fan,fan delta and shallow lake facies.The west sub basin of Rawat basin is mainly of alluvial fan facies,the central sub basin,the north sub basin,the east sub basin and the southeast sub basin are mainly of delta facies in gentle slope area,and the steep slope area is mainly of fan delta facies.The delta front subfacies and fan delta facies are favorable sedimentary facies in this area.Due to the fact that the main target layers of the Rawat Basin are the Galhak and Melut layers,these sedimentary facies study mainly focuses on the Galhak and Melut layers,and does not specifically involve the Yabus and above layers.Therefore,the sedimentary facies types and distribution characteristics need to be further studied and implemented by other scholars in the later stage.