Application of full-azimuth prestack gathers in the prediction of fractured-vuggy reservoirs of granite bedrock buried hills: A case study of Baobab buried hill in Bongor Basin, Chad

There are some problems in the prediction of fractured-vuggy reservoirs of granite bedrock buried hills, such as low imaging precision, strong multi-solutions and low resolution of fracture prediction results, and weak seismic response of caves, thus restricting the exploration efficiency of internal oil and gas reservoirs. Taking Baobab buried hill in Bongor Basin, Chad as an example and based on the depth migration processing method of full-azimuth local angle domain, angle domain decomposition and imaging was applied to obtain the true angle domain information of the formation, and the full-azimuth common reflection angle gathers and full-azimuth common dip angle gathers were extracted to improve the imaging precision of buried hills and the prediction accuracy of fractures and caves. Guided by the geological development mode of fractured-vuggy reservoirs of the buried hills, the fracture development intensity of Baobab buried hill was predicted using full-azimuth common reflection angle gathers, thus effectively improving the fracture prediction precision and reducing the multi-solutions for fracture prediction. Scattering imaging processing of full-azimuth common dip angle gathers can strengthen the geometrical characteristics beyond seismic resolution, highlight the discontinuity of small-scale geological bodies, and clearly identify karst caves on the seismic sections. The research method has achieved a good prediction result in Baobab buried hill and has certain application prospect and promotion significance in the fractured-vuggy reservoirs of granite bedrock buried hills. © 2022 Science Press. All rights reserved.