Correlation of Seismic, Well Logging and Pyrolysis Analysis for Evaluating Hydrocarbon Potential – A Case Study of Oil Fields in Muglad Basin, Sudan

Abstract

The Muglad and Melut basins and the Baggara Graben form the oil and gas fields of Sudan and South Sudan. The reservoirs rich in hydrocarbon content are sandstones of the Aptian-Lower Albian Abu Gabra formation deposited during the first rifting phase. Integrated seismic data, well logs and Pyrolysis analysis were carried out to generate correlation models between Azraq, Bamboo and Heglig oil fields in the Muglad rift basin. The study was based on 6 seismic lines, 8 master logs, 4 wireline logs and 303 cutting samples selected from eight wells. The seismic profiles identified the structural effects of normal and reverse faults exist with horst and graben structures formed and give rise to parallel set of faults. The stratigraphic correlation model of well logs has established 12 main units in the Muglad basin, in good agreement with earlier studies. The Rock-Eval pyrolysis results of 303 samples carried out to assess the hydrocarbon content and to evaluate the source rock quality from the Azraq, Bamboo and Heglig wells indicate that the hydrocarbon potentiality of the Abu Gabra formation decreases from the north to south in agreement with the average Total Organic Carbon (TOC) values 2.34, 0.45 and 1.22% respectively. The average values of the Potential Hydrocarbons (S2) also support the TOC results. The correlation model developed from these studies show a general increase of the thickness from the north to south, which emphasizes the fact that the fault system is a result of tectonic rifting of the Muglad basin. The present approach has served as a correlation between the effect of the structural features and the hydrocarbon quality of the Muglad basin.