Lithology correlation and Petrophysics Evaluation in Ghazal Formation Hilba East Oil Field-Muglad Basin, Sudan

Abstract

Petrophysical evaluation study had been done of the Ghazal formation-Muglad basin, Hilba East oil field. That located in the northern corner of Block-4, Hilba wells cluster lie about 16 Km NW of Neem field. Well log data from four wells had been used for lithological interpretation and fluids assessment. Previous studies have shown that the area is faulted many times the reason which makes different values of depth to mark the top of Ghazal formation along the four wells that have been drilled in the area. In the current study Ghazal formation had been evaluated manually and compared with interpretation for all logs have been done to confirm the software results and identify the type of lithology, the quality of reservoir, estimate the Porosity ,Volume of shale, water saturation and discover a new productive zone as well as their continuity. Interactive Petrophysics version 3.5 software had been used in this study and results to the evaluation of three petrophysical parameters range as follow: the effective porosity (16% - 19%), average volume of shale (22% – 35%) and Average of water saturation (71%-83%). The main important problem in this research was the low resistivity that created many difficulties in interpretation process, the solution of this problem using Thomas-Stieber volumetric method crossplots approach defined a relationship based on gamma ray log to total porosity facilitates identification of thin-bed sand/shale. The result obtained reveal that average volume of shale is increasing in the center of study area, toward (H E-3) due to inverse relation of clay volume with porosity therefore the porosity increasing away from the center where the high hydrocarbon potentiality (Hilba East-1), While the water saturation decreased away from the center (Hilba East-3) due to increasing of hydrocarbon saturation. The gas ratio analysis data (Gas chromatography) had been computed manually to estimate the type and quality of petroleum in reservoir of Ghazal Formation.