Predicting porosity distribution using sequential Gaussian simulation: A case study of the Galhak Formation in the Rawat Central Field, Sudan
Awad M.Z. Quer H.B.H. Hassan A.H.O. Abdullatif O.
January 2026Elsevier Ltd
Journal of African Earth Sciences
2026#234
Accurate inter-well porosity prediction is critical for quantifying uncertainty in unsampled locations, particularly in structurally complex reservoirs with limited well data. This study presents a geostatistical porosity modeling framework based on Sequential Gaussian Simulation (SGS), tailored to the structural and depositional complexities of the Galhak Formation in the Rawat Central Field. Stationarity was assessed through statistical and analytical methods, followed by systematic optimization of variogram parameters, including azimuth, dip, angular tolerance, and bandwidth to characterize spatial correlation in the fluvial–deltaic depositional environment and structural dip of the area. Variogram analysis revealed quasi-isotropic horizontal correlation with an effective range of approximately 600 m, significant vertical anisotropy (100:1) with a 6-m vertical correlation, and periodic hole effects reflecting parasequence-scale depositional cyclicity. These fitted variogram models were validated against interpreted facies distribution and parasequence stacking patterns, and then used as inputs for SGS, which generated five stochastic realizations. The realizations yielded a mean porosity of 14.2 % ± 3.8 % across the field, with high-confidence zones (>18 % porosity) centered in the central–eastern region and low uncertainty (variance <1.0) covering 60 % of the study area. Model validation showed a root mean square error of 2.8 % and a correlation coefficient of 0.89, confirming the approachs effectiveness for capturing spatial heterogeneity and quantifying uncertainty. This framework underscores the significance of detailed variogram calibration and integration of geological controls for producing replicable porosity predictions in data-limited, structurally complex reservoirs, offering a transferable methodology for similar fluvial–deltaic systems.
Fluvial–deltaic environment , Galhak formation , Porosity prediction , Sequential Gaussian simulation , Uncertainty quantification , Variogram analysis
Text of the article Перейти на текст статьи
University of Khartoum, Faculty of Science, Department of Geology, Sudan
School of Geophysics and Geomatics, China University of Geosciences, Wuhan, 430074, China
Nazarbayev University, School of Mining and Geosciences, Kazakhstan
Special Environmental Projects Company, Al Khobar, Saudi Arabia
University of Khartoum
School of Geophysics and Geomatics
Nazarbayev University
Special Environmental Projects Company
10 лет помогаем публиковать статьи Международный издатель
Книга Публикация научной статьи Волощук 2026 Book Publication of a scientific article 2026