The Zarga and Ghazal formations constitute important reservoirs across the Muglad Basin, Sudan. Nevertheless, the sedimentology and diagenesis of these reservoir intervals have hitherto received insignificant research attention. Detailed understanding of sedimentary facies and diagenesis could enhance geological and geophysical data for better exploration and production and minimize risks. In this study, subsurface reservoir cores representing the Zarga formation (1114.70–1118.50 m and 1118.50–1125.30 m), and the Ghazal formation (91,403.30–1406.83 m) were subjected to sedimentological (lithofacies and grain size), petrographic/mineralogic (thin section, XRD, SEM), and petrophysical (porosity and permeability) analyses to describe their reservoir quality, provenance, and depositional environments. Eight (8) different lithofacies, texturally characterized as moderately to well-sorted, and medium to coarse-grained, sub-feldspathic to feldspathic arenite were distinguished in the cored intervals. Mono-crystalline quartz (19.3–26.2%) predominated over polycrystalline quartz (2.6–13.8%), feldspar (6.6–10.3%), and mica (1.4–7.6%) being the most prominent constituent of the reservoir rocks. Provenance plot indicated the sediments were from a transitional continental provenance setting. The overall vertical sequence, composition, and internal sedimentary structures of the lithofacies suggest a fluvial-to-deltaic depositional environment for the Ghazal formation, while the Zarga formation indicated a dominant deltaic setting. Kaolinite occurs mainly as authigenic mineral, while carbonates quantitatively fluctuate with an insignificant amount of quartz overgrowths in most of the analyzed cores. Integration of XRD, SEM, and thin section analysis highlights that kaolinite, chlorite, illite, and smectite are present as authigenic minerals. Pore-destroying diagenetic processes (e.g. precipitation, cementation, and compaction etc.) generally prevailed over pore-enhancing processes (e.g. dissolution). Point-counted datasets indicate a better reservoir quality for the Ghazal formation (ɸ = 27.7% to 30.7%; K = 9.65 mD to 1196.71 mD) than the Zarga formation (17.9% to 24.5%; K = 1051.09 mD to 1090.45 mD).
Floodplains of Sokoto Basin with covering about 280,000 hectares of land was assessed for its shallow groundwater potentials. Data on pumping test of tube wells, logs and drilled tube wells were utilized for this study. Storativity was determined from known lithology of tube wells. Results of this study gives the ranges and averages of Hydraulic parameters for the shallow alluvial aquifers of hydraulic conductivity, transmissivity, specific capacity and storativity to be 6. -5 -6×10 -3 and 5×10 -4 respectively, While the Yields range of 0.3-7 l/s was obtained with 90% of tube wells evaluated having yields of 2.2 l/s and above. Lithologic Aquiferous units vary from medium sands, sands, coarse sands to gravel with thickness range of between 0.3 to 15 m. Computed hydraulic conductivity indicates the aquifer materials to be gravels and alluvial sands of high permeability. Specific capacity values indicated the wells to be of high productivity when compared with standard values, Transmissivity average revealed the area to be of high groundwater transmission potentials. Overall assessment of the yields of tube wells studied indicated that 90% of the wells have yields that are above the minimum required for irrigation; the low average drawdown of 0.41 m recorded is an indication that the aquifers have high efficiency and high performance as regards storage and transmission of water. Recharge of the alluvial aquifers is mainly through surface river flow and precipitation, climate change have recently threaten the recharge potential s owing to the drying up of some of these streams and rivers at the peak of dry season as well reduction in rainfall. Statistical analysis has shown a good linear relationship between Specific capacity with yield, Transmissivity and hydraulic conductivity while Transmissivity is linearly related with yield and Conductivity. Generally the study revealed that the Sokoto basin Fadama land to be of high groundwater potentials, with storage coefficient values of confined and high yielding aquifers with capabilities of sustaining withdrawals for long period without recharge from external sources. Standard procedures are highly recommended to reduce or avoid the case of drilling abortive or low yielding wells.
A geophysical survey employing Schlumberger electrode configuration using vertical electrical sounding (VES) method was carried out around Chibok area within the Basement Complex of north-eastern Nigeria using an ABEM SAS 300C Terrameter with a view to exploring groundwater within the study area. The overburden in the area ranges from about 15m to 58.5m thick. This overburden, based on geoelectrical interpretations, consists essentially of top soil, decomposed crystalline rock, highly weathered crystalline rock, weathered or fractured crystalline rock and weathered to fresh crystalline rock. The study suggest that the vicinities of all the VESs are best suited for the siting of boreholes apart from VES 1 and 5 due to the presence of fresh crystalline rock at shallow depth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.