This study compares reverse circulation (RC) and diamond core (CD) drilling for exploring phosphate nodules in Nigeria’s Sokoto Basin. A programme of 15 RC wells (1000 m) and 2 CD wells (151 m) assessed performance metrics. RC drilling was significantly faster, progressing three times quicker than CD, and successfully identified phosphate layers 93% of the time. However, its bulk samples caused nodule breakage, reducing grade accuracy. Conversely, CD provided intact cores for precise stratigraphy with 78% recovery but was slower and 40% more expensive. Mineralisation was found primarily in the Dange formation’s gypsiferous shales, with optimal depths varying regionally from under 15 to over 100 metres. The analysis concludes RC is best for rapid lateral resource scoping, while CD is essential for detailed vertical delineation. A cost-time trade-off exists, favouring a hybrid strategy: initial RC mapping followed by targeted CD for reserve classification. The findings offer an optimisation framework for sedimentary phosphate exploration, though future work should integrate advanced coring and 3D modelling to better account for the basin’s geological trends.
Awalla, C.O., Ezeh, C.C. and Nwabufo-Ene, K.E. (2002) Review of Sokoto Phosphate Deposit Sokoto, Nigeria. Global Journal of Pure and Applied Sciences , 8, 89-93. https://doi.org/10.4314/gjpas.v8i1.16336
Mustapha, S.O., Olatunji, A.S., Ajayi, F.F. and Isibor, R.A. (2022) Mineralogy and Geochemistry of Some Phosphate Deposits for Possible Rare Earth Elements Mineralization Potentials within Sokoto Basin, Northwestern Nigeria. Indian Journal of Science and Technology , 15, 2570-2578. https://doi.org/10.17485/ijst/v15i46.1603
Okosun, E.A. and Alkali, Y.B. (2013) The Geochemistry, Origin and Reserve Evaluation of Sokoto Phosphate Deposit, North Western, Nigeria. Earth Science Research , 2, 111-121. https://doi.org/10.5539/esr.v2n2p111
Obaje, N.G., Faruq, U.Z., Bomai, A., Dabai Moses, S., Ali, M., Adamu, S., et al . (2020) A Short Note on the Petroleum Potential of the Sokoto Basin in North-Western Nigeria. Petroleum Science and Engineering , 4, 34-38. https://doi.org/10.11648/j.pse.20200401.14
Obaje, S.O., Ojutalayo, A., Ogedengbe, O. and Okosun, E.A. (2014) Nigeria’s Phosphate and Uranium Mineral Occurrences: Implication for Mineral Investment. Journal of Environmental & Earth Sciences , 4, 83-89.
Onuigbo, E.N., Okoro, A.U. and Nwokeabia, C.N. (2017) Clay Minerals as Indicator of Phosphatogenesis: A Case Study of Sokoto Basin, Northwestern Nigeria. Journal of Natural Sciences Research , 7, 21-27.
Amer, M.Y., Salem, S.K., Farahat, M.S. and Salem, A.M. (2025) Reducing Drilling Cost of Geothermal Wells by Optimizing Drilling Operations: Cost Effective Study. Unconventional Resources , 7, Article ID: 100196. https://doi.org/10.1016/j.uncres.2025.100196
Babayeju, O.A., Jambol, D.D. and Esiri, A.E. (2025) Reducing Drilling Risks through Enhanced Reservoir Characterization for Safer Oil and Gas Operations. GSC Advanced Research and Reviews , 19, 86-101. https://doi.org/10.30574/gscarr.2024.19.3.0205
Ganat, T.A.O. (2020) Understanding Exploration, Appraisal and Production Stages. In: Al-Arbi Omar Ganat, T., Ed., Technical Guidance for Petroleum Exploration and Production Plans , Springer International Publishing, 21-28. https://doi.org/10.1007/978-3-030-45250-6_3
Iwe, K.A., Isong, D.E., Daramola, G.O. and Agho, M.O. (2021) Sustainable Pore Pressure Prediction and Its Impact on Geo-Mechanical Modelling for Enhanced Drilling Operations. World Journal of Advanced Research and Reviews , 12, 540-557. https://doi.org/10.30574/wjarr.2021.12.1.0536
Kaiser, M.J. (2021) A Review of Exploration, Development, and Production Cost Offshore Newfoundland. Natural Resources Research , 30, 1253-1290. https://doi.org/10.1007/s11053-020-09784-3
Bruno, P.P.G. (2023) Seismic Exploration Methods for Structural Studies and for Active Fault Characterization: A Review. Applied Sciences , 13, Article No. 9473. https://doi.org/10.3390/app13169473
Groves, D.I., Santosh, M. and Zhang, L. (2020) A Scale-Integrated Exploration Model for Orogenic Gold Deposits Based on a Mineral System Approach. Geoscience Frontiers , 11, 719-738. https://doi.org/10.1016/j.gsf.2019.12.007
Hill, E.J., Fabris, A., Uvarova, Y. and Tiddy, C. (2021) Improving Geological Logging of Drill Holes Using Geochemical Data and Data Analytics for Mineral Exploration in the Gawler Ranges, South Australia. Australian Journal of Earth Sciences , 70, 1067-1093. https://doi.org/10.1080/08120099.2021.1971763
Liu, L., Li, T. and Ma, C. (2024) Research on 3D Geological Modeling Method Based on Deep Neural Networks for Drilling Data. Applied Sciences , 14, Article No. 423. https://doi.org/10.3390/app14010423
Tshanga M, M., Ncube, L. and van Niekerk, E. (2024) Remote Sensing Insights into Subsurface-Surface Relationships: Land Cover Analysis and Copper Deposits Exploration. Earth Science Informatics , 17, 3979-4000. https://doi.org/10.1007/s12145-024-01423-2
Zhao, J., He, L., Gong, J., He, Z., Feng, Z., Pang, J., et al . (2025) Predicting Manganese Mineralization Using Multi-Source Remote Sensing and Machine Learning: A Case Study from the Malkansu Manganese Belt, Western Kunlun. Minerals , 15, Article No. 113. https://doi.org/10.3390/min15020113
Zhao, T., Wang, S., Ouyang, C., Chen, M., Liu, C., Zhang, J., et al . (2024) Artificial Intelligence for Geoscience: Progress, Challenges, and Perspectives. The Innovation , 5, Article ID: 100691. https://doi.org/10.1016/j.xinn.2024.100691
Sarath, H. and Manuel, J.R. (2010) Techniques Used and Problems Encountered in Normal and Reverse Circulation Drilling at the Mt Roseby Project, Cloncurry, Northwest Queensland. XXV International Mineral Processing Congress ( IMPC ) 2010, Brisbane, 6-10 September 2010.
Li, L., Ru, D., Li, K. and Yishan, W. (2006) Research and Application of Reverse Circulation Drilling Technology. International Oil & Gas Conference and Exhibition in China , Beijing, December 2006, SPE-104412-MS. https://doi.org/10.2118/104412-ms
Orpen, J. and Orpen, D. (2020) Error-Proofing Diamond Drilling and Drill Core Measurements. SEG Discovery , 123, 23-34. https://doi.org/10.5382/geo-and-mining-09
Aghlan, M.H., Asghari, O. and Emery, X. (2025) Optimizing Infill Drill Hole Decisions While Capturing the Spatial Continuity of Geochemical and Geometallurgical Properties: Application to Gol Gohar Iron Ore Mine, Iran. Minerals , 15, Article No. 478. https://doi.org/10.3390/min15050478
Nicholls, L.V. (2025) Multi-Scale Geometallurgical Characterisation of Legacy Tail-ings for Sustainable Critical Metal Valorisation: A Case Study Exploring the Secondary Prospectivity of Cobalt. PhD Thesis, University of Queensland, 576 p.
Kalpande, V. and Wahhab, A. (2019) Data Mining Analytics of Exploration Drilling Well Cost for Petroleum Economics in Western Offshore India. Petro Tech Conference 2019, New Delhi, 10-12 February 2019, 2233.
Riazi, K., Azhari, H., Charette, J.H., Underwood, F.E., King, J.A., Afshar, E.E., et al . (2022) The Prevalence and Incidence of NAFLD Worldwide: A Systematic Review and Meta-Analysis. The Lancet Gastroenterology & Hepatology , 7, 851-861. https://doi.org/10.1016/s2468-1253(22)00165-0
Rock, O.M., Omonona, V.O. and Abraham, E.M. (2017) Exploring and Reserve Estimation for Industrial Mineral Potential in Parts of Calabar Area (Ewen/Iwuru/Agbangana Axis) Southern Nigeria. Journal of Geology & Geophysics , 6, Article ID: 1000317.
Sterk, R. and Franey, D. (2017) RC Drilling and Sampling: Optimising the Quantity-Quality Balance. Book / Conference Proceedings for the Drilling for Geology Conferen ce , Brisbane, May 2017, 17 p.
Allaire, A., Dorval, A., Beaulieu, C., Girard, M., Paquette, M.-H., Millet, E., Farhangi, S. and Khoury, T. (2024) Pre-Feasibility Study for the Kamistiatusset (Kami) Iron Ore Property Newfoundland and Labrador, Canada. NI 43-101 Technical Report, BBA Document No.: 3813101-000000-40-ERA-0001-R00.
Ghaffari, H., Huang, J.J., Li, J.J. and O’brien, M.F. (2024) Oxide Tailings Project Prefeasibility Study for the Avino Property, Durango, Mexico, NI 43-101 Technical Report. Tetra Tech Canada Inc.
Hatton, M., Lewis, M., Jones, L., Howery, J., Franceschini, M., McIntyre, A. and Kalenchuk, K. (2022) Technical Report on the Feasibility Study for the McIlvenna Bay Project, Saskatchewan Canada. Foran Mining Corporation, NI 43-101, Project Number: 169521520.
Oghenebrume, U.L. and Abiodun, O.A. (2025) Optimization of Drilling Bit Performance: A Cost-per-Foot and Breakeven Analysis of Well-A and Well-B at Pan Ocean Oil Corporation Nigeria. British Journal of Multidisciplinary and Advanced Studies , 6, 9-26. https://doi.org/10.37745/bjmas.2022.04912
Wang, X., Dong, J., Liu, J. and Lyu, J. (2021) Brief Analysis of Cost per Meter Management in Drilling and Well Completion Operations in Bohai Oilfield. Academic Journal of Business & Management , 3, 59-63.
Hapugoda, S. and Manuel, J. (2010) Techniques Used and Problems Encountered in Normal and Reverse Circulation Drilling at the Mt Roseby Project, Cloncurry, Northwest Queensland. XXV International Mineral Processing Congress ( IMPC ) 2010 Proceedings , Brisbane, 6-10 September 2010.
Stanić, T. (2023) Assessing the Feasibility and Effectiveness of Reverse Circulation in Drilling Operation. Unpublished Master’s Thesis, Montan Universitat Leoben, 136. https://pure.unileoben.ac.at/ws/portalfiles/portal/24898652/AC17033493.pdf
Engström, K. (2017) A Comprehensive Literature Review Reflecting Fifteen Years of Debate Regarding the Representativity of Reverse Circulation vs Blast Hole Drill Sampling. TOS Forum , 2013, 36-46. https://doi.org/10.1255/tosf.99
Annels, A.E. and Dominy, S.C. (2003) Core Recovery and Quality: Important Factors in Mineral Resource Estimation. Applied Earth Science , 112, 305-312. https://doi.org/10.1179/037174503225011306
Szilas, C. (2022) The Tanzanian Minjingu Phosphate Rock—Possibilities and Limitations for Direct Application. Unpublished PhD Thesis, Royal Veterinary and Agri-cultural University, 178. https://www.gpsagro.dk/thesis.pdf
Qin, X.Q. (2025) Geochemistry of Trace Metals Associated with Fe-Mn Nodules (FMNs) of Red Soil Profiles in China. Unpublished PhD Thesis, Université Paris Cité, NNT: 2024UNIP7087. https://theses.hal.science/tel-04989843v1/file/va_Qin_Xiaoquan.pdf
Raabe, D., Sun, B., Da Silva, A.K., Gault, B., Yen, H., Sedighiani, K., et al . (2020) Current Challenges and Opportunities in Microstructure-Related Properties of Advanced High-Strength Steels. Metallurgical and Materials Transactions A , 51, 5517-5586. https://doi.org/10.1007/s11661-020-05947-2
Amon, D.J., Gollner, S., Morato, T., Smith, C.R., Chen, C., Christiansen, S., et al . (2022) Assessment of Scientific Gaps Related to the Effective Environmental Management of Deep-Seabed Mining. Marine Policy , 138, 105006. https://doi.org/10.1016/j.marpol.2022.105006
Dominy, S.C. and Glass, H.J. (2025) Geometallurgical Sampling and Testwork for Gold Mineralisation: General Considerations and a Case Study. Minerals , 15, Article No. 370. https://doi.org/10.3390/min15040370
Sketchley, D.A. (1998) Gold Deposits: Establishing Sampling Protocols and Monitoring Quality Control. Exploration and Mining Geology , 7, 129-138.
Heddoun, O., Ait Lemkademe, A. and Benzaazoua, M. (2025) Comprehensive Hydrogeological Analysis of the Beni Amir Deposit in the Oulad Abdoun Phosphate Basin, Morocco. Mine Water and the Environment , 44, 482-501. https://doi.org/10.1007/s10230-025-01034-3
Dehkordi, M.M., Nodeh, Z.P., Dehkordi, K.S., salmanvandi, H., Khorjestan, R.R. and Ghaffarzadeh, M. (2024) Soil, Air, and Water Pollution from Mining and Industrial Activities: Sources of Pollution, Environmental Impacts, and Prevention and Control Methods. Results in Engineering , 23, Article ID: 102729. https://doi.org/10.1016/j.rineng.2024.102729
Adelana, S.M.A., Olasehinde, P.I. and Vrbka, P. (2006) A Quantitative Estimation of Groundwater Recharge in Part of the Sokoto Basin, Nigeria. Journal of Environmental Hydrology , 14, 1-14.
Obaje, N.G., Aduku, M. and Yusuf, I. (2013) The Sokoto Basin of Northwestern Nigeria: A Preliminary Assessment of the Hydrocarbon Prospectivity. Petroleum Technology Development Journal , 3, 71-86.
Ezeh, O.C., Egwuonwu, G.N., Amadansun, C.V.O. and Umego, M.N. (2021) Source Parameter Imaging of Aeromagnetic Map of Sokoto Basin, Northwestern Nigeria. International Journal of Mechanical and Civil Engineering , 4, 1-11.
Abubakar, A., Likkason, O.K., Abdulganiyu, Y., Tsafe, H.U., Mahmood, U., Balarabe, B., et al . (2024) Investigation into a Deep-Rooted Crustal Framework Deduced from Potential Field Data in Cretaceous and Tertiary Strata, Sokoto Basin NW, Nigeria. Science World Journal , 18, 526-540. https://doi.org/10.4314/swj.v18i4.2
Wali, S.U., Gada, M.A., Dankani, I.M. and Hamisu, I. (2022) Relating Groundwater to Geology in Sokoto Basin, North-Western Nigeria Using Multivariate and Regression Analysis: Implications for Groundwater Availability. International Journal of Hydrology , 6, 57-65. https://doi.org/10.15406/ijh.2022.06.00302
Bonde, D.S., Udensi, E.E. and Rai, J.K. (2014) Spectral Depth Analysis of Sokoto Basin. IOSR Journal of Applied Physics , 6, 15-21. https://doi.org/10.9790/4861-06111521
Christopher, O.A., Alaga, T.A. and Ogbole, O.J. (2016) Geological Site Suitability in Sokoto State, Northwestern Nigeria, for Phosphates Prospecting. Greener Journal of Geology and Earth Sciences , 4, 40-50. https://doi.org/10.15580/gjges.2016.2.062716108
Obaje, N.G., Faruq, U.Z., Bomai, A., Moses, S.D., Ali, M.S., Adamu, S., et al . (2020) Advances on the Geology and Evaluation of Potential Petroleum Systems of the Sokoto Basin in NW Nigeria. African Journal of Engineering and Environment Research , 1, 78-92.
Ogbesejana, A.B., Radda, F.D., Gobirawa, N.S., Muazu, L.A., Okunola, O.J. and Bello O.M. (2024) Elemental Geochemistry of the Late Paleocene Shales from Dange and Gamba Formations, Sokoto Basin, Northwest Nigeria. Nigerian Research Journal of Chemical Sciences , 12, 23-50. http://www.unn.edu.ng/nigerian-research-journal-of-chemical-sciences
Ozumba, B.M. (2018) Potential Reservoir Rock Characteristics of the Sokoto Sector of the Iullemmeden Basin: Geological Similarities with the Niger Delta Petroleum Province and Prospects for Hydrocarbon Discovery. Archives of Petroleum & Environmental Biotechnology , 2018, 1-15.
Magawata, U.Z., Olasunkanmi, N.K., Egbeyale, G.B. and Saleh, A. (2025) Structure and Mineralization Potential of the Southwestern Part of Sokoto Basin in Nigeria. Frontiers in Earth Science , 13, Article ID: 1500162. https://doi.org/10.3389/feart.2025.1500162
Aisabokhae, J.E. (2021) Geophysical Mapping and Mineralisation Characterisation of the Mesothermal Auriferous Basement Complex in Southern Kebbi, NW Nigeria. NRIAG Journal of Astronomy and Geophysics , 10, 443-465. https://doi.org/10.1080/20909977.2021.2005333
Brookfield, M.E., Hemmings, D.P. and Van Straaten, P. (2009) Paleoenvironments and Origin of the Sedimentary Phosphorites of the Napo Formation (Late Cretaceous, Oriente Basin, Ecuador). Journal of South American Earth Sciences , 28, 180-192. https://doi.org/10.1016/j.jsames.2009.02.004
Davies, J.R., Wilson, D. and Williamson, I.T. (2004) Geology of the Country around Flint. Memoir of the British Geological Survey, Sheet 108 (England and Wales).
Akinlalu, A.A. and Afolabi, D.O. (2018) Borehole Depth Determination to Freshwater and Well Design Using Geophysical Logs in Coastal Regions of Lagos, Southwestern Nigeria. Applied Water Science , 8, Article No. 152. https://doi.org/10.1007/s13201-018-0798-3
Gómez-Escalonilla, Diancoumba, O., Traoré, D.Y., Montero, E., Martín-Loeches, M. and Martínez-Santos, P. (2022) Multiclass Spatial Predictions of Borehole Yield in Southern Mali by Means of Machine Learning Classifiers. Journal of Hydrology : Regional Studies , 44, Article ID: 101245. https://doi.org/10.1016/j.ejrh.2022.101245
Kariuki, D.W. (2021) Borehole Geology and Hydrothermal Alteration Mineralogy of OW-807A, Olkaria Geothermal Field, Reports 2021 (10). United Nations Education-al, Scientific and Cultural Organisation.
Kovalevsky, V.S., Kruseman, G.P. and Rushton, K.R. (2004) Groundwater Studies: An International Guide for Hydrogeological Investigations. IHP-VI Series on Groundwater, No. 3. UNESCO.
Raji, B.A. and Alagbe, S.A. (2000) A Topo-Geochemical Sequence Study of Groundwater in Asa Drainage Basin, Kwara State, Nigeria. Environmental Geology , 39, 544-548. https://doi.org/10.1007/s002540050465
Zaki, M.M., Chen, S., Zhang, J., Feng, F., Khoreshok, A.A., Mahdy, M.A., et al . (2022) A Novel Approach for Resource Estimation of Highly Skewed Gold Using Machine Learning Algorithms. Minerals , 12, Article No. 900. https://doi.org/10.3390/min12070900
Simoni, M.U., Drielsma, J.A., Ericsson, M., Gunn, A.G., Heiberg, S., Heldal, T.A., et al . (2024) Mass-Balance-Consistent Geological Stock Accounting: A New Approach toward Sustainable Management of Mineral Resources. Environmental Science & Technology , 58, 971-990. https://doi.org/10.1021/acs.est.3c03088
Adekeye, O.A. and Akande, S.O. (2005) Mineralogical and Geochemical Studies of Phosphorite Nodules in the Dange Formation Sokoto Basin, Northwestern Niveria. Journal of Mining and Geology , 40, 101-106. https://doi.org/10.4314/jmg.v40i2.18815
García-Rincón, J., Gatsios, E., Lenhard, R.J., Atekwana, E.A. and Naidu, R. (2024) Advances in the Characterisation and Remediation of Sites Contaminated with Petroleum Hydrocarbons. Environmental Contamination Remediation and Management, Switzerland. Springer.
Hossain, M.E. and Islam, M.R. (2018) Drilling Engineering Problems and Solutions: A Field Guide for Engineers and Students. John Wiley & Sons, 627. https://doi.org/10.1002/9781118998632
Kennedy, W.J. and Garrison, R.E. (1975) Morphology and Genesis of Nodular Phosphates in the Cenomanian Glauconitic Marl of Southeast England. Lethaia , 8, 339-360. https://doi.org/10.1111/j.1502-3931.1975.tb00940.x