IOSR Journal of Applied Geology and Geophysics (IOSR-JAGG) e-ISSN: 2321–0990, p-ISSN: 2321–0982.Volume 8, Issue 3 Ser. II (May – June 2020), PP 31-47 www.iosrjournals.org DOI: 10.9790/0990-0803023147 www.iosrjournals.org 31 | Page Petrophysical Evaluation of Hydrocarbon Bearing Sands in “MANIN” Marginal Field, Onshore Niger Delta Eke, I.J 1 and Ideozu, R.U 2 Department of Geology, Federal University of Technology Owerri, Nigeria, Department of Geology, University of Port Harcourt Nigeria Abstract: Wirelinelog was used in the analysis of the reservoir properties of “Manin” Marginal field, onshore depobelt, Niger Delta. The study essentially focused on determining properties such as lithology, depositional environments and petrophysical properties such as shale volume, porosity (Φ), net pay thickness, net to gross ratio and water saturation. Wireline data of four wells namely well 4, well 7, well 5 and well 11 were evaluated by identifying hydrocarbon bearing sands in each of the four wells and then estimating the petrophysical properties for these reservoirs. The evaluated reservoir sand units mapped were laterally continuous with gamma ray log signatures that are basically cylindrical with a fining upward sequence interpreted as a fluvial dominated channel. The environment of deposition was inferred to be between the foreshores to lower shoreface with reservoirs typically showing a consistent aggradational stacking pattern. A total of four reservoir sand units (A-D) were analyzed for petrophysical parameters such as porosity , net-pay thickness, volume of shale (V sh ), net to gross ratio and water saturation (S w ). Porosity within the field ranged from 25.9-31.9%, volume of shale ranged from 0.204-0.430, while water saturation value ranged from 0.015-0.220. Sand A, B and C had excellent porosity values while sand D had moderate porosity value. The petrophysical properties evaluated reveals possibilities of future drilling prospects in the “Manin” field. Key Words: Niger Delta, Petrophysical properties, Reservoirs, Porosity, Environment of Deposition. --------------------------------------------------------------------------------------------------------------------------------------- Date of Submission: 03-06-2020 Date of Acceptance: 18-06-2020 --------------------------------------------------------------------------------------------------------------------------------------- I. Introduction The “Manin” oil field is located onshore with an OML-056 in the Northern Delta depobelt, north- central part of the Niger Delta. It is of extraordinary significance to comprehend the petrophysical properties of reservoir rocks. Exact assessments of certain petrophysical parameters can be produced using wireline logs such as neutron, bulk density and sonic log. Reservoir sands in various depositional situations are described by various sand body shape, size, and heterogeneity; hence this tends to demonstrate that the physical attributes of clastic reservoir rocks mirror the reaction of mind boggling interplay of processes operating in the depositional environments. Likewise, learning of depositional environment of reservoirs through precise interpretation of wire line logs and core data if available allows for a better understanding of reservoir characteristics. A reservoir is said to be commercially productive; if it produces enough oil or gas to pay back its financial investors for the cost of drilling and leaves a benefit. Numerous studies have attempted to provide better knowledge of reservoir frameworks across the Niger Delta basin in order to reduce the time and cost of exploration especially in challenging environments such as offshore areas. Ulasi et al. (2012) integrated core data and petrophysical well log in order to evaluate the reservoir characteristics of Uzek Well in the Offshore Depobelt of the Niger Delta Basin. Eze et al. (2013) used petrophysical well logs to evaluate the reservoirs from about three wells in the greater ughelli depobelts in order to ascertain the qualities of the reservoirs and their depositional environment. Ogidi et al. (2018) carried out an assessment of the petrophysical characteristics of reservoir sands in „OTEBE‟ field using geophysical well logs. In a similar study by Ighodaro et al. (2019) petrophysical properties of a well from the onshore Niger Delta oil field were evaluated using well logs in order to determine the hydrocarbon potential. Kafisanwo et al (2018) used 3D seismic, well logs and Checkshot data to characterize reservoirs and identify prospects in the Onka field of the offshore Niger Delta. The purpose of this work was to carry out petrophysical evaluation of hydrocarbon bearing sands in “MANIN” Marginal Field, Onshore Niger Delta in order to determine lithology, delineate depositional environment from gamma ray log motifs and establish the depositional origin and integrate it with the reservoir petrophysical properties. The field is located in the OML-056 in the northern region of the onshore Niger Delta. A total of four wells were drilled in the “Manin” field (figure 1.1).