Copyright © Adekunle O. Sofolabo, Alexander Nwakanma. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. International Journal of Advanced Geosciences, 10 (1) (2022) 28-40 International Journal of Advanced Geosciences Website: www.sciencepubco.com/index.php/IJAG Research paper Reservoir characterization using integrated seismic attributes and petrophysical parameters in an onshore field of Niger delta basin Adekunle O. Sofolabo 1 *, Alexander Nwakanma 1 1 Geophysics Research Unit, Department of Physics/Applied Geophysics University of Port Harcourt *Corresponding author E-mail: adekunle.sofolabo@uniport.edu.ng Abstract An integrated approach of reservoir characterization of a field was performed using seismic attributes and petrophysical parameters for the evaluation of subsurface geological features and hydrocarbon potential of an onshore field in Niger Delta Basin. Four reservoir inter- vals were identified within the field wells based on their position within the stratigraphic column, and the reservoir correlation, which was aided using the principle of uniform horizontality, based on the simple rule that sediments are deposited horizontally and basic un- derstanding of sequence stratigraphy. The study revealed that, the four reservoirs were predominantly sand units intercalated with shale within the reservoir units. The petrophysical evaluation revealed the Net to Gross (NTG) values ranges from 79% to 87% within the res- ervoir units, while the effective porosity ranges from 17% to 21%, the permeability ranges between 1307mD to 1678mD across the res- ervoir units, while the water saturation ranges from the lowest of 35% (Reservoir C) to 78% in reservoir D. A total of fifteen faults were interpreted using the seismic data, while the surface maps (Time and depth surface maps) revealed the identified closures which are anti- clinal structures that are fault dependent. The characterization of the reservoir was further enhanced using the seismic attributes (structur- al and stratigraphic) extracted such as Reflection intensity, Sweetness, Variance, Envelope, Instantaneous frequency, Time gain, Trace AGC, Local structural dip, Gradient magnitude and RMS amplitude. The results shows moderate to high sweetness (sweet spots) within the zone of interest, while the Envelope attribute show acoustic impedance contrasts indicating discontinuities, lithology changes and possible present of hydrocarbon (Bright spots). The variances and gradient magnitude enhanced the signal to map out discontinuities caused by faults and fractures which are signature that enabled delineation of the zone. The integrated approach validates the lithology discrimination of the elastic properties from the well logs and its effectiveness in optimizing and proper understanding of the subsurface, thus identifying and unmasking hidden features within the reservoir (probable bypass) in the field. The study has revealed that the inte- gration of seismic attributes with petrophysical parameters is a better characterization method for fluid and lithology discrimination of a field in any given reservoir study. Keywords: Bright Spots; Root Mean Square; Reservoir Characterization; Seismic Attributes; Stratigraphic Column. 1. Introduction Surviving the current global oil crises, most oil and gas companies needs advance technology for a very careful and thorough evaluation of information obtained from the subsurface; evaluation of such information has gone beyond the use of well logs only but integrating the information analysis of conventional 2-D and 3-D seismic data. The information extracted from seismic data includes various seismic attributes which has proven to be a very useful tools in exploration and development of possible prospects. Seismic attributes extract- ed/obtained from seismic data have helps to better visualizes and quantify subsurface structures/features for interpretation purposes. Thus, extraction of seismic attributes from seismic data can therefore be said to be a better analysis technique needed to improve the accuracy of interpretations and predictions of hydrocarbon prospects as well as field development. Seismic attributes allow the geoscientists to interpret faults and channels, recognize depositional environments and unravel structural deformation history. They are also useful in checking the quality of seismic data for artifacts delineation, seismic facies mapping, pro- spect identification, risk analysis and reservoir characterization. Seismic attributes provide a link between petrophysical properties and seismic data of the reservoir, which are directly or indirectly related to rock properties of the field. Seismic attributes evaluation involves the analysis of the subtle changes in properties of particular subsurface reflections in determination of the rock properties, including fluid content which assist in the creation of different geological models in a faster and reliable way (Taner, 1979). Seismic attributes have emerged to transform subjective and experienced based interpretation process into something less tedious and more objective. The use of seismic attributes has passed through periods of great proliferation and enthusiasm contrasting with moments of disuse and lost in credi- bility (Azevedo et al., 2012). Amongst the first seismic attributes developed relative to the 1-D complex seismic trace includes envelope amplitude, instantaneous phase, instantaneous frequency, apparent polarity and acoustic impedance. Other attributes commonly used are coherence, azimuth, dip,