Abstract
Characterization of complex sand reservoirs in deepwater of Niger Delta was carried out through petrophysical and rock physics evaluation of well log data from three wells. Petrophysical analysis to determine clay volume, porosity, lithologies, and hydrocarbon saturation were made. Rock physics was studied in a velocity-porosity plane to analyze the influence of depositional and diagenetic features on the reservoirs. Cross-plots of different elastic parameters, using linear regression and cluster analysis, were generated for lithologic and fluid fill identification and to differentiate between the hydrocarbon bearing sands, brine sands, and shale. Variance attribute was extracted on seismic time slice in order to image the complex sand distribution in the area. Three reservoirs of turbidite origin were identified within the upper fan to lower fan area. Petrophysical results revealed gas bearing reservoir units with less than 20% shale volume and porosity of 25-31%. Lambda-Mu-Rho (LMR) cross-plots for the reservoirs show gas saturated data cloud and trend. Ratio-Difference (R-D) cluster analysis of elastic rock properties shows a distinct trend and data cloud that represents lithofacies units and fluid fills. The study concludes that the reservoirs simulated contact cement and friable models with properties that ranged from highly porous, well sorted and poorly consolidated sand to fairly sorted and highly cemented sands. The results provide a model that increases the possibility of finding reservoir sand while mitigating the risk involved in finding hydrocarbons. Keywords: Rock Physics, Petrophysics, Deepwater, Reservoir, Niger Delta, Cross-plot http://doi.org/10.35180/gse-2019-0009
Highlights
Deepwater and Ultra Deepwater exploration in Niger Delta was heralded in 1990 with the maiden acquisition of two dimensional seismic data offshore with the sole aim of investigating the hydrocarbon potential of the area [1]
This may not be unconnected with the fact that deepwater clastics and turbidites systems in the deepwater Niger Delta are associated with diapiric structural evolution and complex sand distribution [5], [6], [7], [8]
The study by [11] reported that sandstones and shales in siliciclastic formations have been observed to deform differently at specific burial depth. This implies that rock physics analysis of critical changes in the gross rock rigidity and incompressibility can be used to discriminate between lithofacies and fluid content in siliciclastic depositional setting like the deepwater Niger Delta[12],[13]
Summary
Deepwater and Ultra Deepwater exploration in Niger Delta was heralded in 1990 with the maiden acquisition of two dimensional seismic data offshore with the sole aim of investigating the hydrocarbon potential of the area [1]. The study by [11] reported that sandstones and shales in siliciclastic formations have been observed to deform differently at specific burial depth This implies that rock physics analysis of critical changes in the gross rock rigidity and incompressibility can be used to discriminate between lithofacies and fluid content in siliciclastic depositional setting like the deepwater Niger Delta[12] ,[13]. This study is focused on integrating petrophysical analysis, seismic attribute and rock physics responses for lithofacies identification and fluid fill discrimination in order to reduce geological risk and uncertainty associated with predicting complex deepwater reservoirs and lithofacies in the offshore Niger Delta. The results of this study will aid reservoir characterization and conceptual geological modelling of the study area which will in turn aid the direct prediction of hydrocarbon sands
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
