Effect of Shale on CO2 Sequestration: A PetrophysicalAnd Geochemical Assessment in G-Oil Fieldof The Niger Delta Basin

This research was designed to analyse the effect of Shale in CO2 storage process ‎petrophysically and geochemically within the G-Oil field in the Niger Delta Basin. Eight ‎wells were profiled with 18 reservoirs delineated using Interactive Petrophysics software. ‎Results show that Total porosity (∅t) within the range of 0.144-0.288 is higher than ‎Effective Porosity (∅eff) which ranged from 0.142-0.275. Archie Water Saturation values ‎‎(0.14-0.467) are higher than those of the Indonesian model (0.131-0.457). Permeability (k) ‎values ranged from 181.01mD to 7942.091mD. Shale Volume (Vsh) ranged from 0.005-‎‎0.322 representing ‘clean/shaly sand’, with 13 reservoirs having ‘shaly sand’ lithology. ‎Shale is petrophysically confirmed with a mean value of ∅t (0.24) higher than ∅eff (0.228), ‎and Archie Sw (0.352) being higher than Indonesian Sw (0.31). A high mean value of k ‎‎(1780.941mD) confirms the existence of highly connected pores for CO2 movement. Mean ‎Vsh is 11.7%, indicating shaly sand lithology. Geochemical interaction of this shale with ‎Dihydrogen Carbonate produced from the CO2/H2O reaction will increase ∅eff and k in the ‎presence of adequate Sw (0.31). An increase in values of ∅eff and k implies an increase in ‎storage capacity of the reservoirs such that connected micropores increase while ‎unconnected nanopores decrease.