4D SEISMIC FEASIBILITY STUDY, IN SIENNA, WEST DELTA DEEP MARINE, OIL FILED

Abstract

4D (time-lapse) seismic has become a powerful technology for oil companies to manage their reservoirs. The use of 4D technology is obviously a major investment for oil companies. time-lapse seismic has been proven to be very effective for monitoring not only gas production but also injection process. The process of gas production causes variations in reservoir parameters such as fluid types, fluid saturationand pressure and reservoir thickness and thus changes seismic properties of saturated reservoir rock. Therefore, it is crucial to the success of 4D seismic projects to make a feasibility study determining how we can properly plan 4D seismic surveys for a reservoir under consideration. Determiningthepetrophysicalparameters (porosity,effective porosity, hydrocarbon and water saturation,shale content)forsienna reservoirs rocksusing conventional logging tools(Gammaray,Density,Neutron, Resistivity) in two wells andstudy of the lithology and clay mineralogy of sienna reservoir through Thorium ,photo electric effect, potassium, neutron-density and photo electric effect-densitycrossplots was done. AVO simultaneous inversion inverts pre-stack seismic into P-wave velocity (Vp), S-wave velocity (Vs) and density (ρ). The products of AVO simultaneous inversion can be modeled in the static 2D models. The rock physics model can explain variations in reservoir parameters using the changes in seismic properties several theories link seismic properties of reservoir rock to pore spaces, pore fluids, effective pressure and other reservoir parameters. It is primarily based on core measurements and well logs (1D point model)andAVO inversion product (2D model). The fluid substitution model used to detect the change of the water saturation in the seismic parametersusing Gassmann’s equation and the friable sand model used to detect the change of the pore pressure in the seismic parameters using the Hertz-MindlinandlowerHashin-Shtrikamnequation.