You have no items in your shopping cart.
ABSTRACT
The trend analyses of subsurface petroleum migrations and accumulation systems in Omaki Field in western Niger Delta were analysed using 3-D and 4-D seismic data acquired at different times of productions. The aim is to analyse the mechanism and trend of hydrocarbon migration and accumulation system in Niger Delta. As part of the method, the differences resulting from the acquisition design and other nonproduction related variations must be minimized between the two surveys through crossequalization process. The reservoir parameters were simulated using seismic inversions, geological and geophysical models. The results of the lithological and fluid parameters of the reservoirs showed that the reservoirs are dominantly sand lithology with little shale or silt intercalations. In Omaki_1, the TB400 and TB500 reservoirs revealed the highest average water saturation value of 35% and 45% with average water saturation of 29% and 34% respectively. The TB670 have the least average water saturation and porosity values of 15% and 25% respectively. In Omaki_2, the reservoir showed average water saturation value of 42% and porosity value of 35% while TB240 reservoir, revealed average porosity and water saturation value of 31% and 19% respectively. In Omaki_3, TB100 and TB200 revealed average porosity values of 31% and 28% and water saturation values of 23% and 42% respectfully. In Omaki 4, TB100 and TB200 also maintained average porosity values of 31% and 28% and water saturation values of 27% and 43% respectfully. The effective thickness of the reservoirs was derived using the 3D seismic depth-model which produces the isopach maps profile of the subsurface media. The colour bars indicate the thickening (blue and Pink) and thinning (green and yellow) of the sand bodies. The textural and structural variation of the reservoir sand bodies indicate that the sand thicken basin ward, which is a typical thickening pattern in the Niger Delta Basin and characteristic of transition environment. The results of advanced facies and fluid sensitivity analysis revealed the variation in lithology, fluid saturation and the hydraulic fracture development in the reservoirs. The brittleness of the reservoir is dependent on the facies or lithological fracture index and reservoirs with high fracture index are susceptible to hydrocarbon migration especially when the induced temperature and pressure offset the normal formation pressure. The results of structural analysis using time structure maps indicates that the base showed very strong continuous reflection events with few abrupt terminations and major faults with relative regional extent while the monitor displays more discontinuity and abrupt termination of coherent seismic reflection events probably caused by production related effects. The seismic inversion results analysis revealed the trend of the hydrocarbon migration in the western Niger delta.
