Abstract: The pseudo-characterization of seismic shear wave impedance and velocity ratio on the acoustic impedance in abstruse reservoirs has given rise to obscureness of seismic data juxtaposition such as reservoir thicknesses delineated below quarter of a wavelength (1/4k) and seismic cross plot amphibolies. The aim of this pedagogic is to ruminate and characterize these critical seismic attributes in intricate reservoirs. Materials used are high resolution 3D post-stacked and check shot seismic data, 3 composite well log suites (X1, X2, and X3) and a base map from the X-field in the Niger Delta, Nigeria. Schlumberger-Petrel simulator was used to produce variant cross plots models of critical attributes sensitive to formation fluid saturation and pressure while lithology/fluid contacts were cross plotted with acoustic impedance. Comprehensive results of Vp/Vs against acoustic impedance showed presence of hydrocarbons and water from both wells located in reservoirs HD 5000 and HD 9000. Gas sand with average densities from 2.0703g/cc to 2.1490g/cc exist in well X1 and 2.0809g/cc to 2.1702g/cc exist in well X2. Oil was identified in well X1 in reservoir HD 9000 with density from 2.0577g/cc to 2.1266g/cc. Results of S-impedance against acoustic impedance showed also the presence of hydrocarbon, shales and a wet trend line. These resultant variations of lithology/fluid juxtaposition due to acoustic impedance perhaps located previously hidden gas-water and oil-water contacts at different locations in the reservoirs. It is however recommended that further studies be done on the characterization of these oil/wet trend lines with increased data volume.
Keywords: Reservoirs, wells, acoustic impedance, velocity, juxtaposition, lithology, attribute.