ENHANCED AVO USING LAMÉ PETROPHYSICAL FLUID STACKS PARAMETERS FOR GAS DETECTION IN SANDSTONE OVER AN X FIELD, NIGERIAN NIGER DELTA
Journal: Acta Chemica Malaysia (ACMY)
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Here we demonstrate the separation of gas sand from surrounding shale using Lamé petrophysical parameters; , μ and μ where other rock attribute fails to give such clear distinction. Gather stacks (near and far) were generated to improve fidelity of pre-stack seismic. AVO models were generated then combined and inverted with the Seismic gathers to generate Impedance volumes (Zp and Zs) which were transformed to volumes of the Lamé attributes. Results of this method on the logs and pre-stack seismic gathers show significant improvement in DHI detectability over the conventional analysis based on Vp/Vs or Zp, Zs, variations. The results show that moderate to high values of μρ were indicative of clean sands and lower values of λρ and μ (<1) are indicative of high porosity and therefore high reserves in place, in this case gas. The good correlation of the results of the λρ and μ inversion volumes with those of rock physics analysis observed at the well provided confidence in our interpretation of a prospect away from the well thereby leading to discovery of another potential field in the region.