APPLICATION OF POST STACK AND PRE STACK ATTRIBUTES, AND AVO (AMPLITUDE VARIATION 4. WITH OFFSET) IN CARBONATE RESERVOIR

Abstract

In carbonate reservoir rock types which mainly include limestone, dolomite, grainstone, reef limestone, etc., spaces form throughout the entire deposition process and, during each subsequent geological time, the dissolubility and instability of carbonate reservoirs make the evolution of their pore spaces complicated. Therefore, the carbonate reservoirs have complicated pore structures and strong heterogeneity, which is difficult to describe (Abriel, 2009). As an improvement of carbonate reservoir prediction and description precision, the corresponding rock physics model and fluid substitution method have been the keystones and difficulties in geophysical research (Sayers, 2008). The Gassmann equation (Gassmann, 1951) based fluid substitution method is the most widely used fluid substitution method in industry, but it does not consider different pore types effect. In the present work, the Gassmann Equation has been used to model AVO responses in carbonate reservoir in different scenarios, as far as porosity and pore fluids are concerned. A standard set of results has been arrived at, showcasing the typical changes that are exhibited in the AVO gathers, when a carbonate reservoir is fluid replaced with pure-oil and pure gas respectively. Further on, attribut volumes, inversion volumes, and LR vs MR crossplots have also been utilised in the same region for delineating reservoir zones in the carbonate reservoirs.