Tight carbonate reservoir characterization based on the modified rock physics model

Because tight carbonate reservoirs have outstanding potential of reserves and economic benefits, it is significant to recognize their typical geophysical responses using rock physics models. Nevertheless, conventional models are not satisfactory to interpret multi-scale or in-situ observations, since their computational generalization. To enhance the predictive and computational power, this paper derives an upscale rock physics model which includes both modeling and inverting schemes. Its main idea is to study and utilize inherent statistical natures in naturally occurring tight carbonate rocks. Through extending the typical critical porosity model (CPM), our modeling scheme relates pore system to wave propagation and fluid flow responses in dolomite-calcite mixtures. Thus, it can recognize the effect of pore structure changes on velocity and permeability heterogeneity. On the other hand, in terms of deterministic and probabilistic methods, pore systems can be characterized within different scopes of observations. It also allows a model based inverting scheme for data interpretation and correction, according to the statistical comparability between lab measurements and well logs. Therefore, if mineralogy contents and noisy sonic logging curves are available, one can simultaneously obtain the corrected porosity, permeability and velocity curves. In site data tests, predictive power of this model is well demonstrated by the high data consistency.