PORE-CONNECTIVITY BASED PERMEABILITY MODEL FORCOMPLEX CARBONATE FORMATIONS

摘要

The Coates and SDR models for deriving permeabilityfrom NMR T_2 distribution data are based primarily onpore-body sizes and are thus more valid for rocks wherea good correlation between pore-body-size to porethroat-size exists, a characteristic not observed in manycarbonate rocks. In the paper, we describe a modifiedCoates permeability model which takes into account thepore connectivity in carbonates. The model isapplicable not only to vuggy carbonates but also isapplicable to formation rocks that contain abundantmud and/or intragranular porosities. An attempt wasmade to relate the carbonate formation depositionalenvironments and post-depositional diageneticprocesses with the pore-connectivity parameter used inthe modified permeability model, using core NMR,thin-section, and routine core analysis data. Exampleswere shown to use core, formation multi-test, or imagedata to estimate the pore-connectivity parameter andconsequently, improve the accuracy of permeabilityestimation for complex carbonate formations wheremultiple facies present.