Application of Improved Dual-mineral Model in Logging Evaluation of Continental Tight Reservoir in the Northeast Sichuan Area

In Da'anzhai member of northeastern Sichuan Basin,there developed mudstone,sandstone and coquina,the main reservoir lithology was coquina.The reservoirs in the studied area were reservoirs with extra-low porosity,extra-low permeability,micro-porosity and micro-fractures,they were complex pore structure and strong heterogeneity.In the traditional dual-mineral model,porosity logging curve was used to quantitatively calculate mineral composition and porosity,but the results were inconformity with the logging results and core analysis results.An improved dual-mineral model was proposed,which used resistivity logging curve that was sensitive to lithology to determine the contents of minerals,matrix porosity was calculated according to mixed mineral skeleton.The mineral composition and porosity calculated by the improved dual-mineral model are consistent with logging results and core analysis results.So it is an effective and practical method for logging interpretation of reservoirs with micro-porosity and micro-fractures and complex lithology in the area.