Effectiveness Evaluation of Carbonate Fractured-Porous-Vuggy Reservoirs through Integrated Wireline Logging Data

The carbonate reservoir, characterized by developed fractures, dissolution pores, and cavities, exhibits complex storage spaces and strong heterogeneity, making the identification and evaluation of reservoir effectiveness crucial. This paper addresses the challenges in recognizing and assessing effective reservoirs in complex carbonate rocks, summarizing the well-logging response characteristics of fractured-porous-vuggy reservoirs and effectiveness identification based on geological, logging, and testing data. For the evaluation of different reservoir types, a combination of various well-logging data is selected for comprehensive evaluation. For fractured reservoirs, core data and acoustic/electrical imaging logs are used to identify fracture attributes, while dual laterolog resistivity are employed to calculate fracture aperture, fracture porosity, and permeability. Specifically, a new equation for calculating fracture permeability is established for reservoirs with medium-dip fractures. For fractured-vuggy reservoirs, sensitive factors correlated with hydrocarbon production—such as the difference between deep and shallow laterolog resistivities, the standard deviation of electrical imaging porosity spectrum, Stoneley wave attenuation coefficient, and far-detection reflection coefficient—are optimized to construct a comprehensive physical property index, thereby identifying effective reservoir intervals. For porous carbonate reservoirs, the Thomeer method is selected to classify reservoir quality, and the KNN algorithm is applied to establish correlations with conventional log to evaluate reservoir effectiveness. The above integrated solutions for different reservoir types can effectively address the challenges in reservoir quality evaluation and enhance the development efficiency of carbonate oilfields.