CORE AND LOG DATA INTEGRATION THE KEY FOR DETERMINING ELECTROFACIES

摘要

The key for determining electrofacies is core and log data integration. Recognition of electrofacies in a wide variety of depositional environments can be achieved through inductive and deductive methodologies. In two different fields located in Argentina and Venezuela, open hole logs (spontaneous potential, gamma ray, caliper, shallow-medium and deep resistivities, neutron, density, sonic, photoelectric factor and nuclear magnetic resonance) were calibrated according to the lithological variations described in the cores. The potential capability of multivariate analysis in distinguishing each electrofacies was analyzed based on recognition of geological facies within the core samples. K-means cluster analysis in n dimensions was used to define electrofacies which were entirely associated with the facies observed in the core samples. Encouraging results were obtained after applying such techniques in eolian sand dunes and interdune deposits, mouthbars, distributary channels, meandering and braided deposits. Furthermore, porosity - permeability relationships were established according to the defined electrofacies. An example of a 3D distribution of the electrofacies performed in one field is presented as well. Results reveal the usefulness of applying this methodology for supporting reservoir characterization independently of the depositional environment.