Sedimentary and electrofacies analysis using MRGC Method in the Bangestan Reservoir of Ghalea-Nar Oil Field, SW Iran

The study of electrofacies is a useful petrophysical analysis method in oil-well exploration and evaluation of reservoir characteristics, particularly when the wells lack actual geological data. In order to interpret the electrical facies of the Bangestan group in Ghalea-Nai oil field, three surface sections were chosen and studied for petrographic and petrophysical features. This resulted in the identification of seven microfacies including: wackstone-wackstone, wackstone, sponge (spongy) spicule oligosteginid, bioclast wackstone-packstone, benthic foraminifera rudist wackstone-packstone, peloidal bioclast packstone-grainstone, peloidal microbioclast packstone-wackstone, pelagic foraminifera wackstone-packstone and oligosteginid wackstone-packstone. Porosity percentages and high quality lithofacies of the Bangestan reservoir were identified by "Geolog software", using petrographic data including: neutron, sonic (sound) and resistivity logs on predominant lithology. Based on these results, and also using of lithology determinant intersecting logs, the major identified lithologies are: limestone, dolomite and limestone with minor amounts of dolomite. Based on these results the identified porosity percentages varies between well. No. 3 with 18% (the highest porosity), well No. 2. with about 10% and well No. 4 with 6% (the lowest porosity). The sedimentary microfacies conforming to high quality reservoir were recognized based on electrical investigation and using of MRGC clustering method. This microfacies which belong to Ilam-Sarvak formations are represented by bioclast peloidal packstone-grainstone and sponge spicule oligosteginid packstone-wackstone, respectively.