Fracture detection using conventional well logging in carbonate Matulla Formation, Geisum oil field, southern Gulf of Suez, Egypt

Abstract

The non-availability of the advanced tools such as FMI and Borehole Televiewer has led to the use of conventional well logging methods in the examination of potential fractures and ultimately help in reservoir characterization and development. This study uses the said conventional well log data for fracture detection in the Upper Cretaceous Matulla Limestone Formation in the Geisum oil field, southern Gulf of Suez province, Egypt. Different applications have therefore been integrated together, which include the Secondary Porosity Index (SPI) with tri-porosity crossplot (M–N), the natural gamma ray spectroscopy (NGS), the Dual Laterolog–MSFL logs separation, the litho-density and compensated neutron logs and the Variable Density log (VDL), which is based on the responses of the compressional and shear waves in front of fractured zones. Good secondary porosity is prevalent in the Matulla Formation with SPI values reaching maximum values of 21.5 and 15.1% in the studied wells. Three and six fractured zones have been recognized in Geisum A-2 and Tawila N-1 wells, respectively, based on SPI logs. Several of these proposed zones are supported by other tools such as NGS, photoelectric (Pe), and VDL and fracturability Index (FI). This integrated method using various conventional well log has produced results suggesting great probability in fracture identification in the carbonate Matulla Formation.