Carbonate fractures from conventional well log data, Kometan Formation, Northern Iraq case study

Abstract

The Borehole Acoustic Televiewer, Formation Micro scanner (FMS), Formation Micro-Imager (FMI), and Electric Micro Imaging (EMI) are the most qualified approaches to fracture identification. Still, they are more expensive and only give images at specific intervals. Conventional well log tools can be identified without interval limitations. This study aimed to demonstrate the ability of the Conventional well logging tools to identify fractures in the Upper Cretaceous Kometan Formation in the Northern part of Iraq. The study area is located at latitudes 3,922,836.34 N to 3,930,557 N and longitudes 448,350.78E to 417772E for the well of Kirkuk 216 (K216) and Khabbaz 40 (Kz40), respectively. Quantitative interpretations like secondary porosity index and qualitative are the total porosity-sonic porosity cross-plot, caliper log, total gamma-ray log, and porosity logs (neutron, sonic, and density log) have been used to identify fractures in the studied formation. Some subsurface rock samples (spectral gamma ray) and outcrop observations were also used to validate well log data results. Good secondary porosity (fractures) has been Identified from the Secondary Porosity Index (SPI), which is reached a maximum value of 17%, and the average is 4% for Kz40. The maximum value is 30%, and the average is 8% for K216. Based on the qualitative interpretations of the available log data, which were validated by subsurface rock samples and observed outcrop sections of the studied formation, it has been concluded that the reservoir quality of the Kometan formation was enhanced due to high fractures in the studied wells.