Detection of Fracture Using Petrophysical Logs by New Method and it's Corolation with Image Logs

To study of petroleum reservoirs which their productions are function of their fractured system, fractures assessment is necessary and important in oil production optimization and field development. The purpose of this research is recognition of a quick method for identification of fractured zones using petrophysical logs which are handy in all wells, and their effects on porosity and permeability of Asmari reservoir of Balarood oil field. The result shows that although some factors such as lithology and reservoir fluids effects on petrophysical logs, requiring minor corrections to logs by means of mathematical methods such as derivation can be used to determine fractured zones on logs, which show great consistency with image logs and velocity deviation log. Results show that zones of abundant bearing fractures can be easily recognized on first stage of derivation on petrophysical logs. Derivation process of any log is defined as a function for that log. Tectonic information and geological prospective of oil field will have an apparent contribution in identification of fractured zones. In addition, fractures and porous zones have had effective impact on the reservoir rock properties. The results indicated that the production in the Asmari reservoir of this field is a combination of fractures and rock matrix and fracture analysis can be done by using petrophysical logs in old drilled wells without image logs as well. As six logs RHOB, NPHI, GR, DT, PEF, CAL have vital role in petrophysical studies, these six tools are the best logs to diagnosis of fractured zones due to their responses against the fracture along with doing some corrections in these logs.