Saving and cutting costs and time in oil exploration procedures has long been a major concern in the industry. As a result, magnetometery approaches can satisfy this need to a great extent. Accordingly, by monitoring the magnetic field and its variations in the Karanj oil field while excluding other distracting elements, an attempt has been made to examine the influence of this field in forming magnetic patterns. A magnetometric instrument was used to measure the requisite distance in the form of north-south profiles. According to the findings of this study, the reservoir rock of this oil field has a northwest to southeast orientation, and there is a probability of a northeast to southwest corrosion fault in this reservoir. This corrosion fault most likely caused a reservoir discontinuity, preventing the gas injection from increasing the pressure and thus increasing the harvest.