Determination of the heterogeneity index based on petrophysical and image logs in the Sarvak reservoir of an oilfield located in the Dezful Embayment

In this study, the heterogeneity of the Sarvak reservoir in an oil field located in the Dezful Embayment was studied. The occurrence of heterogeneity is primarily attributed to various geological factors in carbonate formations, including the Sarvak Formation, resulting in significant impacts on petrophysical and other reservoir characteristics. The heterogeneity index can be calculated using conventional petrophysical logs or advanced FMI image logs from petrophysical point of view. The heterogeneity index was calculated in this study using two methods across two wells. The index was measured using conventional methods such as Dykstra Parsons coefficient, Lorenz coefficient, and coefficients of variations of porosity and permeability based on conventional logs. In contrast, the second method used FMI logs to obtain the index by calculating the sort index as a measure of heterogeneity. Based on this study, there is a high correlation coefficient between the coefficients of variations of porosity and permeability and the Lorenz coefficient with the image log index in the two studied wells (up to 60%). This study indicated the LSB2 zone has the lowest heterogeneity value while the LSG zone has the highest heterogeneity value in this field based on sort index of FMI log. The heterogeneity found in this reservoir is primarily due to diagenetic processes.