Identification of electrical and petrophysical rock types based on core and well logs: Utilizing the results to delineate prolific zones in deep water sandy packages from the Shah Deniz gas field in the south Caspian Sea basin

Abstract

The construction of a geological model using geostatistical simulation methods plays a key role in reservoir characterization. One of the most important parts of the reservoir studies is the discovery of high reservoir quality areas which in turn are dependent on the depositional properties of reservoir formations. The main properties of rocks are usually defined by descriptive studies in the field or on cored intervals (lithofacies) and in more detail by laboratory studies (petrofacies and microfacies). Considering that the core data are not available in all drilled wells, the main focus is on well log data which exist in all wells, continuously. In the current study, with focus on deep sandy reservoir deposits in the southern area of the Caspian Sea, reservoir rocks were characterized based on the integration of the results from core description, thin section studies and petrophysical analysis of well logs in one of the sandstone fields with five members. Balakhany and Fasila sand members are the deepest sandstone members of the field. First petrofacies were identified based on core description and thin section studies. In the next step, the electrical facies and electro-petrophysical facies were investigated using a combination of log data and petrophysical parameters based on Multi-Resolution Graph Base Clustering (MRGC) method. The results from this stage in combination with identified petrofacies were used for the construction of a reservoir static model. Finally, a 3D model of reservoir facies was obtained in each reservoir zone by using variogram analysis and sequential indicator simulation (SIS). The constructed facies model suggests that the high reservoir quality facies are well distributed in the sandy package 3 (SP3) and Fasila B.