Structural interpretation and petrophysical approach for subsurface fracture identification of Joya Mair area, NW-Himalayas, Pakistan

Authors: PALWASHA SHAHZAD RATHORE, MUHAMMAD ARMAGHAN FAISAL MIRAJ, MUHAMMAD BILAL MALIK, SHER AFGAN, RANA FAIZAN SALEEM, SHAN SHAHZAD, IRZA AKHTAR

Abstract: Identification of fracture zone is a challenging task without the image log data. There are many brownfields around the world where the image log has not been acquired; therefore, there must be an alternative way of fracture identification. In this paper, a conventional log response technique for fracture delineation has been discussed. The study area lies in the Upper Indus Basin of Pakistan, which is sub-divided into the Kohat and Potwar basins. Minwal-X-1 of Joya Mair area, which lies in the Potwar Basin, is selected for this purpose. Eocene limestone units are formed due to fracture porosity. The objective of the current research is to interpret the subsurface structure and to identify the fractured zones with the help of conventional well log responses. Subsurface seismic interpretation reveals that the area has a triangular zone structure formed as a result of compressional tectonics. Well log responses indicate the presence of the fracture zones in the Chorgali Formation and Sakesar Limestone of Eocene age in Minwal-X-1 well. Few zones, which can be possible fractured zones, in these formations were marked by analyzing the conventional log responses and secondary porosity index (SPI). All the conventional log responses and cross plots support the presence of fracturing in Eocene limestones. The technique of identifying fractured zones with the help of conventional log responses is beneficial for researchers as FMI, and core data are very expensive and not available to everyone. Therefore, the convention log-based approach can be helpful where image log data (FMI) is not available.

Keywords: Fracture delineation, seismic interpretation, petrophysical analysis, triangular zone, compressional tectonics, FMI

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