Understanding Different Mineralization Near Faults and Exploring Far Field Fractures Network Using Full Logging Suite in Khuff formation- The Case Study from Offshore, UAE

Abstract The Khuff formation of the United Arab Emirates, is a deep-seated reservoir with temperature exceeding 300 degF and it is characterized as a very dense and fractured unconventional reservoir. Khuff formations exhibit a very complex mineralogy and stratigraphy along with various stages of diagenetic burial, making it challenging to confidently characterize. A detailed fracture characterization and evaluation of the mineralogy is required to determine the possible source and extent of its occurrence. This paper presents an integrated approach using multiple sources of data to effectively characterize this complex unconventional reservoir. Standard reservoir properties were determined by integration of conventional and advanced logs. Detailed mineralogy was characterized using advanced pulsed neutron elemental spectroscopy logs, in combination with X-ray diffraction (XRD) analysis of cuttings, to understand the occurrence of identified minerals seen in this well. In the highly fractured reservoir, it was observed that both natural and induced fractures are present over many intervals, so making fracture analysis challenging. Utilizing high-resolution resistivity borehole image data provided high confidence detailed feature and facies identification that helped in classifying these fractures. Furthermore, integrating high-resolution resistivity borehole image data with acoustic near wellbore reflection images, confidence of fracture strike was increased. This integration enabled confident interpretation of the fracture and fault hierarchy within the Khuff formation, extending our insights up to 80 ft away from the borehole. Additionally, when integrating this information with minerology analysis and core data, it was observed that different fault and fracture zones are associated with different mineralization. This improved the understanding of the relationship between fracturing and faulting and mineralization, by comparison of detailed facies analysis to tectonic events: in particular, it was observed that thick anhydrite deposits correspond with deformation on internal argillaceous carbonates during compaction. This case study demonstrates the synergistic integration of various log measurements and data sources to confidently characterize formation properties, including fault-fracture network, mineralogy, and facies of the Khuff formation. By doing so, we gain a clear understanding of the formation in this specific area of the field We propose that this methodology can be applied to other similar complex carbonate formations to aid in characterizing their properties.