Enhancing Reservoir Characterization and Completion Optimization of Jurassic Tight Carbonate Gas Fields in North Kuwait Using High Resolution LWD Imaging

Abstract The Jurassic carbonate reservoirs in North Kuwait have led to the discovery of six significant tight gas fields, covering approximately 1,800 square kilometers with a gross reservoir thickness of around 2,200 feet. These fields represent Kuwait's first free-gas fields, which began early production in 2008. Characterized by dual porosity, these reservoirs predominantly exhibit low porosity and permeability, making fractures critical for effective reservoir characterization and completion optimization by mapping high fracture density zones. Recording wireline logging in highly deviated or horizontal wells within depleted formations presents considerable challenges. issues such as wellbore instability, differential sticking, and mud loss are common when drilling depleted reservoirs in deep high-temperature high-pressure (HTHP)wells in Kuwait. The long-term production has significantly depleted formation pressures, complicating drilling operations and resulting in substantial non-productive time. Consequently, identifying a viable logging solution is essential when traditional wireline logging methods prove ineffective. The upgraded High Resolution LWD Imaging service provides comprehensive 360-degree borehole coverage in a small hole, capturing images with 256 data samples per depth. This extensive data collection facilitates the identification of critical formations features, including fractures vital for effective reservoir management. Furthermore, this technology can be integrated with the Density Imaging service, offering complementary information that enhances interpretation and decision-making processes. The application overview emphasizes several analytical capabilities. Feature classification through dip picking allows for the identification of geological and non-geological features within the images, serving as a foundation for further analyses. Structural analysis focuses on determining structural dip and understanding deformation within complex geological formations. Fracture and fault analysis includes recognition and differentiation between natural and induced fractures alongside fault classification. The upgraded Ultra Sonic imaging service in this tool addresses issues related to heterogeneity, flow barriers, diagenesis, and secondary porosity identification. Geomechanical evaluations involve assessing in-situ stress features, identifying types and causes of induced fractures, and analyzing occurrences of borehole breakout. The deployment of this service occurred in a well with a high deviation angle of 64.5°, necessitating a shift from wireline to washdown logging due to challenges in reaching TD and concerns about differential stuck pipe incidents. The logging operation utilized a 6-inch washdown run with Ultrasonic in both real-time and memory modes at a speed of 100 ft/hr with a rotation rate of 100 RPM. To optimize data collection, the tool was programmed to prioritize bulk density, neutron measurements, caliper readings. Surveys were conducted at each connection for image orientation to mitigate risks associated with differential sticking. The successful implementation of the upgraded High Resolution LWD Imaging tool at KOC not only showcases technological innovation but also establishes a benchmark for future applications in complex drilling environments