Microbial Carbonates and Dolomite Reservoir Sweet Spotting in the Middle Marrat Utilizing Traditional Core Work Supported by AI

Abstract In carbonate reservoirs, sweet spots are governed by the interplay of depositional, diagenetic, and structural-geomechanical processes. To support Kuwait Oil Company's (KOC) goal of ramping up gas production from the North Kuwait Jurassic Gas Asset (NKJG), the best reservoir zones need to be identified and targeted with drilling & completion strategies adjusted to the sweet-spot type. We present an integrated core-based workflow to define and delineate sweet spots in the tight gas reservoirs of the Jurassic Middle Marrat Formation. A multi-scale approach was applied, combining Shell's expertise in carbonate geology, petrophysics, and machine learning, utilizing advanced tools to reframe sweet spot identification. The starting point was a well-established sequence stratigraphic framework including well-defined gross depositional environment maps for each key stratigraphic interval. This study focused on identifying sedimentological and diagenetic sweet spots within this framework using core- and log-based data. The sweet spots were also linked to paleotopography reconstructed back to the time of deposition. Traditional sedimentology was enhanced using AI-based core interpretation, integrated with wireline logs and production data to pinpoint high-permeability zones. Within the reservoir zone of interest two main sweet spots were identified as potential storage and flow units respectively. These sweet spots are characterized by patchy backshoal microbial build-ups (thrombolite-dominated) and a continuous, fine-crystalline dolomite layer, both formed within a hypersaline lagoon. The study successfully identified the presence, properties, and spatial distribution of these reservoir sweet spots within the target reservoir zone. This core-based workflow provided recommendations on how to optimize horizontal well placement, guide infill and appraisal drilling, and inform well-path and completion design for the reservoir zone of interest.