Optimizing Production in Jurassic Tight Carbonate Reservoirs by Strategically Positioning Wells Within Prime Carbonate Reservoir Facies Through Integration of Source-Less NMR While Drilling and Deep Azimuthal Resistivity Tools

Abstract The Jurassic Marrat formation in West Kuwait is characterized as a dense and varied carbonate reservoir, where its petrophysical traits hinder accurate predictions of reservoir properties. Drilling a new well presents operational risks; thus, the use of LWD triple combo is avoided to prevent environmental concerns and manage costs. In its place, the combination of LWD-NMR and Deep Azimuthal Resistivity tools is identified as the ideal approach for assessing the formation and optimizing well placement to target the highest quality reservoir. The advanced While Drilling nuclear Magnetic Resonance tool is employed for precise porosity measurements due to its independence from lithology. The T2 distribution serves as a direct indicator of both porosity and permeability. The DAR is an azimuthal propagation resistivity tool that significantly minimizes the risk of misplacing the wellbore during the drilling of extended reach and complex 3D horizontal wells. Although the Marrat reservoir typically exhibits high resistivity, its porosity levels are not always optimal. This creates additional challenges for geosteering operations when relying solely on gamma and resistivity logs. By integrating LWD-NMR with DAR, operators can enhance reservoir contact and optimize production from the highest quality reservoir zones. The drilling plan was adjusted in real-time to ensure a successful landing within the target zone; After successfully landing the well at a 90-degree inclination based on the NMR and DAR signatures, we continued to increase the inclination angle to 90.5 degrees to carefully slice stratigraphically through the section and access the optimal reservoir zone, before gradually tapering off to 89.3 degrees based on the NMR and DAR signatures to keep the well within the most favorable reservoir facies. During geosteering in the F-11 zone, we observed a decline in porosity from 16 pu to 2 pu as detected by the NMR. In response, we made real-time adjustments to navigate away from the tighter area and direct the well toward the sweet spot within the F-11 zone. The effective integration of NMR and DAR tools led to a successful well landing in the F-11 zone, which shows strong hydrocarbon potential. The production data thus far demonstrate very promising results compared to the offset data.