Customer Challenge
Following a promising Toca discovery, the urgent need for a fast-track development study emerged. The Toca bioclastic carbonates, formed along the shorelines of a deep anoxic rift lake and organized as gravity flows to the basin, share lateral equivalence with the highly prolific Marnes de Pointe-Noire member source rock. However, the Toca carbonates present a myriad of facies variations and a complex, spatially diverse diagenetic history. Interestingly, the discovery well showed no indication of a water leg, adding to the unique challenges of this venture, as no successful Toca development had been achieved in Congo.
Solution
To comprehensively understand the reservoir’s properties, a meticulous petrophysical evaluation was conducted, delving into lithology, net pay, and fluid properties. Logs, conventional and special core analysis, formation pressure, and fluid sampling played integral roles in this detailed assessment. Additionally, the team employed a least squares minimization method to determine a minimum free water level by comparing a reference bulk volume of oil from well logs with a bulk volume calculated from capillary measurements-based saturation height function.
Outcome & Value Delivery
Our dedicated and rigorous approach, combining a physics-based multimin method with invaluable core data, yielded remarkable results. Not only did we achieve a reliable assessment of this mixed-mineralogy play, but we also redefined reservoir intervals with an impressive +10% increase in net reservoir thickness. Furthermore, the integration of core permeability with mobilities resulted in a robust permeability model in this heterogeneous environment, requiring only a 3x multiplier compared to well test measurements. Moreover, our careful review of available log data on this key well identified cost optimization opportunities for future wells, where spectroscopic logs proved pivotal, unlike DTS and NMR.
