الملخص الإنجليزي
Carbonate reservoirs are significant contributors to oil production in the Middle East, accounting for approximately 70% of the region's oil and gas reserves. These reservoirs are inherently heterogeneous and present challenges for secondary and tertiary recovery due to their complex depositional environments, diagenetic alterations, and variable fluid properties. Water flooding has emerged as the most successful oil recovery technology for these reservoirs, producing over two-thirds of the total oil production in the Middle East.
The Natih C formation, a tight, naturally fractured carbonate reservoir, is a significant hydrocarbon contributor but poses exploitation challenges due to its low permeability and intricate fracture networks. Currently, the field operates with a line drive water flooding strategy using vertical wells. However, production has fallen short of the Field Development Plan (FDP) projections due to common carbonate reservoir challenges, such as early water breakthrough, poor injectivity, and suboptimal areal and vertical conformance. Published studies indicated that horizontal wells, with their larger reservoir contact area and ability to reduce pressure differentials near the wellbore, can mitigate these issues by targeting oil-rich zones and minimizing water production.
This study examined the effectiveness of water flooding-based field development with horizontal wells in the Natih C carbonate reservoir in northern Oman through comprehensive dynamic modeling using a commercial reservoir simulator. In addition, the study assessed the impact of well orientation (perpendicular vs. parallel to the fault) on production profiles and evaluated the economic viability of the planned development. The results demonstrated that new horizontal wells drilled perpendicular to the fault (NE-SW) outperformed those parallel to the fault, achieving better oil cumulative of 1.264 MMm³ which added a recoverable volume of around 0.618 MMm³. Wells oriented parallel to the fault experienced higher water flow due to structural dips towards the southeast, while perpendicular wells benefited from more uniform liquid flow and consistent reservoir properties.
Economically, wells drilled perpendicular to the faults provided the highest value, with superior NPV, VIR, and UTC metrics compared to their parallel counterparts. These findings underscore the importance of strategic well placement and orientation in optimizing hydrocarbon recovery and enhancing the economic viability of reservoir development projects in carbonate formations.
