It is well known that drilling challenges, in addition to fluctuating oil prices and increasing competition for production, can contribute to unscheduled field expenditures exceeding one billion U.S. dollars annually. This study emphasizes the importance of integrating geomechanical principles into petroleum engineering, which includes reservoir, drilling, and production operations. A case study was conducted on one well in Rumaila oilfield, located in southern Iraq, to determine the geomechanical properties of carbonate, sandstone, and shale formations. Stress regimes, elastic, and rock strength properties were analyzed. The results showed the stress regime is a strike-slip regime from the Sadi to Zubair formations. The Tanuma formation exhibits low elasticity and strength properties, indicating optimized mud rheological properties for effective lifting capacity. The MishCR1 reservoir, as a producible formation with high rock mechanical stability, can resist compaction and fault reactivation. Other oil-producible reservoirs (MishMA, MishMB2, MishMB1, Zu1, and Zu2) have moderate geomechanical properties, requiring tailored production rates, pressure management, and enhanced recovery methods to mitigate deformation risks. For sandstone reservoirs (Zu1 and Zu2), gravel packing or chemical stabilization is recommended to sustain reservoir performance and enhance oil recovery. This study presents the need for geo-mechanical insights to optimize petroleum operations and mitigate production risks.