Perpustakaan Digital ITB

Declining reservoir pressure is a major challenge to the sustainability of gas production in mature gas reservoirs. This study investigates production optimization strategies for the Mnazi Bay Gas Field under declining reservoir pressure conditions using an Integrated Production Modelling approach. The gas field is estimated to contain 1036 Bcf of gas reserves produced from the Miocene reservoir formations. Currently, it operates with five producing wells, MB-1, MB-2, MB-3, MB-4, and MS-1X, at a field production rate of 130 MMscf/d over a contractual period of 16 years. Four optimization scenarios were investigated, including the existing production system, the application of surface compression, the perforation of additional reservoir zones, and the drilling of infill wells, with reservoir performance, well deliverability, and surface production network behaviour analysed using MBAL, PROSPER, and GAP simulation software. However, the existing five-well configuration sustained the target production plateau for only 4.49 years when operated with 2.867-inch tubing and a separator pressure of 1,450 psi, representing only 28% of the contractual target. The optimal production scenario involved reducing the separator pressure to 725 psia, increasing the tubing size to 4 inches, and perforating three additional zones (I, C, and H). This was the only optimization scenario that successfully extended the production plateau by 12.54 years, sustaining production until 28 October 2035 and meeting the 16-year Gas Sales Agreement (GSA) requirement while utilizing existing infrastructure, resulting in lower cost and operational risk compared to drilling four new infill wells. Based on these findings, the operators of the Mnazi Bay Gas Field are encouraged to adopt this optimization strategy to extend the field's production plateau.