Petroleum production from oil and gas reservoirs around the world is typically going through a cycle of early life production, production plateau then production decline till abandonment phase is reached. Production optimization is a key process to prolong production from the reservoirs and maximize the hydrocarbon recovery from the targeted reservoirs. Optimization can have several methods and procedures depending on reservoir conditions, characteristics and the objective that the professionals are trying to achieve including drilling infill wells, adjusting offtake from current wells, injecting external fluids to reservoirs and so on. Since optimization involves remarkable expenditures in most of the cases, the options of optimization have to be studied thoroughly via the various methods and tools available in petroleum engineering. One of the recognized tools in oil industry is the use of material balance equations that are fundamentally based on the fact that the initial volume must be equal to the summation of the removed volume and the remaining volume. These calculations can be done by modeling softwares that depend on material balance concept to study optimization and come up with scenarios that fit the conditions of the reservoir, safe to operate and economically feasible for operator. This project studied two cases for brown fields in northeast of Oman producing from, Khufai formation, a naturally fractured reservoir with different petroleum setups. The first case study is producing from Khufai formation with aquifer influx that provides proper drive and pressure support. Through material balance modeling, hydrocarbon volume was modeled and compared with volume scenarios from static geological model and sensitivities that affect the modeling of volumes were considered. Options of optimization via drilling additional wells were investigated and numbers of wells to be drilled were decided along with prediction of recovery and anticipated project generated revenues. The second case study is producing from Khufai formation as well but with different drive mechanisms and with absence of any water influx where the reservoir is going through severe pressure depletion not allowing continuity of production from the reservoir. Similar to the first case study, hydrocarbon volumes were modeled and sensitivities that are related to this particular case were modeled. Volumes were also compared to those from static geological model. Optimization options through enhancing reservoir pressure were studied using material balance models. Different sensitivities were considered to cover the potential uncertainties in the production prediction which is a cornerstone for the optimization feasibility. All modeled options with their sensitivities were economically evaluated and screening of optimum options was done by taking into account the maximum net present value.