PERIODIC ROUTING OF WELL TECHNICAL SERVICES GROUPS IN OFFSHORE SHARED OIL FIELDS

Production wells in offshore shared oil fields require well technical services. These services are done by two types of well technical services groups: wellhead services and wire-line services. Production wells in offshore shared oil fields require well technical services and the lack of services affects production productivity of oil wells. In fact, due to supply limitations, there are fewer well technical service groups compared to the number of oil wells. Failure to service oil wells by well technical service groups based on a predetermined plan will lead to considerable loss in production performance of oil wells and, hence, higher costs. However, the stopping production process is one of the requirements in giving some services to oil wells and, thus, this leads to greater oil production than the competitor neighbor countries and increasing opportunity cost for us. Therefore, in these conditions, making a balance between servicing with stopping production process and minimizing stopping production is very important. Firstly, a mixed- integer programming model is proposed for the problem considering new applicable and practical features that have not been introduced before. Secondly, algorithms based on Benders and L-shaped exact methods are developed. Moreover, algorithms based on Lagrangian relaxation heuristic method in seven states are developed. Each state involves eliminating some selective constraints of the proposed mathematical model and adding its objective function to obtain the best constraint selection. In fact, the professed goal is to produce a variety of lower bounds. In order to evaluate the performance of the developed algorithms, various small to large instances are generated and, then, the algorithm is applied to simulated instances. Computational results indicate that algorithms based on L-shaped and Lagrangian relaxation methods produce better lower bounds. Moreover, by strengthening the model, algorithms based on Lagrangian relaxation method are able to produce better lower bounds with respect to the algorithms based on the L-shaped method in a short time period.