This paper presents a method for optimizing the itinerary of workover rigs, searching for the route of minimum total cost. The total cost of a route includes the rig expenses (transport, assembly and operation), which are functions of time and distances, plus the losses of revenue in wells waiting for the rig, which are also dependent of time. A reservoir simulator is used to evaluate the monetary influence of the well shutdown on the present value of the production curve. Finally, search algorithms are employed to determine the route of minimal cost. The Simulated Annealing algorithm was also successful in optimizing the distribution of a list of wells among different workover rigs. The rational approach presented here is recommended for management teams as a standard procedure to define the priority of wells scheduled for workover. mostly on opinion and superficial calculations.
A rational procedure is needed, based on a consistent method. Ideally, it should be a This paper presents a study of the procedure that integrates the existing methodology for optimizing the itinerary of knowledge of the reservoir behavior with the workover rigs. The task at hand is the search logistical programming of the production for the route of minimum total cost for a given operations. list of wells waiting for the workover rig. The At the same time, the frequent shutdown total cost includes the rig expenses (transport, of a large number of wells for several days assembly and operation), which are functions may have a significant impact on the revenue of time and distances, plus the losses of of an oil field, thus justifying the concern to revenue in the wells waiting for the rig, which minimize the cost of workover. are dependent of time. Therefore, the total cost With all the aforementioned in mind, a depends on the ordering of the wells in the rational approach is recommended as a itinerary. standard procedure to define the priority of the In order to compute the wells' losses, it is wells scheduled for workover. The proposed necessary to evaluate the monetary influence methodology is based on hard data of the wells of each well shutdown on the present value of and reservoirs, and on a clearly defined criteria the production curve. In the present work, this minimum cost. analysis is made through the use of a reservoir simulator. The results are presented in the form of revenue loss factors. Failure to account 1. LITERATURE REVIEW correctly for the revenue losses would mislead The following review is divided in two the itinerary programmer to select less than parts quantification of losses and search for optimum routes. the best path, which are directly related to the Four algorithms to determine the optimum main issues of the present study. route are described follow the next closest
