Planning of infill drilling in oil rim reservoirs is a challenging task. In the case of thin oil rims with large gas caps, early gas breakthrough and gas cycling can cause serious problems, especially in a co-mingled production environment and heterogeneous geological conditions. For the last years, high resolution geological models have been widely used to plan new wells trajectories. However, the dynamic behavior of the reservoirs was widely ignored. These effects are related for instance to interference phenomena which directly impact the optimum number of infill wells during the concept selection in a field development stage. High resolution geological models together with reservoir simulation models using parallel computing allow a more sophisticated workflow to optimize horizontal well placement.Interactive well planning was initially used to optimize the horizontal well location within the 3-D reservoir model, ensuring a smooth trajectory, near placement to the current oil-water contact, and steer away from the gas cap to delay gas breakthrough. The wells were then translated into the dynamic simulation model where a detailed modeling of both reservoir inflow and well bore hydraulics were used to optimize the flow at well completion level. An iterative process was used to maximize the well production by balancing the pressure drop along the horizontal section in order to maximize oil production and minimize gas-oil-ratios at well and field level. As a result the number of drainage points needed to effectively recover the existing oil was reduced from 20 to 4, realizing 75% of the total infill potential. This paper describes the workflow for optimization of horizontal well performance during the field development planning stage of an offshore oil rim brownfield. The field is highly constrained with gas production, which constitutes about 90% of the total field production. Crestal gas re-injection is ongoing as a pressure maintenance effort. Most wells are completed in commingle horizontal wells. Successful infill wells must be placed and completed appropriately to reduce gas and therefore maximize oil production. Among the parameters studied for the field development plan are: type of well, well completion options, offset from fluid contacts and well orientation. This paper also describes wellbore dynamic behavior that has not been extensively covered in the literatures. It illustrates the challenges of placing and optimizing production along the horizontal section of the wells and how an efficient control of completion and depletion levels is used to optimize and accelerate oil production in an aging oil rim field. Extensive reservoir simulation on a full field model was utilized for the initial well placement study. In parallel, geosteering feasibility assessment was conducted and tied to the reservoir simulation results. These were the basis for the subsurface team to determine the most suitable wellbore trajectories and conformance requirements. At the same time, a comprehensive sand production predicti...

Reservoir management is a standard industry practice to maximize oil recovery; however, in mature fields the full potential is often not realized. Unlike greenfield developments, mature oil fields deal with existing infrastructure and fluid export schemes with capacities designed for peak production sometimes decades ago and/or different production techniques.Substantial increases in producing gas-oil ratios and water production can occur over the lifetime of the field. Falling reservoir pressures cause not only a drop in manifold pressures and the need for artificial lifting technologies, but potentially may also lead to the necessity of flaring associated gas if no appropriate compression facilities are available. Metering and surveillance facilities as well as reservoir management infrastructure are often basic and represent the technology available at the time of the platform installation.The current paper discusses optimization techniques, using dynamic simulation with a coupled surface to reservoir model, to show how flaring affects gas injection on field scale. The extensive study was conducted for a thin oil rim Brownfield at the upper limit of the current handling facilities. Two gas injectors in the gas cap aid the reservoir energy by re-injecting a portion of the produced gas.The study showed that flaring over longer periods of time potentially caused a rapid decline in reservoir energy and thus shortens the life of the field. This in turn causes the deferral of a substantial amount of oil production. Further analysis was conducted investigating ways to extend the life of field. A solution is proposed to enhance the ageing infrastructure and modifying the current reservoir management practices at low cost. It was shown that the elimination of flaring does not only help in protecting the environment but is also attractive when there is an increase in energy demand.

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