Decision-making processes for selecting an oil exploitation strategy can be complex due to the high number of variables to be optimized. Many times, it can be unfeasible to search an optimal solution by evaluating a high quantity of variables simultaneously. In this case, assisted methods that involve engineering analyses and mathematical optimization algorithms are an alternative to obtain a good solution. This paper shows the application of an assisted method to optimize a large number of variables of an oil exploitation strategy. The proposed methodology is to order and combine different optimization procedures with practical engineering analysis. The optimization variables include number and position of wells, platform capacities, wells opening schedule and wells shut-in time. The methodology is applied to a reservoir model based on a Brazilian offshore oil field to discuss the results obtained. Results indicate an efficient procedure for evaluating deterministic scenarios, suggesting optimization procedures for each decision variable and enabling the achievement of good quality solutions with a reasonable number of simulation runs. This is useful in many practical cases, mainly those, which require runs with long simulation time.

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Water injection performance depends on the petrophysical reservoir properties and fluid-flow characteristics. Reservoir simulation models should include rock properties variation and rock-fluid interactions and, when it is necessary, geomechanical phenomena. When water Injection above Fracture Propagation Pressure (IFPP) is used, its effects over the reservoir model performance, and specially, on waterflooding sweep efficiency, become a critical point to be assessed. Quantification of these effects using parameters such as the Recovery Factor (FR) and Net Present Value (NPV) is important for the water injection project dimensioning and to determine the feasibility and usefulness of the injection process to be implemented. Water injection under fracturing conditions is an important method to overcome the production decline caused by the injectivity loss in reservoirs with water injection. Also, the modeling of injectivity loss and fracturing processes are subject of several studies, which aim to understand these processes in order to enhance the results to be used for the reservoir development strategy proposal. The objective of this work is to quantify, using Sweep Efficiency and NPV as study parameters, the effects of anisotropies on the production performance during a waterflooding under fracturing conditions. The methodology proposed considers the simulation of scenarios in which the injectivity loss is represented by an analytical decline model, and the fracture is represented using a virtual horizontal well. This proposal is implemented in order to show the effect of the water injection - injectivity loss - fracturing process on the reservoir behavior. Three different fluid models were used to illustrate their effect in some production parameters and usefulness of fracturing process in several scenarios. The results show the applicability of water injection under fracturing conditions in different scenarios. In addition, this work shows the importance of the reservoir parameters into the injectivity loss and fracture propagation models, the significance of the FR and NPV in the quantification of these effects. Finally, the relation between the heterogeneity degree and production parameters is presented. Introduction Water injection is the most common method for oil recovery and pressure maintenance. Injectivity loss is the principal problem associated with water injection. Altoé et. al.1 describe that it is caused, mainly, when seawater, produced water or any other poor quality water is injected into reservoir. Solid and liquid dispersed particles from the injection water are deposited in the porous media; it can turn inefficient the injection process with time. Palson et. al.2 comments about different solutions that can be applied to improve the injection process:treatment of the water injection for removal suspended particles, bacteria and oil droplets,well workovers for removal the damage, using mechanical and chemical treatments. As mentioned by Souza et. al.3, any of these solutions can be expensive, some in CAPEX, others in OPEX. Actually, there is other option to attack the injectivity decline and it is know as water injection above the formation parting pressure. This option reestablishes the well injectivity creating high conductivity channels and avoids complex systems of water treatment. However, the apprehension to use water injection above formation parting pressure is associated to the canalization of the injected water towards producing wells leading to negative results for the production performance. Even though, this technique is applied in North Sea and Alaska (Ovens et. al.4, Ali et. al.5). Due to complexity and number of variables, involve in water injection above formation parting pressure, recent studies are focused in different aspects as fracture mechanisms, modeling and fracture's effects in the reservoir performance (Van den Hoek 6, Gadde et. al.7). To model those effects, the fracture behavior must be reproduced in the flow simulator and its effects in the behavior of the production during the process of injection of water. It also necessary study tools that allows model the injectivity loss. In this way, it can couple the process injection with injectivity loss and fracturing in a more complete and coherent way for refined and coarse simulation grids.