Aiming to increase hydrocarbon production, the oil industry has developed recovery methods whose purpose is to get more production. Thus, several problems may be encountered when making use of these techniques, mainly the conventional one. In addition, consideration of geological structures in reservoir engineering, such as fault zones, has fundamental character for determining realistic response for the production of hydrocarbons. In the case of faults zones, its consideration in the model has significant importance currently, especially with regard to the possibility of reactivation and possible loss of tightness of the reservoir. Thus, the aim of this study was assess reservoir models with a fault zone using partially coupled hydro-mechanical simulations. The methodology considers a fault zone whose behavior is given by the Mohr-Coulomb yield criterion. The plasticity model showed consistent results with the process of reactivation for the models. Thus, for the case where the objective is to determine the maximum flow rate of injection as well as its spatial configurations aimed at maintaining the field production, it is possible to establish the flow rate that may result in the initiation of the fault reactivation. Furthermore, the effect of surrounding rocks had a great influence in the time required to initiate the process of reactivation. As a general conclusion, it is stated that the consideration of fault zones in reservoirs, as well as surrounding rocks, must be taken into account to obtain more accurate response to the field behavior.

1 Introduction

The exploitation of petroleum began from the drilling of the first well of petroleum in the XIX century in the United States. From this point, aiming increase the petroleum recovery, the oil industry developed recovery methods whose objective is to obtain a higher production than that which would be obtained only as a result of the natural energy of the reservoir (Thomas 2001). In this context, several problems can be faced when one uses recovery techniques, mainly through the fluid injection, in geologically complex reservoirs.

Besides that, the consideration of geological structures in the reservoir engineering, for instance faults, has fundamental importance for determining realistic responses related to oil recovery factor, compaction of reservoir, seafloor subsidence, among others. In the specific case of faults, its consideration and analyses has been reported for several authors (Morris et al. 1996, Wiprup & Zoback 2000, Mildren et al. 2002, Streit & Hillis 2004, Chiaramonte et al. 2006, Færseth et al. 2007, Rutqvist et al. 2007, 2008, Soltanzadeh & Hawkes 2008, Zhang et al. 2009, Cappa & Rutqvist 2010, Ducellier et al. 2011, Jain et al. 2012, McDonald et al. 2012; Leclère & Fabbri 2012), due, mainly by its reactivation possibility. In the fault reactivation perspective during the field development, the objective is to prescribe the highest injection flow rate or the highest bottom hole pressure that can be applied in injector wells in order to maintain the reservoir pressure, without the failure of the faults. The process of fault reactivation, due the stress state variation, can result in an emergence of a preferential path for the hydrocarbon, implying in the most critical cases, in the leakage of fluid and possible loss of tightness of the reservoir.

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