Contribuição à modelagem do repasse em poços verticais em rochas salinas

Abstract

The constant increase in world energy demand is the reason for the search for new sources of hydrocarbons. Especially in Brazil, the accelerated expansion of oil and gas exploration in ultra-deep waters in the marginal basins of Pre-Salt region stands out. This type of exploration presents several operational challenges to be overcome, among which is the existence of salt layers along the wells trajectory. The presence of evaporite rocks increases the complexity of drilling operations, as their creep mechanism (continuous deformation under a constant stress state) leads to deformations in the direction of the well closure. Depending on the intensity of the deformation, there may be imprisonment of the drill string and problems while running casing. Therefore, backreaming operations may be required to recondition the diameter of the well to its original state. Thus, the computational simulation of the problem is important to assist in decision making during drilling and in the technical and economic evaluation of well projects. The present work approaches the computational simulation of the backreaming through the Finite Element Method, seeking to contribute to an effective modeling of the problem by considering an element removal methodology and located remeshing due to the backreaming operation. To validate the proposed strategy, results are presented in order to allow the comparison with already verified approaches. The proposed methodology made it possible to eliminate the error previously caused by deactivating elements to represent the backreaming operation, improving the precision and realism of the simulations.