Avaliação experimental do efeito da rotação na força de retirada da coluna de perfuração de um poço horizontal

Abstract

With the growing interest in cost reduction in oil extraction, it is necessary to understand the physical phenomena involved in the extraction processes. In this paper, the influence of rotation in a tripping operation of a drill string in a horizontal well in the presence of cuttings bed is studied. Although there are several studies on the influence of rotation on cuttings bed, there is only one study that considered the translation of the drillstring, but without the rotation. Aiming to fill this gap, the presente study was carried out using the Torque and Drag Experimental Unit at the Research Center for Rheology and Non-Newtonian Fluids (CERNN) of the Federal University of Technology of Paraná (UTFPR). Maneuvers were simulated in which a drillstring is pulled through a pipe representative of a horizontal well filled with water. As parameters, the translation speed was 30cm/s, with rotations of 50rpm, 100rpm and 150 rpm and bed ratios of 0.22, 0.33 and 0.47. The pull-out force was measured during each test run through a load cell and the behavior in each condition was analyzed and compared with what was predicted in the literature. It was observed that rotation accelerates the formation of an obstruction in all bed ratios. At lower height, the mean force decreased when the obstruction reached steady state size. At the two largest heights, rotation accelerated the clogging of the well, a condition in which the obstruction grows indeterminately. It was also observed that the interaction of the drill bit with the cuttings bed had a greater influence than the friction of the drill string with the bed.