Interação entre minerais expansíveis e fluidos glicerinados como causa da acreção.

Abstract

Problems related to the instability of oil wells such as agglomeration and accretion of cuttings lead to an increase in non-productive time in the operation of drilling, and careful selection of drilling fluid components can help to reduce the potential of this phenomenon, since the interactions between the formations and The fluid can be regulated to increase and improve wellbore stability. Of this In this way, the present work aims to carry out an analysis of the interaction between expandable minerals present in reactive formations and based drilling fluids of glycerin, in the conception and extension of the phenomenon of accretion in oil wells. Therefore, the accretion capacity of bentonite pellets was evaluated, which have a high content of expandable clay minerals, with the use of drilling fluids based on glycerin with different types of inhibitors in its composition. The study was carried out in three stages: in the first, the pellets were characterized by means of the x-ray diffraction (DXR) and Atterberg indices; in the second, the fluids of perforation were characterized through the rheological study; and in the third stage it was evaluated the interaction between the expandable minerals present in the pellets and the fluids drilling holes studied through accretion tests. The obtained results revealed that the pellets studied are predominantly composed of illite-smectite (I-S) interstratified clay minerals, and are classified as highly plastic, characteristics that show the nature of the sample to be reactive with a high degree of expansion. Furthermore, the percentages of accretion were significant for all fluids studied. Therefore, it was concluded that the use of glycerin in drilling fluids did not provide mineral stabilization capacity expandable elements present in reactive formations, even with the use of different types of expansion inhibitors, which were not satisfactory in reducing of the effects of rock expansion.