Evaluation of the settling behavior of hematite in an olefin-based drilling fluid using gamma-ray attenuation technique

Abstract

As oil is the main component of the world's energy matrix, it has a strong influence on the dynamics of countries' economic and monetary systems. The drilling of an oil well is performed using specific drilling fluids, so that this process is as fast and safe as possible. Each region of the well requires a drilling fluid with particular characteristics. The rheological behavior of fluids affects both the cleaning process of wells, via transportation of cuttings to the surface, and the sedimentation of cuttings and particles present in the fluid formulation during drilling fluid flow interruptions due to corrective or preventive operating stops. Thus, this study aimed (i) to evaluate the rheological behavior of the additive hematite in olefin-based drilling fluids, (ii) to indirectly monitor the volumetric concentration variation of hematite particles during sedimentation using a non-destructive method called gamma-ray attenuation technique, and (iii) to determine constitutive equations for pressure on solids. The results showed that the addition of hematite in the olefin-based drilling fluid resulted in a non-Newtonian behavior, indicated by the behavior index of the power-law rheological model below 1. This behavior was accentuated by the increase in the proportion of hematite from 7.27 to 9.28%. Regarding the variation of volumetric concentration of solids in sedimentation, the increase in solids concentration retarded the settling process. In addition, the sediment formed presented a compressible behavior; therefore, the constitutive equations for pressure on solids presented a power index.