No abstract

When drilling an oil well, a viscous fluid is injected to aid drilling. This fluid is also responsible for removing the cuttings and maintaining structural stability of well. The rheology of this drilling fluid has a direct influence on the cleaning of the well, on the dynamics of the fluid in pipe and annular areas. Linear mathematical extrapolations for high pressure and high temperature environments can lead to rheology errors up to 75%. In this study, a finite volume model was developed to simulate the flow of a waterbased mud in annular and jetting environments in the drilling environment. Annulars were made by steel pipes and permeable formations. The fluids evaluated were developed empirically with xanthan gum and bentonite clay. The numerical results are consistent with literature and represent characteristics of a Yield Power Law fluid and a Bingham plastic. A comparison was made with water, allowing a correlation between rheological effects and fluid dynamics in annular and high vorticity regions.

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The aim of the present study is to analyze the effects of aligned magnetic field and radiation on biomagnetic fluid flow and heat transfer over an unsteady stretching sheet with various slip conditions. The magnetic field is assumed to be sufficiently strong enough to saturate the ferrofluid, and the variation of magnetization is approximated by a linear function of temperature difference. The governing boundary layer equations with boundary conditions are simplified by suitable transformations. Numerical solution is obtained by using the bvp4c function technique in MATLAB software. The numerical results are derived for the velocity, temperature, the skin friction coefficient, and the rate of heat transfer. The evaluated results are compared with analytical study documented in scientific literature. The present investigation illustrates that the fluid velocity is decreased with the increasing values of radiation parameter, magnetic parameter, and ferromagnetic interaction parameter, though is increased as the Prandtl number, Grashof number, permeable parameter and thermal slip parameter are increased. In this investigation, the suction/injection parameter had a good impact on the skin friction coefficient and the rate of heat transfer.

With the exploration of marine oil fields in deep and ultra-deepwater regions, the need for studying different methods of well construction has increased. Nowadays, the technique of laying conductive casing by jetting is the most widely used for the starting phase of a well in such conditions. In this scenario, in early layers, where the marine soil is in contact with seawater, this material can present itself as a fine mud, characterizing a cohesive non-drained soil, with low shear strength, being considered a material with viscoplastic behavior. Thus, as such, using fluid rheology to analyze it may represent a valid option; being possible to classify it as a Herschel-Bulkley fluid. The use of computational modeling and numerical simulation represent an alternative to understand the behavior of soil during jetting. In this context, this work focuses on developing a computational modeling of the jetting of marine soil, based on the soil fluid dynamics approach, using computational fluid dynamics (CFD - Computational Fluid Dynamics) software SIMULIA XFLOW, version 2020. This work aims to investigate the deformation in the seabed in response to an incident vertical jet using different drilling fluids, also modeled as viscoplastic materials. Drilling fluids suitable for jetting and a fluid with a higher specific mass were considered. For the proposed modeling of the soil and drilling fluids considered, the main parameters used were the yield point, consistency index, behavior index, and the boundary viscosity. The latter was necessary to implement the modified Herschel-Bulkley model used by the software. Results show that the excavated cavity presented a similar behavior for the drilling fluids suitable for jetting, indicating that the rheology of the drilling fluid does not interfere with the deformation of the soil. However, a significant influence on the profile of the excavated cavity was observed when implementing the drilling fluid of higher specific mass in the jetting, which deformed the soil at greater depths.