Tubular flow restrictions caused by solids deposition create serious oilfield problems. Solids normally originate from either asphaltic or paraffinic oil. Hydrates add another dimension to the problem when water production begins. Most solutions center on the use of aromatic solvents for asphaltenes and chemicals or heating for paraffins.
In this study, we seek preventive measures to minimize solids deposition by altering characteristics of fluid flow in the wellbore. The knowledge of fluid thermodynamic behavior, and the application of fluid principles and heat flows, constitute the essence of our approach. Specifically, we present a steady-state model that allows computation of wellbore pressure and temperature profiles for a hot-circulating fluid in the case of parrafins. The same model is used to study the p-T behavior of asphaltic oil while circulating a cold fluid.
A fluid-temperature model is also presented when intermittent or continuous injection of solvent is sought through a chemical-injection line. Both models are general in that flows in offshore wells can be handled rigorously.
Computational results show that preserving energy of paraffinic oil is feasible by circulating hot fluid in the annulus and/or using insulation, thereby keeping solids in solution. The use of an unsteady-state flow model sheds light on the time available for well intervention before the onset of deposition. Similarly, cooling of fluids may help produce asphaltic oils under favorable conditions.