Crude Charecterization and Modelling of Wax Deposition for Flow Assurance

Abstract

Flow assurance basically involves ensuring the fluid flow as intended in a pipe or a well. Wax deposits begin to form when the temperature in the crude flow line falls below wax appearance temperature (WAT). This condition leads to reduced production rates and larger pressure drops. Wax problems in production wells are very costly due to production down time for removal of wax. Therefore, it is necessary to develop a solution to wax deposition. In order to develop a solution to wax deposition, it is essential to characterize the crude oil and study phase behavior properties. Flow assurance relies on well-established sciences like fluid mechanics, thermodynamics, mechanical engineering, chemical engineering, chemistry, discrete mathematics, automation, and computer science. n-Paraffin‟s are predominantly responsible for this problem. To improve the efficiency of the transportation and the crude oil quality, prevent blockage, preventing and removing wax is very important. This study summarizes the results of the various experiments of viscosity versus time at constant shear rate. The subtasks completed during this study includes experiments to understand the effect of pre-treatment on crude behavior, comparison of viscosity of crudes from different well as a function of time at different shear rate. The viscosity variations of crude having different wax percent are also analyzed as a function of time. Wax deposition is one of the most important factors for flow assurance, and hence needs to be modeled. There are various models present in the literature. Matzain model and Rygg, Rydahl and Ronningsen (RRR) are studied. The RRR (Rygg, Rydahl and Ronningsen) model is a multi-phase flow wax deposition model which predicts wax deposition in wells and pipelines. This model estimates the wax deposited along the pipeline due to temperature gradient and shear dispersion effect. The Matzain model incorporates shear stripping