(122h) Screening and Investigation on Inhibition of Sediment Formation in a Kuwait Light Crude Oil By Commercial Additives with Some Guidelines for Field Applications

Crude oil is a very complex mixture, consisting of myriad components, that during changes in operating conditions such as pressure, temperature and composition of the oil can trigger deposit formation during oil production operations. The deposit formation is a complex phenomenon that is mainly provoked by asphaltene aggregation and precipitation and/or by precipitation of wax or paraffin. The precipitation of asphaltene, and waxes occurs when crude oil characteristics change as a consequence of pressure, temperature variations, and/or chemical modifications, etc. The costs associated with cleaning of the deposition on the production equipment and the loss of profit opportunities can go beyond hundreds of millions US $. Thus, there is a strong incentive to search ways for mitigation of deposit formation during crude production process. The behavior of the extra heavy, heavy, medium, light and extra light crude oils when n-heptane is added to them has been studied experimentally. Asphaltene characterization, as a pre-screening for appropriate inhibitors, has been conducted using asphaltene phase diagrams (APD). For this purpose, two software were developed in both Matlab and Excel codes to predict stable and unstable regions for this crude oil sample. The (APD) generated from these software favorably are compared with phase behavior of other oil samples available in the literature.

The Kuwait Light crude shows continuous decrease in the sediment content with enhancing n-heptane content in the blend crude – nC₇H₁₆. Considering that the light crude oils have been reported to be more susceptible to cause asphaltenes deposition we decided to investigate the feasibility of inhibition of the sediment formation of the Kuwait Light crude oil by its treatment with commercial chemical inhibitors. The aim of this study is to verify the feasibility of suppressing the process of sediment formation in a light crude oil by treating this crude oil with commercial antifouling additives. Basic properties such as density and distillation (ASTM 7169), sulfur content, pour point, sediment, and SARA analysis were determined. The solvent power and the critical solvent power of the crude were determined as well. 14 types of different chemical inhibitors out of available 24 chemicals from 5 companies were screened for testing to inhibit the precipitation. Optimum concentration and the amount of reduction in precipitation were determined for all of these chemicals to identify the most suitable chemicals. Some recommendations are given for the for the field application of chemicals.