Experimental study of asphaltene onset condition and deposition using electrical deposition technique in the presence of various additives: A novel strategy

Abstract

Asphaltenes (ASPs) are regarded as high molecular weight components that often deposit in the production lines and downstream infrastructure, leading to pressure drop and reduced production rate. In this paper, we investigated the potential of electro-deposition of ASP an Iranian crude oil sample encountering ASP deposition problems, to reduce the risk of well shut-in. In this regard, a systematic research plan has been designed to use the electro-deposition technique to precipitate and deposit ASP different fluid samples incluiding crude oil/n-heptane, synthetic oil (containing the same ASP)/n-heptane, crude oil/n-heptane/additive and synthetic oil/n-heptane/additive are utilized. The additives such as Linear Alkyl Benzene Sulfonate (LABS) as a surfactant, metal oxide nano-particles such as SiO2, γ-Al2O3, and TiO2 and synthesized mixed-metal oxide nano-particles compounds such as CeNiO3, CeZrO4 and CeCaO3 were used. This work reveals the effect of these additives on the deposition rate of ASP particles from crude oil and compares their effectiveness. Using a homemade apparatus, the optimum direct-current electric field (EF) and time for ASP deposition were found, followed by finding the best solution of crude oil and n-heptane. As for the additives, LABS showed that ASP deposition is critically decreased on the cathode at 2000 ppm for crude oil and 1500 ppm for synthetic oil. Nano-particles exhibit different behavior in an EF. The experimental results indicated that by increasing the concentration of nano-particles, the amount of ASP deposit on the anode decreases. The results indicated that synthesized mixed-metal oxide nano-particles do not change the charge type of ASP and result in ASP deposition reduction utilizing a very low number of nano-particles. Currently, electro-deposition is a key solution to remove ASPs from crude oil. This is due to its high energy efficiency and relatively simple process. Comparing the effects of these newly proposed additives showed that, CeZrO4 nano-particles are more efficient to inhibit ASP deposition.