Asphaltenes are blamed for several operational issues throughout the petroleum value chain such as: reducing volumetric production of wells, plugging of valves, pumps, tubing and pipelines during lifting, production, transportation, and storage. During refining operations, asphaltenes can cause heat exchanger and oven fouling and contributing to catalyst poisoning by coke and metal depositions. There are several techniques that can be used to deal with asphaltene precipitation issues: a) control pressure or other operational variables such as oil comingling, b) periodical cleaning (either chemical or mechanical), and c) additive injection to prevent asphaltene precipitation. Specifically, current methods for additive evaluation are time-consuming, rely exclusively on measurements at room temperature and could be very costly if they are carried out at reservoir conditions. Thus, the need for a method for rapid assessment of additives to prevent asphaltene precipitation is necessary to maintain well production and maximize economic benefits.

A new analytical technique was developed for screening and selection of asphaltene dispersants at reservoir conditions (<200°C). It is based on the On-Column Filtration method (Rogel 2009 and Ovalles 2015) and can quantitatively measure asphaltene dispersion activity by determining the percentage of reduction of asphaltene content versus the case without additives. It allows performing mass balances, is fast (<50min), repeatable, has small human intervention and uses a small amount of sample. A nonylphenolformaldehide resin (MW = 1600 g/mol) and three commercial additives were tested using gravimetrically separated asphaltenes and a Mid-continent crude oil. Reductions in the asphaltene contents up to 56% were found for the former and 38% for the latter. The mechanism in which asphaltene inhibitors and dispersants interact with asphaltenes depends on the type of additive and asphaltene composition and concentration. Some mechanistic considerations on the action of additives to prevent asphaltene precipitation are presented.

You can access this article if you purchase or spend a download.