Investigation of wax deposition prevention by using n-heptane for sustainable energy production from Fang oilfield

Abstract

Waxy crude oils are normally found in petroleum reservoirs. Crude oil from wax formation is one of the crucial problems for flow assurance of pipeline transportation in oil and gas production. This issue can commonly cause wax deposition problem and it has made huge amount of economic loses such as production, time and maintenance cost. Therefore, it is a critical aspect to deal with wax deposition for crude oil flow assurance, especially in cold climate surface region. Nowadays, there are many methods that have been applied to reduce the wax deposition. In general, three methods are commonly utilized, mechanical, thermal and chemical ones. Among them, the usage of chemicals is commonly used in field because they can be applied easily rather than other techniques. In this study, n-heptane is select to study the prevention the wax deposition because its property can reduce the pour point and wax deposit of crude oil. It is easily available as well. Therefore, the aim of this research is investigate the effects of temperature and different chemical concentration on pour point and wax deposition of crude oil at three different temperature ranging from 35 to 55 °C by applying cold finger method. Also, the pour point of crude oil is measured with different n-heptane concentrations by ASTM method. Moreover, the effect of different chemical concentrations on wax appearance temperature (WAT) is examined the temperature between from 80 °C to 40 °C with three different shear rates by viscometry method. From the results, it is reported that the total wax deposits from the cold finger depend on the amount of chemical concentration used. WAT with 20% n-heptane provides the highest performance for WAT reduction with 41 °C. Compared to 5%, 10% and 15% n-heptane concentration, WATs are reduced to 45 °C, 44 °C and 43 °C, respectively. For the pour point results, the higher amount of n-heptane concentration offers the higher reduction in pour point temperature and pour points are reduced significantly from original pour point at 36 °C to 34 °C, 30 °C, 26 °C and 22 °C with 5%, 10%, 15% and 20% n-heptane, respectively. It is also found that the amount of total wax deposits decrease when chemical concentrations increase. Moreover, the decline of temperature is found as one of the main factors to cause more wax deposition. There is a highest wax deposit reduction rate with 20% n-heptane at different temperatures compared to other concentration. The wax deposition is reduced over 50% for each concentration. Therefore, this result is useful for the application of wax deposition, pour point and WAT studies in the crude oil production with less damaging environment for sustainable energy production.