The plugging of tubings and pipelines by scale, asphaltene, and wax is a common problem in the oil production, transportation and refinery systems. Hot oiling, chemical wash and mechanical scraping have been used for many years to restore flow. There may be economic benefit to implement preventive treatments. We propose to consider the application of ultrasound as a potential preventive treatment. As a physical treatment, it is expected to be independent of the details of the chemical nature of the problem, i.e., it should be equally applicable to particles such as salt crystals, asphaltene precipitates, or wax. We will present experimental results showing the effects of application of ultrasound during precipitation and crystallization. Three systems were tested in this study; crystallization of salt from saturated aqueous solutions, re-dispersion of asphaltene in heptane, and pour point depression of diesel with different wax contents. The results show that, under the influence of ultrasound during the phase transition, there was a reduction of the size of the salt crystals, precipitated asphaltene was re-dispersed, and the temperature at the pour point of diesel with different wax contents was substantially lowered.
The plugging of production tubing by scale, asphaltene, and wax is a common problem in the oil field. It is expected that these solids are all soluble under reservoir conditions. During the production process, for some reservoir fluids a change in thermodynamic state can cause the solids to come out of solution. Examples would include salt crystals from the aqueous phase, or asphaltene and wax from the oleic phase. If a sufficient amount deposits along the production tubing then the flow would be reduced. In more severe cases the well could eventually become plugged. Financial losses can result from production reduction as well as the cost of the subsequent workover. Sometimes the near wellbore area of the reservoir can be damaged during workover, resulting in additional revenue loss [1].
Some of the workover methods used by the industry are hot oiling, chemical wash and mechanical scrapping. While in concept simple, field implementation of these methods can be quite difficult for some wells. When the cost to correct these problems becomes too high there is incentive to search for preventive treatments. Historically, trickling in chemicals used for workover appeared to be an obvious extension of a cure into prevention. In recent years, many new chemicals have become available commercially [2, 3]. However, the cost of these chemicals is high. There is a need to search for a more cost-effective preventive treatment method.
About twenty years ago tools based on magnetic treatment using rare earth magnets became available commercially. There have been anecdotal evidences but little scientific data to support the use of these tools. It was only recently that Chow et al. [4] made a serious attempt to understand this type tools.
The objective of this study is to consider another physical method to either inhibit the growth of the particles coming out of solution or to modify the bonding between them.
