Efficiency of Selected Terpene-Based and Conventional Solvents in the Dissolution of Asphaltene Deposits

Summary Hydrochloric and organic acids have been extensively used to enhance well productivity or injectivity in tight carbonate formations (10 to 50 md). The use of these acids, however, can cause instances of complete production loss. This is especially common due to incompatibilities of the acidizing fluid and oil, which can lead to the formation of acid/oil emulsions and sludge formation. Consequently, it is necessary to properly identify and remove such emulsions or precipitations without causing any further damage. Compatibility studies were conducted using representative crude samples and hydrochloric acid (HCl). The experiments were conducted at various temperatures up to 240°F using high-pressure/high-temperature (HP/HT) aging cells for both live and spent acid samples, in which some of the experiments included an antisludge, an iron-control agent, and a demulsifier. In addition, another set of experiments was performed in the presence of ferric ions (Fe3+). The total iron concentration in these experiments was varied between 0 and1,000 ppm. The results showed that commonly used acid systems were not compatible with representative oil field samples. The amount of sludge formed and the stability of formed emulsions increased significantly in the presence of ferric ions and was more severe in the presence of hydrogen sulfide (H2S). Using a field case, this paper will cover the methodology used to ascertain the source of formation damage from acidizing, study the different factors that influence the formation of acid/oil emulsion and sludge formation mechanism, and show how they can be removed. In this example, acid/oil emulsions, sludge formation, and improper drilling mud filter-cake removal were the reasons behind the production loss. However, the methodology can be expanded to cater the many acidizing failure cases faced in the industry worldwide.

show abstract

Alternative Environmentally Friendly Solvents for Asphaltenes/Paraffins Removal from Oil Producing Wells

Al-Taq

Alfakher

Alrustum

et al. 2019

Day 4 Thu, November 14, 2019

View full text Add to dashboard Cite

Aromatic-based solvents, including benzene, toluene, xylene (BTX) and their derivatives have been successfully applied for asphaltene removal from downhole and surface facilities. These solvents are considered non-environmentally friendly due to their associated health and safety concerns including high toxicity, low biodegradability and low flash point. Currently, more attention has been given in the oil industry to develop environmentally friendly asphaltene solvents. This paper examines several environmentally friendly solvents derived from natural precursors to dissolve asphaltene, wax and combined asphaltene/paraffin organic deposit. A group of plant-derived and terpene-based asphaltene solvents with flash points ranging from 50.5 to 136 °C was examined in this study. Extracted asphaltene from a crude oil and wax obtained from distillation were used to assess solvency power of these solvents. Solubility of organic deposits containing more 42 wt% asphaltene with associated paraffin was evaluated in these solvents. The performance of these solvents was examined as a function of soaking time and temperature. These environmentally friendly solvents showed comparable solvency power to toluene. The lowest flash point solvent exhibited the highest solvency power for asphaltene while the opposite relation was observed for the wax sample. The lowest flash point (50.5 °C) solvent was able to dissolve 91 wt% of the asphaltene sample after soaking for 2 hours at ambient temperature compared with the highest flash point solvent (136 °C), which dissolved only 7.4 wt% at the same conditions. For wax, the solvent with the second highest flash point (132 °C) was able to dissolve 97 wt% of the wax while the solvent with a flash point of 50.5 °C was able to dissolve 85.5 wt% at ambient temperature and after 2 hours. Some of the examined environmentally friendly solvents showed very high dissolution power to organic deposits composed of asphaltene and paraffin where a solubility of 96 wt% was obtained at 80 °C and after a soaking time of 6 hours. The paper will discuss these results in detail.

show abstract

Efficiency of Selected Terpene-Based and Conventional Solvents in the Dissolution of Asphaltene Deposits

Cited by 4 publications

References 3 publications

Flow Assurance Solids Chemical Analysis and Characterization

Flow Assurance Solids Chemical Analysis and Characterization

Matrix Acidizing: A Laboratory and Field Investigation of Sludge Formation and Removal of Oil-Based Drilling Mud Filter Cake

Alternative Environmentally Friendly Solvents for Asphaltenes/Paraffins Removal from Oil Producing Wells

Contact Info

Product

Resources

About