Effect of Aging on the Removal of Asphaltene Deposits with Aromatic Solvent

In-situ catalysis of green lubricants into graphitic carbon by iron single atoms to reduce friction and wear

Reducing friction and wear in moving mechanical systems is essential for their intended functionality. This is currently accomplished by using a large variety of anti-friction and anti-wear additives, that usually contain sulfur and phosphorous both of which cause harmful emission. Here, we introduce a series of diesters, typically dioctyl malate (DOM), as green and effective anti-friction and anti-wear additives which reduce wear by factors of 5-7 and friction by over 50% compared to base oil when tested under high pressures. Surface studies show that these impressive properties are primarily due to the formation of a 30 nm graphitic tribofilm that protects rubbing surfaces against wear and hence provides low shear stress at nanoscale. This graphitic tribofilm is prone to form from diesters derived from short-chain carboxylic acid due to their lone pair effect, which stabilizes the carbon free radicals. Furthermore, the formation of this tribofilm is catalyzed by nascent iron single atoms, which are in-situ generated due to the mechanochemical effects during sliding contact. Computational simulations provided additional insights into the steps involved in the catalytic decomposition of DOM by iron and the formation of a graphitic carbon tribofilm. Due to its anti-friction and wear properties, DOM holds promise to replace conventional additives, and thus provides a green and more effective alternative for next-generation lubricant formulations.

Comparative Static and Dynamic Analyses of Solvents for Removal of Asphaltene and Wax Deposits above- and below-Surface at an Iranian Carbonate Oil Field

During production from oil wells, the deposition of asphaltene and wax at surface facilities and porous media is one of the major operational challenges. The crude oil production rate is significantly reduced due to asphaltene deposition inside the reservoir. In addition, the deposition of these solids inside the surface facilities is costly to oil companies. In this study, the efficiency of different solvents in dissolving asphaltene and wax was investigated through static and dynamic tests. The analysis of solid deposits from the surface choke of one of the Iranian carbonate oil fields showed that they consisted of 41.3 wt % asphaltene, and the balance was predominantly wax. In addition, the asphaltenes obtained from the surface choke solid deposits had a more complex structure than that of asphaltenes extracted from the crude oil itself. The static tests showed that xylene, toluene, gasoline, kerosene, and gas condensate had the highest efficiencies in dissolving solid deposits; conversely, diesel had a negative impact on dissolving solid deposits. Static tests on pure asphaltene showed that, among the tested solvents, gas condensate and diesel had a negative effect on the solubility of asphaltene. The dynamic core flooding results showed that asphaltene deposition inside the cores reduced the permeability by 79-91%. Among the tested solvents, xylene, gasoline, and kerosene resulted in the highest efficacy in restoring the damaged permeability, and higher efficiency was obtained with an equivalent solvent injection rate of 1 bbl/min versus 3 bbl/min.

Improving the Efficiency of Oil and Gas Wells Complicated by the Formation of Asphalt–Resin–Paraffin Deposits

A number of difficulties may be encountered in the final stages of oil field exploitation, including the formation of asphalt–resin–paraffin deposits (ARPDs). It is expedient to use complex technologies to remove the already formed deposits and prevent the formation of ARPDs. This paper focuses on the complex technology of oil field exploitation. This technology combines both the removal of organic deposits and the prevention of the formation of these deposits in the well bottomhole formation zone (BHFZ) system. The calculations for determining the process parameters of selling the ARPD inhibitor solution into the BHFZ are presented in this article. This complex technology includes the process of ARPD removal by flushing the well and the subsequent injection of the developed ARPD solvent into the BHFZ. In addition, the technology is complemented by a method of preventing the formation of these deposits. This method consists of squeezing the ARPD inhibitor and then pumping it by the selling fluid from five to ten times of the volume. This article contains a detailed calculation of the methodology and provides the diagrams for the solvent and inhibitor injection.

Toward molecular characterization of asphaltene from different origins under different conditions by means of FT-IR spectroscopy

Asphaltene is one of the polar and heavy fractions of crude oil that is complex from a molecular perspective. For this reason, the interaction between asphaltene molecules and the surface, as well as the interaction of asphaltene with chemicals such as amphiphile, are not well identified. Fourier-transform infrared spectroscopy (FTIR) is a useful tool for identifying the functional groups of molecules, as well as intra-molecular and inter-molecular bonds. Through reviewing previous studies, here the peaks in an FTIR spectrum of an asphaltene molecule were divided into polar, aromatic and aliphatic groups and discussed using quantitative indices. Then, the difference in the FTIR spectrum of asphaltene with wax and resin was addressed according to molecular structure. The effect of common impurities such as moisture, CO₂ and saturated and aromatic compounds of crude oil in asphaltene on the FTIR spectrum is assessed. Moreover, the application of the FTIR spectrum of asphaltene is used to determine the API value of crude oil, the asphaltene onset is given. In addition, possible changes in the FTIR spectra of asphaltene are investigated by various processes such as pyrolysis, microwave and ultrasonic radiation. Also, asphaltene subfractions is also one of the best methods to better understand asphaltene components. This study examines the FTIR spectrum of asphaltene subfractions from conventional methods and examines the spectral properties, which in many cases can be useful to researchers working in this field.