Petroleum, which is one of the most complex mixtures existing in nature, is equilibrated and coexists with the aqueous phase at reservoir conditions. However, depending on the oil viscosity, strong emulsions may be formed due to the high shear imposed by the production process. As a consequence higher temperatures conditions are necessary for the oil separation treatment. Therefore it is important to assure that scale inhibitors are thermally stable and able to act in what are considered extreme temperatures such as the ones used in heat exchangers, for example 16 °C. This work aimed to evaluate the influence of temperature in the scale inhibition activity for different active materials of chemical inhibitors, such as: Nitrilotris (methylene) tri phosphonic acid (NTP), Diethylenetriamine penta (methylphosphonic acid) (DETPMP), and polyvinyl sulphonate (PVS). Aqueous inhibitor solutions were aged in the temperature conditions between 60 to 160 °C for different times (6, 12 and 24 hours). Raman spectroscopy, NMR (31P, 1H and 13C) and FT-MS techniques were used to characterize chemical species from aged and original inhibitor solutions. Different from previous works, these techniques allow identification of some degradations products. Additionally, dynamic performance tests were conducted to evaluate scale inhibitor performance of the solutions. Results of the chemical characterization of the original and thermally aged PVS showed no compositional differences. Dynamic testing for barium sulphate scale showed that minimum effective concentrations remained constant in all assays. However, for the NTP and DETPMP products, at the highest temperature (160 °C, after 24 hours of testing) some degradation products were identified, such as methyl phosphonic acid, and especially, amino methyl phosphonic acid. As a consequence of the structural breakdown of the phosphonate molecules, confirmed by chemical analysis using FT-MS and NMR, the efficiency of inhibition of barium sulphate scale was reduced. The paper presents a methodology to evaluate and understand the behavior of different chemical inhibitors for extreme temperature conditions and highlights the demand for new stable molecules for high temperatures.
Scale occurrence can cause oil and gas production loss with high economic impacts. Currently, the use of chemicals is one of the key strategies for scale management. A laboratory tests protocol is essential to qualify and guarantee chemical effectiveness in the field. The objective of this work is to present a protocol that includes improvements in the procedures to evaluate scale inhibitors and allows wide application to several production scenarios. The protocol is an improvement based on published international technical standards and the literature. These adjustments of the experimental procedures enabled the representation of a wide range of scaling scenarios from reservoir to topside facilities. An efficient application of scale inhibitor includes the definition of the ionic composition of aqueous fluids as well as the pressure and temperature conditions of the target scenario. To perform the laboratory tests, synthetic waters are prepared to represent the water production scenario, including pH. The tests are performed using synthetic produced water, including evaluation of fluids compatibility (one or two phase experiment), thermal stability and static and dynamic performance (DSL-dynamic scale loop). The proposed test protocol allows the qualification of scale inhibitors to the production scenario considered, reducing the associated uncertainties of upscaling from laboratory to field. The availability of the company's protocols makes it possible to achieve greater accuracy in the recommendation of commercial scale inhibitors, allowing a better cost-benefit with the optimization of the effective minimum concentrations. In addition, this availability encourages the development of new generation inhibitors for challenging scenarios with high scaling potential. The improved protocol is designed to represent critical salt precipitation scenarios, similar to those found in the Brazilian Pre-salt (high salinity, high temperature, high saturation ratio, high CO2 content), and has been successfully applied in the screening and qualification of scale inhibitors.
Um mecanismo alternativo para a indução assimétrica 1,4, na adição estereosseletiva da (R)-pantolactona ao 2-fenilpropilceteno foi investigado teoricamente. Um mecanismo envolvendo uma transferência de hidrogênio intermolecular foi proposto, que considera a participação ativa da dimetiletilamina e seu íon como agentes de transferência de hidrogênio. No primeiro passo, uma molécula de dimetiletilamina neutra interage com o anel de 7 membros do enol intermediário. Uma interação ácido-base específica é estabelecida entre o grupo hidroxila do enol e o átomo de nitrogênio da amina. A amina neutra é básica o suficiente para remover o hidrogênio. Uma outra molécula de amina protonada doa seu hidrogênio à ligação dupla C=C, para fornecer os produtos desejados. A estereoquímica foi definida pelo modo como as moléculas de amina neutra e protonada aproximam-se do enol. O excesso diasteroisomérico encontrado concorda com o dado experimental [para (S, R) e (R, R) é de 99:1].An alternative mechanism for the 1,4-assymmetric induction in the stereoselective addition of (R)-pantolactone to 2-phenylpropylketene was theoretically investigated. A mechanism involving an intermolecular proton transfer assisted by two amine molecules was proposed, which considered the active participation of the dimethylethylamine and its ion as proton transfer agents. In the first step, a neutral dimethylethylamine interacts with the seven-membered ring of the enol intermediate. A specific acid-base interaction is established between the hydroxyl group of the enol and the nitrogen atom of the dimethylethylamine. The neutral dimethylethylamine is basic enough to remove the proton. Another protonated dimethylethylamine is considered to donate its proton to the C=C double bond to give the desired products. The stereochemical outcome was defined by the way that the neutral and protonated dimethylethylamine approached to the enol. The diastereoisomeric ratio found is in good agreement with experiments [for (S, R) and (R, R) it is 99:1].
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.