SEPARATION OF SUSTAINABLE EMULSIONS IN THE INSTALLATION OF PREPARATION OF OIL WITH USING DEMULGUATORS OF DIFFERENT NATURE AND MICROWAVE RADIATION

ABSTRACT

In this article, the separation of stable emulsions in an oil treatment unit using demulsifies of various nature and microwave radiation is studied. It has been established that in the thermochemical method of oil demulsification with the combined use of microwave radiation, the nature, composition and properties of the emulsions to be separated should be taken into account. At the same time, a stepwise analysis of the process of oil demulsification by thermochemical and microwave methods makes it possible to scientifically substantiate the rational conditions and stages of their application. In the process of demulsifying oil with a high-strength armor shell of water globules, it is recommended to jointly use a composition of demulsifiers consisting of ionogenic and nonionic surfactants and microwave radiation of individual stages of this process.

АННОТАЦИЯ

В данной статье приводятся результаты разделения устойчивых эмульсий в установке подготовки нефти с использованием деэмульгаторов различной природы и микроволнового излучения. Установлено, что при термохимическом способе деэмульгирования нефти с совместным использованием микроволнового излучения следует учитывать природу, состав и свойства разделяемых эмульсии. При этом по стадийный анализ процесса деэмульгирования нефти термохимическом и микроволновым способами позволяет научно-обоснованно определить рациональные условия и стадии их применения. В процессе деэмульгирования нефти с высокопрочной бронирующей оболочкой глобул воды рекомендуется совместно использовать композицию деэмульгаторов, состоящих из ионогенного и неионогенного ПАВ и микроволновое излучение отдельных стадий данного процесса.

Keywords: oil, water-oil emulsions, oil-water emulsions, thermochemical process, microwave radiation, ionic, nonionic, surfactant, demulsifier, demulsification.

Ключевые слова: нефть, водонефтяная и нефтеводяная эмульсии, термохимический процесс, микроволновое излучения, ионогенность и неионогенность, поверхностно-активные вещества, деэмульгатор, деэмульсация.

Introduction. Oil production in many countries of the world is complicated by the formation of stable water-oil emulsions (WOE), the destruction of which requires the use of highly active emulsifiers or their compositions, external mechanical, electropgysical and other types of impact [1-2].

In Uzbekistan, such stable WOEs are mainly formed in the fields of Jarkurganneft JSC dur to the high content of the produced oils, resins, asphaltenes, paraffins, mineral salts, etc.

For example, the use of imported highly active emulsifiers, even in excessive quantities, does not always allow reaching the values of oils in terms of the residual content of water and salts, which negatively affects the processes of their processing, corrosion of metal equipment, pipelines, etc. [3-4].

Therefore, an urgent task for scientists today is the development of effective methods for emulsifying such heavy oils of complex composition using unconventional methods of external electrophysical exposure.

Currently, one of the most perspective methods for intensifying chemical and technological processes, including destruction and separation of stable WOEs is considered their microwave radiation, which, in contrast to traditional convective heating, allows several tens of times faster heating and changing the physicochemical properties of such emulsions [5].

Consequently, the combined use of thermo chemical and microwave methods of destruction and separation of stable WOEs can significantly save the consumption of expensive imported demulsifierand other material and energy resources.

Therefore, the aim of the research was to establish the effect of thermochemical and microwave destruction methods and various demulsifiers on the separation of stable water-oil emulsions.

Research methods and obtained results. For the practical application of microwave radiation, it is necessary to determine the optimal stages of external influence in an oil treatment unit (OTU), taking into account changes in the composition and properties of emulsions. Therewith, the analysis is based on the technologic flowchart of the OTP, which in block form can be represented as following:

А)                                                B)                                                    C)             

Figure 1. Flowchart of the technology of oil preparation for industrial processing: A- block for dehydration and desalting of stable WOE; B- block for dehydration and desalting of oil-water emulsion; C- block for the removal of reservoir ter and salts from commercial oil

In this technology, each block (A, B and C) has it's own composition, which determines its property, a suitable demulsifier (surfactant) and technological conditions for dehydration and desalting of oil

Therefore, a systematic analysis of this technological scheme is necessary for effective microwave radiation of individual stages of the process of dehydration and desalination of stable emulsions, as well as its intensification [6,7,8].

Table 1 shows the stages, i.e. levels of research of individual stages of the process of separation of stable WOE.

Table 1.

Systematic analysis of the stages of the separation of stable WOE using microwave radiation

It is obvious from Table 1 that each stage of the separation process of stable WOE performs separate physicochemical tasks, which ultimately ensure the achievement of the global goal, i.e. maximum removal of water and salts from commercial oil. At the same time, the quality of achieving local goals by stages shows the ways of their improvement and intensification. For example, the combined use of thermochemical and microwave separation of stable WOE increases the intensity of particular stages from Table 1of the process under consideration.

It should be taken into account that in the course of removing water from oil, the nature of the emulsion changes dramatically, i.ewater-oil emulsion (WOE), after removing a part of the formation water, is converted into oil-water emulsion (OWE), which in its physicochemical properties is very different from the first.

Therefore, the types and conditions of the demulsifier used or their compositions differ, as well as the modes and stages of microwave radiation in the technological scheme of the primary oil treatment in the fields.

The analysis of the operation of the OTU at «Jarkurganneft» JSC showed that in the first block (A), 50-60% of the reservoir water is removed from the stable WOE using a nonionic surfactant, and in the second - 36-39.5%. It should be noted that a stable WOE is formed in the second block.

Table 2 describes the conditions and main indicators of the separation of stable emulsions of various natures obtained from JSC «Jarkurganneft».

Table 2.

Indicators of separation of stable emulsions in blocks A and B

It is obvious from Table 2 that a change in the nature of the emulsion (WOE to OWE) strongly affects the duration of reservoir water separation from them as well as the amount of removed salts. Even an increase in the temperature of the emulsion to be derived from 40 to 60° C does not contribute to a significant reduction in the time of water separation. Replacing a part of a nonionic demulsifier with an ionic one partially helps to reduce the duration of reservoir water separation.

This can be explained by the fact that initially the dispersed medium (block A) in the emulsion is salt-dissolved reservoir water, which is a good electrical conductor, and in block B this function is performed by oil, which is considered a dielectric. Therefore, the magnetic radiation of the latter proceeds under conditions that are difficult to access to water globules.

If to take into account that during microwave radiation the volumetric heating of the WOE proceeds much faster than the WOE, then the reason for the intensive separation of the former becomes clear.

In Pic.2 a diagram of the movement of water globules in emulsions of various nature.

Figure 2. Diagram of localization of dispersed medium and phase in stable WOE and OWE:  I-stable WOE; II- stable OWE

It is known that the smaller the size of the particles (globules), the greater the degree of phase dispersion. Emulsions are usually considered coarse, with water globules up to 50 microns in size. Moreover, in WOE the size of the dispersed phase is 1.1-1.3 times greater than in OWE which is due to a change in the nature of the dispersed medium (water for oil) [9,10].

In the OTU, residuum is the main method of thermochemical dehydration and desalination of oil, where using the natural difference in the densities of oil and reservoir water, emulsion stratification is achieved. At the same time, sedimentation of mechanical impurities and the emergence of oil droplets on the surface of emulsions is ensured.

With microwave radiation of a stable WOE, the density of the dispersed medium changes in significantly, and vice versa, the OWE density of oil changes within significant limits. Hence, the rate of separation of the emulsion is observed higher if the size of water globule is larger and when the viscosity of the dispersed phase (oil) is the smallest [11,12].

It is clear from the above mentioned that to intensify this process, you need to know: the difference in phase densities, oil viscosity and the size of emulsified water droplets. The smaller the size of the water globules, the longer the phase separation time. Demulsifier used in practice increase the size of the globules, but this is not enough as residuum during thermochemical demulsification of oil takes more than 5 hours and even more. Affecting individual stages of the emulsion separation process, microwave radiation significantly intensifies them due to a decrease in viscosity and physicochemical as well as colloidal-chemical properties of WOE and OWE.

Conclusion. Thus, the systematic analysis of the operation of the oil preparation unit for industrial processing showed that in the course of dehydration and desalination of oil, WOE is converted into OWE, I.e. there is a sharp change in the nature of the dispersed medium and phase.

Moreover, in the thermochemical method of oil demulsification with the combined use of microwave radiation, the nature, composition and properties of the emulsion being separated should be considered. At the same time, the stage-by-stage analysis of the process of demulsification of oil by thermochemical and microwave methods makes it possible to scientifically substantiate the rational conditions and stages of their application.

It was revealed that the dehydration and desalination of the OWE is more complicated than the WOE which is due to the high viscosity of the dispersed medium of the former rather than the latter one.

For the demulsification of oil with a high-strength armor shell of water globules,it is recommended to use a combination of demulsifiers consisting of ionic and non-ionic surfactants and microwave radiation of separate stages of this process.

References:

1. Lutoshkin G.S. Sbor i podgotovka nefti, gaza i vody [Gathering of oil, gas and water treatment] // M.: PUBL Alliance. 2005.319 p.
2. Z.L. Ren, Y.H. Mou and F.Y. Cui, Mechanism and development trend of crude oil demulsifier, Oil-Gasfield Surface Engineering, 2005, 24, 16–17.
3. Shafiev R.U., Makhmudov N.N., Amirkulov N.S., Tursunov M.A., Bozorov Zh.T. Tekhnologiya sbora i podgotovki nefti, gaza i vody na promyslakh. [Gathering of oil, gas and water and treatment technology in the fields]. Textbook. - T.: Fan va technology, 2016 - 312 p.
4. Zhang, R.; Liang, C.; Wu, D.; Deng, S. Characterization and demulsification of produced liquid from weak base ASP flooding. Colloids Surf. A 2006, 290, 164–171.
5. Adizov B.Z., Razrusheniye vysoko mineralizovannykh emul'siy mestnykh neftey razrabotannymi deemul'gatorami v sochetanii s mikrovolnovym izlucheniyem [Destruction of highly saline emulsions of local oils by developed demulsifiers in combination with microwave radiation]. Diss. Cand. tech. sciences. - Tashkent, IONKh AN RUz, 2009.- 126 p.
6. Kafarov V.V., Metody kibernetiki v khimii i khimicheskoy tekhnologii [Methods of Cybernetics in Chemistry and Chemical Technology]. Moscow: Chemistry, 2004 - 478 p.
7. L.X. Liu, S.S. Hao, X.C. Wang, M.A. Jing and X.F. Zhao, Synthesis and demulsification of polyquaternium reverse demulsifier, Ind. Wastewater, 2010, 41, 70–73.
8. Nguyen, D.; Sadeghi, N. Stable emulsion and demulsification in chemical EOR flooding: Challenges and best practices. In Proceedings of the SPE EOR Conference at Oil and Gas West Asia, Muscat, Oman, 16–18 April 2012
9. Voyutsky S.S. Kurs kolloidnoy khimii [Colloidal chemistry course]. - M.: Chemistry - 1976 - 511p.
10. Kuznetsov V.V. Fizicheskaya i kolloidnaya khimiya [Physical and colloidal chemistry]. M.: Higher school, 1964 - 385 p.
11. Usmanov R.M., Abdikamalova A.B., Eshmetov I.D., Kuldasheva Sh.A., Eshmetov R.J., Sharipova A.I. Obtaining coal adsorbents based on local wood waste, research of their physico-chemical and adsorption properties Journal of Critical Reviews Vol 7, Issue 12, 2020 – P. 138-135.
12. Yang, F.; Tchoukov, P.; Qiao, P.Q.; Ma, X.; Pensini, E.; Dabros, T.; Czarnecki, J.; Xu, Z. Studying demulsification mechanisms of water-in-crude oil emulsions using a modified thin liquid film technique. Colloids Surf. A 2018, 540, 215–223.