CN107847816B

CN107847816B - Method of tuning radio frequency to break emulsions

Info

Publication number: CN107847816B
Application number: CN201680035527.5A
Authority: CN
Inventors: J·M·谢雷玛塔; P·N·斯莱特
Original assignee: ConocoPhillips Co
Current assignee: ConocoPhillips Co
Priority date: 2015-06-11
Filing date: 2016-06-10
Publication date: 2020-07-31
Anticipated expiration: 2036-06-10
Also published as: CN107847816A

Abstract

A method of determining an optimal radio frequency to break an emulsion, comprising: analyzing the oil-water interface of the emulsion; defining an oil-water interface at a molecular level; simulating the oscillation of molecules at the oil-water interface under different radio frequencies; and determining an optimal radio frequency to break the emulsion.

Description

Method of tuning radio frequency to break emulsions

Cross Reference to Related Applications

This application is a non-provisional application claiming priority from U.S. provisional application serial No.62/174,195 entitled "METHOD TO engine RADIO frequency devices TO break mu L sio," filed 2015, 6/11/35 USC, 119(e), the entire contents of which are incorporated herein.

Statement regarding federally sponsored research

None.

FIELD

The present disclosure relates to methods of tuning radio frequencies to break emulsions, and in particular to methods of determining an optimal radio frequency to break a crude oil emulsion.

Background

Emulsions are common in the oil and gas industry. Crude oil emulsions can be formed when water and oil are in contact with each other, particularly when there is sufficient mixing and a surfactant or emulsifier is present. For environmental and economic reasons, it is desirable to separate water from oil. The most common method of treating the emulsion is to apply heat and a suitable chemical emulsion breaker to promote instability of the emulsion film around the water droplets. However, chemical demulsifiers impose an economic burden. Demulsifiers also contaminate water sources and cause water treatment problems. Thus, the industry has always accepted an environmentally friendly and more cost effective method for breaking emulsions.

SUMMARY

In one embodiment, a method of determining an optimal radio frequency to break an emulsion comprises: analyzing the oil-water interface of the emulsion; defining an oil-water interface at a molecular level; simulating the oscillation of molecules at the oil-water interface under different radio frequencies; and determining an optimal radio frequency to break the emulsion.

In another embodiment, a method for determining an optimal radio frequency for breaking a water-in-oil emulsion comprises: separating molecules at an oil-water interface of the emulsion; analyzing the separated molecules to obtain chemical characterization data; creating a simulation cell (simulationcell) to define an interface at the molecular level; selecting at least one molecule separated from the oil-water interface for simulation; monitoring the rotation, transition or combination thereof of each selected molecule as a function of the radio frequency applied to the analog unit; and determining an optimal radio frequency to break the emulsion.

Electromagnetic energy having the determined optimal radio frequency may then be applied to the emulsion to break the emulsion.

Brief description of the drawings

The invention, together with further advantages thereof, may best be understood by reference to the following description, taken by way of example, and not by way of limitation, in conjunction with the accompanying drawings, in which:

FIG. 1 is a view of an atomic simulation unit of a crude oil brine emulsion;

FIG. 2 shows the total change in molecular angular momentum in an exemplary crude oil brine emulsion as a function of the frequency of the electric field; and

FIG. 3 shows the overall change in molecular diffusion in an exemplary crude oil brine emulsion as a function of the frequency of the electric field.

Detailed Description

Radio frequency heating is a promising technique for breaking emulsions in an environmentally friendly manner. However, the radio frequency must be fine-tuned. Otherwise, it does not effectively break or disrupt the emulsion.

Without wishing to be bound by theory, it is believed that the molecular dipoles oscillate in a constantly changing electromagnetic field. Each oil molecule in the emulsion has a specific optimal oscillation frequency. When the electric field oscillates at an optimal frequency, molecular motion is maximized. The resulting motion and heat disturb the interface, breaking the emulsion.

The inventors have thus developed a method of determining the optimum radio frequency to break the emulsion. As used herein, "optimal radio frequency" refers to a radio frequency that is most likely to trigger the greatest effect on molecules at the oil-water interface of an emulsion. The optimum radio frequency is not limited to a fixed value and may include a radio frequency range.

This approach minimizes the cost that may be required to determine an effective way to break the emulsion. It may be suitably used to determine the optimal radio frequency to break a wide variety of emulsions, including but not limited to producing emulsions on surfaces and in interfaces. In one embodiment, the emulsion is a water-in-crude oil emulsion containing from about 1 to about 60 volume percent water. As used herein, water refers to the aqueous phase and includes brine.

Emulsions may comprise a dispersed phase and a continuous phase, wherein the boundary between the phases is referred to as the "interface". Although the emulsion may include a variety of ingredients, such as inorganic fine particles, non-polar and polar resins, asphaltenes, naturally occurring and synthetic surfactants, the composition of the interface plays an important role in stabilizing the emulsion. Thus, analysis of the composition at the interface can provide information for determining the optimal radio frequency for breaking the emulsion.

Analysis of the oil-water interface involves separating molecules at the interface and characterizing the separated molecules. Separation methods are known in the art and include extraction, distillation, chromatography, centrifugation, crystallization, filtration, flotation, and the like. Characterization methods are not limited and include Nuclear Magnetic Resonance (NMR) spectroscopy, mass spectrometry, elemental analysis, simulated distillation, and fourier transform infrared spectroscopy. Other methods known in the art may also be used. The chemical characterization data includes a structure, a formula, a molecular weight, or a mole percent of the isolated molecule, or a combination comprising at least one of the foregoing. In one embodiment, the molecular structure of the isolated molecule is determined.

It is understood that not all compounds at the interface must be separated due to the presence of equivalent features or functional groups. In one embodiment, the isolated compound comprises asphaltenes and a surfactant, such as alkyl benzene sulfonate. Sodium dodecylbenzenesulfonate may be mentioned specifically. Known information about compounds that are normally present in the interface of crude oil and aqueous emulsion can also be used.

A model may then be created based on the obtained chemical characterization data to define the emulsion interface at the molecular level. The likelihood of local ordering, such as molecular packing and orientation, may be taken into account when building the model. E.g. from Materials

Is/are as follows

Tools of the amorphus manufacturer can be used to create models, such as simulation units. Figure 1 illustrates the atomic simulation unit of a crude oil brine emulsion.

Once the model is established, the molecules can be simulated for oscillation at the oil-water interface at different radio frequencies. The molecules separated from the emulsion interface may include non-polar resins or asphaltenes that are free of heteroatoms such as oxygen, nitrogen and sulfur. These nonpolar molecules have small or zero dipoles. Thus, the dielectric field may not directly affect these molecules, but through the motion of adjacent polar molecules. In one embodiment, a set of molecules is selected for oscillation simulation. The molecules selected are those that are more likely to respond to an electric field. For example, the selected molecule has a high dipole or is polar.

Quantum mechanical simulation of dipole oscillation can be performed for each selected molecule. During simulation, an external radio frequency field is applied to the simulation cell to study molecular motion, i.e., rotation and transitions, as a function of radio frequency. The external radio frequency may be about 500kHz to about 500 MHz. In one embodiment, the simulation is conducted under an external electrical radio frequency field at a frequency of about 0.5, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, or even about 500 MHz. Other frequencies in the range of about 500KHz to about 500MHz may also be used.

In the case where the oil/water emulsion model is not uniform along the x, y and z axes, the electric field may be applied along the x, y and z axes, respectively, and thus the average of the rf electric field effects is compounded.

Electric field strength of about

To about

In particular about

To about

Without being bound by theory, it is believed to have

Or a greater strength of the electric field may result in a rather unrealistic diffusion of molecules, i.e. the molecules break beyond the electric field point. For the

Or less, has a negligible effect on the mean square shift and may be misled by statistical noise.

If desired, the system can be pre-balanced without an external electric field before applying an electric field of the desired frequency and intensity. The molecular mean square displacement and angular momentum may be used, for example, from Materials

Obtained by

The tool, L AMMPS, etc., samples within a few nanoseconds along one axis this simulation is performed similarly along the other two axes.

The angular momentum and mean square displacement on the selected molecules before and after the application of the electric field can be compared. Once the changes in angular momentum and mean square displacement on each selected molecule are determined, the average of these values is calculated to determine the optimal radio frequency to break the emulsion. The total change in molecular angular momentum in an exemplary crude oil-water emulsion as a function of electric field frequency is shown in FIG. 2. The overall change in molecular diffusion in an exemplary crude oil water emulsion as a function of electric field frequency is shown in FIG. 3. In fig. 3, the diffusion variation is represented as a ratio of diffusion in the presence and absence of an external electric field. Based on the results of fig. 2 and 3, the optimal radio frequency to break the exemplary emulsion is about 10 to about 15 MHz.

The optimal radio frequency obtained from this process can be used in the art to break emulsions. It can also be used later in pilot/laboratory tests to minimize cost. Correlation models can also be used to determine the optimal Radio Frequency (RF) based on molecular descriptors. Once established, the model can be used to calculate the optimal RF from the molecular descriptors, rather than using values for a particular molecular configuration for actual simulation.

All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. "or" means "and/or". As used herein, "combination" includes blends, mixtures, alloys, reaction products, and the like. All references are incorporated herein by reference.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The modifier "about" used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).

While typical embodiments have been set forth for the purpose of illustration, the foregoing descriptions should not be deemed to be a limitation on the scope herein. Accordingly, various modifications, adaptations, and alternatives may occur to one skilled in the art without departing from the spirit and scope herein.

Claims

1. A method of determining an optimal radio frequency to break an emulsion, the method comprising:

analyzing the oil-water interface of the emulsion;

defining an oil-water interface at a molecular level;

simulating the oscillation of molecules at the oil-water interface under different radio frequencies; and

the optimal radio frequency to break the emulsion is determined.

2. The method of claim 1, wherein analyzing an oil-water interface comprises separating molecules at the interface and characterizing the separated molecules.

3. The method of claim 2, wherein the molecule is isolated by one or more of the following methods: extraction, distillation, chromatography, centrifugation, crystallization, filtration or flotation.

4. The method of claim 2, wherein the isolated molecule comprises at least one of asphaltenes and surfactants.

5. The method of claim 2, wherein the isolated molecule is characterized by one or more of the following methods: nuclear magnetic resonance spectroscopy, mass spectroscopy, elemental analysis, simulated distillation or fourier transform infrared spectroscopy.

6. The method of claim 2, wherein characterizing the isolated molecules comprises obtaining chemical characterization data comprising at least one of: chemical structure, chemical formula, molecular weight, or mole percent of molecules separated in the interface.

7. The method of claim 1, wherein defining the oil water interface at a molecular level comprises creating an analog cell.

8. The method of claim 1, wherein the molecules at the oil-water interface are polar molecules separated from the water-oil interface.

9. The method of claim 1, wherein simulating oscillations comprises monitoring molecular rotations and transitions at the oil-water interface as a function of radio frequency.

10. The method of claim 9, wherein monitoring the rotation and transition of the molecule comprises determining the angular momentum or mean square displacement of the molecule before and after applying the radio frequency to the simulation cell.

11. The method of claim 1, wherein the radio frequency is about 500KHz to about 500 MHz.

12. The method of claim 1, wherein the radio frequency comprises about 0.5, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, or 500 MHz.

13. The method of claim 1, wherein determining an optimal radio frequency comprises calculating an average of angular momentum changes or an average of mean square displacement changes before and after applying the radio frequency.

14. The method of claim 1, wherein the emulsion is a water-in-crude oil emulsion.

15. A method of determining an optimal radio frequency to break a water-in-oil emulsion, the method comprising:

separating molecules at an oil-water interface of the emulsion;

analyzing the separated molecules to obtain chemical characterization data;

creating a simulation unit to define an interface at a molecular level;

selecting at least one molecule separated from the oil-water interface for simulation;

monitoring the rotation, transition or combination thereof of each selected molecule as a function of the radio frequency applied to the analog unit; and

the optimal radio frequency to break the emulsion is determined.

16. The method of claim 15, wherein the isolated molecule comprises at least one of asphaltenes and surfactants.

17. The method of claim 15, wherein monitoring the rotation and transition of the molecule comprises determining the angular momentum or mean square displacement of the molecule before and after applying the radio frequency to the simulation cell.

18. The method of claim 15, wherein the radio frequency applied to the analog unit is about 500KHz to about 500 MHz.

19. The method of claim 15, wherein the radio frequency applied to the analog unit comprises about 0.5, 5, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, 350, 400, 450, or 500 MHz.

20. A method of breaking an emulsion, the method comprising:

determining an optimal radio frequency for breaking the emulsion according to the method of claim 1; and

electromagnetic energy having a determined frequency is applied to the emulsion.

21. A method of breaking an emulsion, the method comprising:

determining an optimal radio frequency to break the emulsion according to the method of claim 15; and