METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF

Abstract

The present invention addresses to a method for analyzing and detecting solids in emulsions, oil and derivatives thereof even in the presence of high contents of water (>5% v/v), which is based on the absorption and scattering of light by solids suspended in solution.

The application of the method of this invention contributes to greater reliability in terms of control of BSW (oil quality) and OGC (water to be treated and discarded). Additionally, there is the possibility of controlling the dosage of products such as scale inhibitors and naphthenates inhibitors, optimizing the dosage and minimizing operational occurrences associated with the formation of deposits. These eventually lead to equipment clogging throughout the process.

Claims

1- A METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF, characterized in that it comprises the following steps: (a) Homogenizing the emulsion or oil sample for one minute under strong manual agitation; (b) Next, transferring part of the sample to a wide mouth flask and, with the aid of a syringe, transferring from 0.5 to 5 mL to a volumetric flask; (c) Transferring a binary mixture of solvents X into the volumetric flask. The added volume of solvent mixture X must be 60% of the capacity of the volumetric flask; (d) Manually agitating the resulting Y mixture for 1 minute and placing the same in an ultrasound system for 10 minutes; (e) Allowing the solution to stand until it reaches room temperature; (f) Next, filling up the volumetric flask containing the mixture Y with the mixture of solvents X and performing its homogenization; (g) Next, taking an aliquot of the mixture Y to read the absorbance in a photometer, using a measuring cell or cuvette; (h) Taking the absorbance reading at a defined wavelength in the ultraviolet-visible region, using the solvent mixture X as a blank for the absorbance reading; (i) Taking a new aliquot of the mixture Y with the aid of a syringe to perform its filtration; (j) Attaching a disposable filter to this syringe containing the mixture and proceed to filtration with the collection of the filtered solution Z, in which the volume must be enough to fill the measuring cell or cuvette used for absorbance reading; (k) Performing the absorbance reading of the filtered solution Z under the same conditions and in the same photometer used for the analysis of the mixture Y; (l) Determining the solids content from a calibration curve, through the difference of the absorbance of the mixture Y minus that of the filtered solution Z, which corresponds to the absorbance delta (A Abs); (m) Determining the concentration of solids in the mixture Y and calculate the solids content in the sample from the dilution factor of the mixture Y.

2- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the binary mixture of solvents X is composed of an aromatic solvent (toluene, p-xylene, o-xylene, p-xylene, xylenes, among others) and an oxygenate of the glycol class (ethylene glycol, butyl glycol, among others), whose concentration of the oxygenated solvent varies from 20 to 80% (v/v).

3- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the measuring cell or cuvette has an optical path of at least 10 millimeters.

4- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the disposable filter is of the syringe type and has a defined pore size between 0.45 and 8 μm.

5- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the dilution factor is the ratio between the capacity of the volumetric flask used in the preparation of the mixture Y and the volume of sample used in the analysis.

6- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the concentration of solids in the sample is the product of the solids content in the mixture Y and the calculated dilution factor.

7- THE METHOD FOR ANALYSIS AND DETECTION OF SOLIDS IN EMULSIONS, OIL AND DERIVATIVES THEREOF according to claim 1, characterized in that the samples present water contents above 5% v/v.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be described in more detail below, with reference to the attached figures which, in a schematic way and not limiting the inventive scope, represent examples of its embodiment. In the drawings, there are:

[0017] FIG. 1 illustrating UV-visible absorption spectra of a diluted sample solution before (solid line) and after filtration (dotted line);

[0018] FIG. 2 illustrating an example of a calibration curve correlated to the concentration of solids in the solution as a function of the absorbance delta (A Abs).

DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention describes a fast method for analyzing solids in samples of emulsions, oil and derivatives thereof, which is based on the absorption and scattering of light by solids suspended in solution. The method allows the measurement of solids in complex organic samples such as oil, even in the presence of high contents of water (>5% v/v).

[0020] The light scattering technique is widely used for the quantification of solids in water, but it has strong limitations regarding its use for organic samples, and even more so for oil, because it is dark (low light transmission) and due to the presence of emulsified water. The water droplets emulsified in the oil also cause light scattering, making it impossible to measure solids using this analytical technique, especially in samples with water content greater than 1% v/v.

[0021] In addition, the procedures available for measuring solids in oil and emulsions are based on time-consuming gravimetric methods, whose tests can only be carried out in onshore laboratories, which requires disembarking the sample from the offshore platform.

[0022] Another feature associated with the present invention is the use of a mixture of solvents, which clarifies the medium and allows the dispersion of oil and emulsified water, thus enabling the transmission of light and, consequently, the measurement of absorption and scattering by solids in suspension.

[0023] Further, according to this invention, the calibration curve for quantification of solids is constructed from the variation in absorbance of dispersions of known concentrations of solids in oil, obtained by applying the method of the present invention. This analytical approach makes it possible to measure solids in oil in an offshore environment, even in the presence of high contents of water (>5% v/v).

[0024] Traditional methods of quantification of solids in this type of sample are performed only in onshore laboratories, which requires disembarking the sample, with a reasonably long time to obtain results. The advantage of the method of the invention is the use of simple, compact and low-cost instrumentation, which makes it possible to quickly perform analyzes in offshore laboratories.

[0025] The solids content is proportional to the difference in the intensity of light absorption (absorbance) of the diluted sample solution, read at a given wavelength of the ultraviolet-visible spectrum, before and after filtration. The absorption of this solution before filtration corresponds to the sum of the absorptions of the insoluble parts and the soluble parts in the solvent plus the fraction of the light scattered by the insoluble parts accounted for as absorbance; meanwhile, the light absorbed by the filtration product is related exclusively to the soluble parts.

[0026] The difference in the absorbance value under these conditions (before and after filtration), called delta (A) of absorbance, is attributed to the solids present in the sample. FIG. 1 presents absorption spectra in the ultraviolet-visible region and the difference between the absorptions, indicated in the figure as A Abs.

[0027] As the absorbance delta (A Abs) is proportional to the concentration of solids in the solution, it is possible to calculate their content in the oil and/or emulsion from a calibration curve. For this, it is necessary to prepare dispersions with known concentrations of solids in oil and to apply the analysis method of the present invention.

[0028] FIG. 2 shows an example of a calibration curve. From this, it is possible to calculate the solids content (T), using the equation below:

T=(Δ Abs×631.47)−6.6312  Eq

where:
T=solids content in the diluted solution (mg/L).

[0029] To calculate the concentration of solids in the sample, use the equation below:

C=T×F  Eq.2

Where:

[0030] C=concentration of solids in the sample (mg/L);
T=solids content in the diluted solution (mg/L);
F=sample dilution factor.

[0031] Knowing the density of the sample, the concentration of solids can also be reported in % mass, using equation 3 below:

[00001]$\begin{array}{cc}C=\frac{T\times F}{10000\times D}& \mathrm{Eq}.3\end{array}$

Where:

[0032] C=concentration of solids in the sample (mg/L);
T=solids content in the diluted solution (mg/L);
F=sample dilution factor;
D=oil density (g/mL).

[0033] The method for analysis and detection of solids in samples of emulsions, oil and derivatives thereof comprises the following steps: [0034] (a) The emulsion or oil sample is homogenized for one minute under strong manual agitation; [0035] (b) Next, part of the same is transferred to a wide mouth flask and, with the aid of a syringe, 0.5 to 5 mL of the sample is transferred to a volumetric flask; [0036] (c) A binary mixture of solvents X, an aromatic one (toluene, p-xylene, o-xylene, p-xylene, xylenes, among others) and an oxygenate of the class of glycols (ethylene glycol, butyl glycol, among others), whose concentration of the latter varies from 20 to 80% (v/v), is transferred to the volumetric flask. The concentration of the oxygenated solvent in the solvent mixture must be sufficient to solubilize the water in the oil. The added volume of solvent mixture X must be about 60% of the capacity of the volumetric flask; [0037] (d) The resulting mixture Y is manually agitated for 1 minute and taken to an ultrasound system for 10 minutes to aid in the solubilization of the sample in the solvent mixture X; [0038] (e) The solution is then allowed to stand until it is at room temperature; [0039] (f) Next, the volumetric flask containing mixture Y is filled with solvent mixture X and homogenized; [0040] (g) Next, an aliquot of the Y mixture is taken to read the absorbance in a photometer, using a measuring cell or cuvette with an optical path of at least 10 millimeters; [0041] (h) The absorbance reading is performed at a defined wavelength in the ultraviolet-visible region, using the mixture of solvents X with the absorbance reading blank; [0042] (i) A new aliquot of mixture Y is taken with the aid of a syringe to perform its filtration; [0043] (j) A syringe-type disposable filter is attached to this syringe containing the mixture, with a pore size between 0.45 and 8 μm, and filtration is carried out with the collection of the filtered solution Z. The volume must be enough to fill the cuvette used for absorbance reading; [0044] (k) The absorbance reading of the filtered solution Z is then taken under the same conditions and in the same photometer used for the analysis of the mixture Y; [0045] (l) The difference in the absorbance of the mixture Y minus that of the filtered solution Z corresponds to the absorbance delta (Δ Abs), and this is attributed to the solids present in the sample, whose concentration can be calculated from a calibration curve such as exemplified in FIG. 2; [0046] (m) By determining the concentration of solids in the mixture Y, it is possible to calculate the solids content in the sample from the dilution factor of the mixture Y. The dilution factor is the ratio between the capacity of the volumetric flask used in the preparation of the mixture Y is the sample volume used in the analysis; [0047] (n) The solids concentration in the sample is the product of the solids content in the mixture Y and the calculated dilution factor.

Examples

[0048] The following examples are presented in order to more fully illustrate the nature of the present invention and the way to practice the same, without, however, being able to be considered as limiting its content.

[0049] Field analyzes were carried out in a refinery and offshore production platform from samples collected at desalter interfaces and separation vessels respectively (in a field laboratory). Additionally, samples were also collected for analysis at an external laboratory and the obtained results were compared. Adherence was observed between the obtained data, making it possible to obtain a solids distribution profile along the vessel or desalter.

[0050] In addition, collections were carried out on different dates, making it possible to verify sensitivity in terms of variation and influence of operational actions in changing the amounts of solids observed. The same type of comparison was also extended to oil samples, with good correlation between measurement via gravimetry and the approach of the present invention.

[0051] Table 1 below presents, as an example, the comparison of results of the quantification of solids by gravimetry (traditional method) and the method proposed in the present invention.

TABLE-US-00001 TABLE 1 Results of the quantification of solids in emulsion and oil samples by the traditional gravimetric method and by the method of the present invention. Sample Type Emulsion Emulsion Emulsion Emulsion Oil Oil Gravimetry 0.3 0.3 1.1 0.4 0.2 0.1 (% mass) Proposed 0.4 0.3 1.0 0.6 0.2 0.1 method (% mass)

[0052] It should be noted that, although the present invention has been described in relation to the attached drawings, it may undergo modifications and adaptations by technicians skilled on the subject, depending on the specific situation, but provided that within the inventive scope defined herein.