Method for analysing additives used during petroleum extraction

Abstract

The present disclosure relates to the use of a high performance liquid chromatography (HPLC) or ultra-high performance (UHPLC) process, coupled to a high resolution mass spectrometry (HRMS) process.

Description

METHOD FOR ANALYZING ADDITIVES USED IN OIL PRODUCTION technical field

[0001] This disclosure relates to the field of petroleum exploitation. In particular, this disclosure concerns a method for analyzing additives used in petroleum exploitation using a high-performance liquid chromatography (HPLC) or ultra-high-performance liquid chromatography (UHPLC) process, coupled with a high-resolution mass spectrometry (HRMS) process. Technological background

[0002] During oil and gas field development, oil and gas recovery can be improved by injecting water into the reservoir through an injection well. This forces the oil out of the reservoir via at least one other well, known as a production well. The interaction of the injected water with the reservoir containing the gas, oil, and groundwater can result in the formation of chemical species that may cause malfunctions in the facilities.

[0003] For example, mineral deposits or corrosion can occur under various operating conditions in industrial facilities in contact with an aqueous environment. To prevent or slow these phenomena, additives are injected, for example, into underground formations or into gas or oil wells. Examples of such additives include mineral deposit inhibitors and corrosion inhibitors. Injecting a fluid containing an inhibitor capable of preventing the formation of problematic crystals, inhibiting their growth, or dispersing them helps to counteract the aforementioned drawbacks and avoid or delay the dismantling of facilities for cleaning.

[0004] Other types of additives, such as surfactants, antifoaming agents, demulsifiers, or bactericides, may also be used in oil production. Therefore, production waters generally contain a wide variety of additives.

[0005] The dosage (detection and / or quantification) of these additives is an essential aspect of hydrocarbon production, in order to ensure that they are present in sufficient quantity to fulfill their function and, if necessary, to inject in a timely manner an additional quantity of additive, adjusted to take into account the economic constraints of the process and its environmental impact.

[0006] The methods currently used to dose these additives are often unreliable and / or time-consuming and require equipment that is often insufficiently adapted to operating conditions.

[0007] The development of a reliable and accurate detection method is further hampered by the fact that these additives are generally so effective that they are present in the injected fluid at a level of only a few ppm, and by the presence in the fluid made up of operating waters of a variety of compounds such as salts and organic residues.

[0008] It would therefore be desirable to be able to detect and / or measure these additives in production waters, using a simple, reliable and precise method, usable on a variety of additives. Summary

[0009] This disclosure improves the situation. The purpose of this disclosure is a method for analyzing additives used in petroleum production using a high-performance liquid chromatography (HPLC) or ultra-high-performance liquid chromatography (UHPLC) process coupled with a high-resolution mass spectrometry (HRMS) process. This method comprises the following steps: a. Injecting into an HPLC or UHPLC column a volume of an aqueous fluid sample containing at least one additive used in petroleum production. The column contains silica-based particles grafted with octadecyl groups, each octadecyl group being linked by at least two attachment points to the silica particles via Si-C bonds; b. Eluding with a mobile phase; and c. Detecting the additives by HRMS.

[0010] This method allows for the separation, identification, and quantification, using HPLC-HRMS or UHPLC-HRMS, of additives used in the petroleum industry in production water (complex matrix), without prior knowledge of the nature of all the compounds present in the additive, down to concentrations of 1 pg / g, or 1 ppm. In particular, it allows for the separation, identification, and quantification of corrosion inhibitors comprising species with diverse chemistries (quaternary ammonium compounds, imidazolines, carboxylic acids, phosphoric esters) in production water, without sample pretreatment.

[0011] The use of a column containing silica-based particles grafted with octadecyl groups, each octadecyl group being linked to the silica particles by at least two Si-C bonds, allows for the untargeted analysis of additives used in petroleum production, particularly corrosion inhibitors. This column provides excellent separation. This type of column is suitable for a large proportion of additives commonly used in petroleum production, and high-resolution mass spectrometry enables the analysis and detection of many compounds. Furthermore, thanks to the equipment used, it allows for the analysis of production water without pre-injection sample treatment, thus minimizing manipulations and experimental errors. Therefore, it is possible to perform untargeted analyses without pre-injection sample treatment.

[0012] The present method is versatile enough to analyze a wide range of molecules with different chemical functions. Brief description of the drawings

[0013] Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: Fig. 1

[0014] [Fig. 1a] shows an elution gradient used in the UHPLC method of Examples 1 and 2 and [Fig. 1b] shows another elution gradient that can be used in the method of the present disclosure. Fig. 2

[0015] [Fig. 2] shows the schematic of the UHPLC and HRMS setup used for the analysis. Fig. 3

[0016] [Fig. 3] shows a superposition of ion chromatograms extracted from model mixtures in water, according to the examples. Fig. 4

[0017] [Fig. 4] shows a superposition of normalized extracted ion chromatograms of molecules present in the mixture with additive A according to example 1. Fig. 5

[0018] [Fig. 5] shows a superposition of ion chromatograms extracted from molecules in the distribution with an 8-carbon alkyl chain in the mixture with additive B according to example 2. Fig. 6

[0019] [Fig. 6] shows a superposition of ion chromatograms extracted from molecules in the distribution with a 10-carbon alkyl chain in the mixture with additive B according to example 2. Detailed description

[0020] The purpose of this disclosure is to describe a method for analyzing additives used in petroleum production using a high-performance liquid chromatography (HPLC) or ultra-high-performance liquid chromatography (UHPLC) process coupled with a high-resolution mass spectrometry (HRMS) process, said method comprising the following steps: a. Injecting into an HPLC or UHPLC column a volume of an aqueous fluid sample comprising at least one additive used in petroleum production, said column containing silica-based particles grafted with octadecyl groups, each octadecyl group being linked by at least two attachment points to the silica particles by Si-C bonds, b. Eluding with a mobile phase, and c. Detecting the additives by HRMS.

[0021] HPLC is a well-known analytical separation technique. The injected sample volume is eluted with a mobile phase in a column packed with a stationary phase (silica-based particles). UHPLC is a type of HPLC where the particle size of the stationary phase (silica particles) is very small, for example, less than 2 µm. HRMS is HRMS is based on mass spectrometry, an analytical technique used to detect compounds by measuring their mass. It provides high-resolution mass measurement. The HPLC, UHPLC, and HRMS devices that can be used in this disclosure are those commonly employed.

[0022] Additives used in oil production can be any type of additive commonly used in oil and gas exploration or production. In one embodiment, the additives to be detected are selected from corrosion inhibitors, demulsifiers, bactericides, hydrate kinetic inhibitors (including hydrate anti-caking agents), mineral deposit inhibitors, antifoaming agents, and mixtures thereof. Preferably, the additives to be detected are selected from corrosion inhibitors, demulsifiers, and hydrate anti-caking agents.

[0023] This method allows its use on a wide range of additives with different chemical functions. The chemical nature of the additives to be detected can therefore vary considerably. For example, the additives to be detected can be chosen from among amines, ammonium compounds, phosphate esters, oxazolidines, imidazolines, polyethyleneimines, carboxylic acids, sulfates, sulfonates, ethylene or propylene oxides, and mixtures thereof.

[0024] The additives to be detected can be selected from the group consisting of - polyphosphates, such as sodium tripolyphosphate (STPP), sodium hexametaphosphate (SHMP), - phosphate esters, such as mono-, di- and triester phosphates, for example a monoester of formula (OH)2P(=O)OR, R being preferably an alkyl or heteroalkyl group, - organophosphonates, such as amino tri(methylene phosphonic acid) or AMP, 1-hydroxyethylidene-1,1-diphosphonic acid or HEDP, ethylenediamine tetra(methylene phosphonic acid) or EDTMP, hexamethylenediamine tetra(methylene phosphonic acid) or HMTMP, diethylenetriamine penta(methylene phosphonic acid) or DETMP, hydroxyethylamino-di(methylenephosphonic acid) (HEMPA) - Carboxylic acids and polycarboxylic acids such as 2-phosphonobutane 1,2,4-tricarboxylic acid or PBTC, poly(acrylic acid) or PAA, poly(methacrylic acid) or PMAA, poly(maleic acid) or PMA - polymers with sulfonic acid function, such as styrene sulfonic acid and (poly)carboxylic acid copolymers, in particular styrene sulfonic acid and maleic acid copolymers, styrene sulfonic acid and (poly)amidoamine copolymers, vinylsulfonate homo- and copolymers, in particular vinylsulfonate, styrene and maleic anhydride copolymers, alkyldiphenyl ether sulfonates and acrylamidomethylpropane sulfonic acid (AMPS), maleic acid and acrylic acid copolymers, - polyphosphinocarboxylic acid (PPCA), possibly sulfonated - polyethyleneimines (PEI) and polyethyleneamines - silicone polymers, in particular polydimethylsiloxanes, functionalized by groups amines, - quaternary ammonium-based copolymers, such as acrylamide, quaternary ammonium and possibly acrylate copolymers, and acrylamide, diallyldimethylammonium salt and possibly acrylate copolymers - amines and polyamines such as mono-, di- and triamines, cyclic or non-cyclic, such as cyclohexylamine, hexylamine, morpholine, oxazolidines, imidazolines, piperazines, piperimidines, or octadecylamine, - amino alcohols such as diethylaminoethanol, - quaternary ammonium compounds, - imines and iminiums, - sulfates, - sulfonates, - ethylene or propylene oxides, - betaines, and - their mixtures.

[0025] According to one embodiment, the additives to be detected can be selected from the group consisting of - quaternary ammonium compounds, - carboxylic acids, - amines, - polyamines, - phosphate esters, such as mono-, di- and phosphate triesters, and - their mixtures.

[0026] According to one embodiment, the quantity of additives to be detected in the sample is between 0.5 pg / g of sample and 5 mg / g (i.e. between 0.5 and 5000 ppm), preferably between 1 pg / g and 500 pg / g, and more preferably between 1 pg / g and 100 pg / g.

[0027] The aqueous fluid sample can be a sample of production water, injection water, or industrial effluent. Preferably, the aqueous fluid sample is a sample of production water or injection water.

[0028] The production or injection water sample may not require any pretreatment before injection into the HPLC or UHPLC column. This makes the method faster and simpler to implement. No pretreatment is required if the aqueous fluid sample does not contain a particulate phase. If the sample contains a particulate phase, filtration may be necessary before injection. The injected sample volume can range from 0.5 to 100 pL, or from 1 to 50 pL.

[0029] According to one embodiment, the aqueous fluid sample contains a high salt content, for example at least 10 g / L. The sample may, for example, contain calcium, iron, potassium, lithium, magnesium, and strontium ions. Even when the sample contains a high salt content For salt, pretreatment of the sample to remove salt is unnecessary. A multi-way valve can be placed between the chromatography column outlet and the mass spectrometer, allowing a portion of the sample to be removed before passing through the mass spectrometer (see Fig. 2). This enables the direct analysis of production water samples, which is generally not possible with other methods, as the salts contained in this production water are incompatible with mass spectrometry. Matrix effects were observed but did not prevent analysis: separation remained good despite slightly broader peaks, and the compounds remained detectable by mass spectrometry at the concentrations considered.

[0030] The apparatus used to implement the method of this disclosure is shown in Figure 2. The injected sample volume is eluted with a mobile phase in the column (1), and then an optional valve (2) allows the eluted sample to be discarded if necessary, for example, during the first few minutes of elution if the sample has a high salt content. This allows a portion of the sample to be discarded, for example, during the first few minutes of elution, by sending it to the waste container (3). The eluted sample then passes through a T-fitting (4) which allows a portion of the eluted sample to be discarded by sending it to the waste container (5) to limit the flow of mobile phase reaching the ionization source (6), which ionizes the compounds present. These compounds are then analyzed by the HRMS device (7).

[0031] The use of a multi-way valve, for example, 3, 4, 5, or 6-way, is particularly advantageous when the sample is a production water sample with a high salt content. The sample may then contain one or more of the following salts: NaCl, CaCh, MgCh, Na4BOz, KG, BaCh, KBr, LiCl, NaHCOs, and Na2SO4. The concentration of each salt can be extremely variable depending on the production water, ranging from 1 mg / L to several hundred g / L, for example, up to saturation. Since the sample is an aqueous fluid, the presence of salts results in the presence of ions in the sample, such as one or more of the following ions: K + ,N / A + , Mg 2+ , That 2+ , Sr 2+ Ba 2+ , CO3 2 ; HCOs", NOs", F, Cf, Br, SCU 2- and PCU 2- . As with salt content, ion content is extremely variable and can range from 1 mg / L to several hundred g / L.

[0032] The HPLC or UHPLC column contains silica-based particles grafted with octadecyl groups (C18), each octadecyl group being linked to the silica particles by at least two Si-C bonds. Each octadecyl group may, for example, have two or three Si-C bonds attached to the silica particles. In one embodiment, each octadecyl group has three Si-C bonds attached to the silica particles. The column used has reversed phase polarity. Examples of columns suitable for this method include Waters Acquity HSS T3 Premier, Cogent Bidentate C18, and Zorbax Extend C18.

[0033] The column may also have been treated against adsorption, which allows for reduced interaction with silanols.

[0034] In one embodiment, the size of the silica-based particles is between 2 and 5 µm. The size of the silica-based particles can also be less than 2 µm; in this case, it is a UHPLC-type column. This allows for excellent separation.

[0035] According to one embodiment, the pore size of the silica-based particles is between 75 Å and 120 Å, preferably between 85 Å and 110 Å.

[0036] The mobile phase used to elute the sample may include: - a mobile phase A comprising water and a water-miscible organic solvent, preferably an alcohol, in a ratio of between 99:1 and 90:10, said mobile phase A optionally comprising an acid, preferably between 0.1 and 10% v / v; and - a mobile phase B comprising water and an alcohol, at a ratio between 1:99 and 10:90.

[0037] The water-miscible organic solvent may be chosen from methanol, ethanol, propanol, acetonitrile, and mixtures thereof. Preferably, the miscible solvent is methanol.

[0038] Mobile phase A and / or mobile phase B may include an acid. The acid used is a Brønsted acid, i.e., a proton donor. It may be chosen, for example, from formic acid, acetic acid, and trifluoroacetic acid. Formic acid is preferably used. Its concentration may be between 0.1 and 10% v / v, for example, between 0.5 and 5% v / v.

[0039] Steps a) and b) of the process can be carried out at a temperature between 10 and 30°C, preferably at a temperature between 15 and 25°C.

[0040] The mobile phase used to elute the sample may include: - a mobile phase A comprising water and methanol in a ratio between 99:1 and 90:10, and - a mobile phase B comprising water and methanol in a ratio between 1:99 and 10:90.

[0041] According to one embodiment, mobile phase A comprises a mixture consisting of 95% v / v water and 5% v / v methanol, to which is added 0.1% v / v formic acid, of purity greater than 99%, and mobile phase B comprises a mixture consisting of 5% v / v water and 95% v / v methanol, to which is added 0.1% v / v formic acid, of purity greater than 99%.

[0042] In one embodiment, a gradient elution can be used with at least 40% of mobile phase B, up to 100% of mobile phase B, before returning to the initial percentage of mobile phase B. Prior to gradient elution, isocratic elution can be performed. This isocratic elution can be carried out for several minutes.

[0043] According to one embodiment, the gradient may be as follows: the gradient starts with 75% of mobile phase B. Between 0 and 2 minutes, the amount of mobile phase B increases linearly from 75% to 80%. Between 2 and 4 minutes, a plateau is reached at 80% of mobile phase B. Between 4 and 9 minutes, the amount of mobile phase B increases linearly from 80% to 90%. Between 9 and 10 minutes, the amount of mobile phase B increases linearly from 90% to 100%. Between 10 and 13 minutes, a plateau is reached at 100% of mobile phase B. Between 13 and 14 minutes, the amount of mobile phase B decreases linearly from 100% to 75%. Between 14 and 19 minutes, a plateau is reached. carried out at 75% mobile phase B, in order to rebalance the column. This gradient is shown in Figure 1a.

[0044] According to another embodiment, isocratic elution is performed for 2 minutes with 50% of mobile phase B, and then the elution gradient is as follows: Between 2 and 3 minutes, the amount of mobile phase B increases linearly from 50% to 75%. Between 3 and 5 minutes, the amount of mobile phase B increases linearly from 75% to 80%. Between 5 and 7 minutes, a plateau is reached at 80% of mobile phase B. Between 7 and 12 minutes, the amount of mobile phase B increases linearly from 80% to 90%. Between 12 and 13 minutes, the amount of mobile phase B increases linearly from 90% to 100%. Between 13 and 16 minutes, a plateau is reached at 100% of mobile phase B. Between 16 and 17 minutes, the amount of mobile phase B decreases linearly from 100% to 30%. Between 17 and 22 minutes, a plateau is achieved at 50% mobile phase B, in order to re-equilibrate the column. This gradient is shown in Figure 1b.

[0045] After passing through the chromatography column, a step is performed to detect additives using high-resolution mass spectrometry (HRMS). The preferred ionization method is electrospray ionization (ESI), which can be performed in positive or negative mode. This type of ionization is commonly used in combination with liquid chromatography. The analyzer used is preferably an Orbitrap (orbital trap mass spectrometer).

[0046] According to one embodiment, the RP resolving power of the mass spectrometer is at least 10000 FWHM at m / z 200, preferably at least 100000.

[0047] High-resolution mass spectrometry makes it possible to analyze molecules as different as quaternary ammonium compounds and phosphoric esters with a very low detection limit, for example down to 1 ppm. Examples

[0048] Two commercially available anti-corrosion additives used in oil production were tested, A and B.

[0049] Initially, various columns were tested on model mixtures: Accucore C18, CORTECS Shield RP 18, Acquity HSS T3 Premier, Acquity HSS T3, Cogent Bidentate C18, Accucore C4, Synergi Polar RP, Acclaim WCX-1, and Accucore PFP. The only columns that provided good separation were Acquity HSS T3 Premier and Cogent Bidentate C18, which are grafted with octadecyl (C18) groups, each octadecyl group being linked by at least two attachment points to the silica particles via Si-C bonds.

[0050] The other columns tested did not provide good separation, repeatability, efficiency, asymmetry and / or selectivity.

[0051] Each injected model mixture corresponds to a type of molecule commonly used in petroleum production: two phosphate esters, four amines, and one ammonium compound. Tests on the HSS T3 Premier column yielded the best results and are shown in Figure 3, which is a superposition of the chromatograms obtained for each model mixture.

[0052] These results show that the analytical method of this disclosure provides good separation, repeatability, efficiency, asymmetry and selectivity over a wide range of additives used in petroleum production with different chemical functions.

[0053] The following tests were therefore carried out using Acquity HSS T3 Premier.

[0054] UHPLC

[0055] Equipment: The chromatography system used is a Vanquish UHPLC system from Thermo Fisher Scientific. The column used is an octadecyl-grafted, reverse-phase chromatography column with a trifunctional graft and adsorption protection (Acquity Premier HSS T3), from Waters. It has an internal diameter of 2.1 mm, a length of 150 mm, and is packed with particles 1.8 µm in diameter and with a pore size of 100 Å.

[0056] Mobile phase: Two mobile phases are prepared with water and LC / MS grade methanol. The first, referred to as mobile phase A, consists of a mixture of 95% v / v water and 5% v / v methanol, to which 0.1% v / v formic acid of purity greater than 99% is added. The second, referred to as mobile phase B, consists of a mixture of 5% v / v water and 95% v / v methanol, to which 0.1% v / v formic acid of purity greater than 99% is added.

[0057] Analysis: The column is placed in a thermostatically controlled oven, with a temperature fixed at 35°C throughout the analysis. The mobile phase flow rate is maintained at 0.4 mL / min. The sample injection volume is 5 pL. The sample collection syringe is rinsed before and after injection with a mixture of 10% v / v LC / MS grade water and 90% v / v LC / MS grade methanol for 20 seconds at a flow rate of 10 pL / s.

[0058] Gradient 1: An elution gradient is used (Figure 1a). The method has a total duration of 19 minutes. The gradient begins with 75% of mobile phase B. Between 0 and 2 minutes, the amount of mobile phase B increases linearly from 75% to 80%. Between 2 and 4 minutes, a plateau is reached at 80% of mobile phase B. Between 4 and 9 minutes, the amount of mobile phase B increases linearly from 80% to 90%. Between 9 and 10 minutes, the amount of mobile phase B increases linearly from 90% to 100%. Between 10 and 13 minutes, a plateau is reached at 100% of mobile phase B. Between 13 and 14 minutes, the amount of mobile phase B decreases linearly from 100% to 75%. Between 14 and 19 minutes, a plateau is carried out at 75% of mobile phase B, in order to rebalance the column.

[0059] Gradient 2: An elution gradient is used (Figure 1b). The method has a total duration of 22 minutes. Isocratic elution is performed for 2 minutes with 50% of mobile phase B, then the elution gradient is as follows: Between 2 and 3 minutes, the amount of mobile phase B increases linearly from 50% to 75%. Between 3 and 5 minutes, the amount of mobile phase B increases linearly from 75% to 80%. Between 5 and 7 minutes, a plateau is reached at 80% of mobile phase B. Between 7 and 12 minutes, the amount of mobile phase B increases linearly from 80% to 90%. Between 12 and 13 minutes, the amount of mobile phase B increases linearly from 90% to 100%. Between 13 and 16 minutes, a plateau is maintained at 100% mobile phase B. Between 16 and 17 minutes, the amount of mobile phase B decreases linearly from 100% to 30%. Between 17 and 22 minutes, a plateau is maintained at 50% mobile phase B to re-equilibrate the column.

[0060] Mass spectrometry

[0061] Equipment: The mass spectrometer used is a Thermo Fisher Scientific Exactive Plus. This spectrometer has an Orbitrap analyzer. An electrospray source is used in positive and negative modes for the ionization of compounds. Data acquisition is performed using XCalibur 4.1 software (Thermo Fisher Scientific).

[0062] The column outlet is connected to a 6-way valve that allows switching between two positions: transfer to the mass spectrometer or waste. During the method, the valve is positioned to the waste bin for the first 1.25 minutes and then switches to the mass spectrometer position for the remainder of the analysis. A T-fitting is positioned between the 6-way valve and the source inlet. One outlet of this fitting is directed to the ionization source inlet, while the other is directed to a waste bin. This fitting limits the flow rate of mobile phase reaching the ionization source. Approximately one-third of the flow rate used in chromatography reaches the mass spectrometer, or 0.13 mL / min. The setup is shown schematically in Figure 2.

[0063] The source used is an electrospray source. It can be used in positive or negative mode. In positive mode, the Sheath gas parameter is set to 10, the Aux gas parameter to 20, the Sweep gas parameter to 5, the voltage is fixed at 4.5 kV, and the S-lens parameter is set to 80. In negative mode, the Sheath gas parameter is set to 10, the Aux gas parameter to 5, the Sweep gas parameter to 0, the voltage is fixed at 3.5 kV, and the S-lens parameter is set to 70.

[0064] Example 1: Analysis of production water treated with the commercial anti-corrosion additive A

[0065] 5 pL of a 1000 pg / g solution of anti-corrosion additive A are added to 995 pL of production water, resulting in a final additive concentration of 5 pg / g. The production water contains numerous salts. The calcium content was estimated at approximately 20,000 pg / g, iron at 27 pg / g, potassium at 1800 pg / g, lithium at 110 pg / g, magnesium at 2500 pg / g, and strontium at 4500 pg / g. The pH of this production water is 0.7.

[0066] This boosted production water was analyzed using the previously described method (gradient 1), in positive ionization mode. The chromatograms of ions extracted from the molecules identified in the mixture are shown in Figure 4.

[0067] These chromatograms show the separation and detection of different molecules. Additive A is a complex mixture of numerous molecules. Quaternary ammonium compounds, from the benzalkonium chloride family, can be found with retention times of 2.82 minutes, 4.63 minutes, and 7.45 minutes, for m / z ratios of 304.3000, 332.3311, and 360.3625, respectively. Derivatives of 3-aminopropanoic acid can be found in the Retention times of 2.41 minutes were observed for the m / z ratio 258.2426 and 3.91 minutes for the m / z ratio 286.2741. Hydrolyzed imidazolines were recovered at retention times of 1.94 and 11.21 minutes for m / z ratios of 452.4323 and 359.8503, respectively. All apparent selectivities were greater than 1.18, demonstrating good separation of the aforementioned compounds. Skewness factors ranged from 2 to 5.3, indicating satisfactory peak shapes.

[0068] The separation method presented here allows for the satisfactory detection of different molecules of the anti-corrosion additive A in production water with a high salt content. A 1 pg / g doping test was successfully performed, with equally satisfactory results, demonstrating that the detection limit of this method is less than 1 pg / g, or 1 ppm.

[0069] Another elution gradient (gradient 2) was also used to analyze the mixture. The results obtained are comparable.

[0070] Example 2: Analysis of production water treated with the commercial anti-corrosion additive B

[0071] 5 pL of a 1000 pg / g solution of anti-corrosion additive B are added to 995 pL of production water, resulting in a final additive concentration of 5 pg / g. The production water contains numerous salts. The calcium content was estimated at approximately 18,000 pg / g, iron at 1 pg / g, potassium at 1,500 pg / g, lithium at 100 pg / g, magnesium at 0.5 pg / g, and strontium at 4,600 pg / g. The pH of this production water is 4.

[0072] This boosted production water was analyzed using the method described previously (gradient 1), in negative ionization mode. Ion chromatograms extracted from some of the molecules present in the additive are shown in Figures 4 and 5.

[0073] Additive B is a mixture of phosphoric esters. It contains two distributions of molecules with an increasing number of ethylene oxide motifs: the first comprising molecules with an 8-carbon alkyl chain, the separation of which is shown in Figure 5, and the second comprising molecules with a 10-carbon alkyl chain, the separation of which is shown in Figure 6. The molecules of the first distribution have retention times between 1.5 and 4 minutes, while the molecules of the second distribution have retention times between 3 and 7 minutes.

[0074] The molecules in the distributions are separated according to the length of their alkyl chain (homologous molecules with an 8-carbon alkyl chain are eluted before those with 10 carbons), and also according to the number of ethylene oxide motifs. In this example, the more ethylene oxide motifs a molecule has, the more likely it is to be retained.

[0075] The separation method presented here allows for the satisfactory detection of the anti-corrosion additive B in production water with a high salt content. A 1 pg / g dosing was successfully performed, with equally satisfactory results, demonstrating that the detection limit of this method is less than 1 pg / g, or 1 ppm.

Claims

Demands

1. Method for analyzing additives used in petroleum production using a high-performance liquid chromatography (HPLC) or ultra-high-performance liquid chromatography (UHPLC) process coupled with a high-resolution mass spectrometry (HRMS) process, said method comprising the following steps: a. Injecting into an HPLC or UHPLC column a volume of an aqueous fluid sample comprising at least one additive used in petroleum production, said column containing silica-based particles grafted with octadecyl groups, each octadecyl group being linked by at least two attachment points to the silica particles by Si-C bonds, b. Elute with a mobile phase, and c. Detect the additives by HRMS.

2. Method according to claim 1, characterized in that the additives to be detected are chosen from among anti-corrosion additives, demulsifiers, bactericides, kinetic hydrate inhibitors, mineral deposit inhibitors, anti-foaming additives, and mixtures thereof.

3. Method according to any one of the preceding claims, characterized in that the additives to be detected are chosen from among amines, ammoniums, phosphate esters, oxazolidines, imidazolines, polyethyleneimines, carboxylic acids, sulfates, sulfonates, ethylene or propylene oxides, and mixtures thereof.

4. Method according to any one of the preceding claims, characterized in that the quantity of additives to be detected in the sample is between 0.5 pg / g and 5 mg / g, preferably between 1 pg / g and 100 pg / g.

5. Method according to any one of the preceding claims, characterized in that the aqueous fluid sample is a sample of production water, injection water, or industrial effluents.

6. Method according to the preceding claim characterized in that the production water sample or injection water does not undergo any pretreatment before injection into the HPLC or UHPLC column.

7. Method according to claim 5 or 6 characterized in that the sample comprises a salt content of at least 10g / L.

8. Method according to any one of the preceding claims, characterized in that the size of the silica-based particles is less than 2 pm.

9. Method according to any one of the preceding claims, characterized in that the RP resolving power of the mass spectrometer is at least 10000 FWHM at m / z 200, preferably at least 100000.

10. A method according to any one of the preceding claims, characterized in that the mobile phase comprises - a mobile phase A comprising water and a water-miscible organic solvent, in a ratio between 99:1 and 90:10, and - a mobile phase B comprising water and an alcohol in a ratio between 1:99 and 10:

90.

11. Method according to any one of the preceding claims, characterized in that an elution gradient is used with at least 40% of mobile phase B up to 100% of mobile phase B to return to the initial percentage of mobile phase B.

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