Patent Application
20240294821
The disclosure relates to corrosion inhibition compositions and methods of using such compositions to inhibit corrosion in a sour environment, such as a hydrogen sulfide (H2S)-containing environment of an oil and gas system or component. The compositions and methods can be used in various settings, such as an oil and gas carrying pipeline and/or a component in an oil and gas facility that would handle a sour aqueous fluid.
Hydrogen sulfide and/or carbon dioxide (CO2) in produced oil and gas can cause corrosion in transportation pipelines and oil and gas processing facilities by dissolving in water and corroding metal (e.g., steel).
Existing corrosion inhibitors often do not provide satisfactory performance in sour environments, such as sour environments that contain hydrogen sulfide, and optionally carbon dioxide and/or brine. Additionally, turbulent fluid flow can increase wall sheer stress under high pressure conditions which reduces (e.g., prevents) adhesion of the protective layers formed by corrosion inhibitors in pipelines.
The disclosure relates to corrosion inhibition compositions and methods of using such compositions to inhibit corrosion in a sour environment (e.g., due to the presence of hydrogen sulfide and optionally carbon dioxide). The compositions and methods can be used in various settings, such as an oil and gas carrying pipeline (e.g., a production pipeline, a transportation pipeline) and/or a component in an oil and gas facility that would handle a sour aqueous fluid (e.g., a crude producing facility, a crude processing facility, a gas oil separation plant). The compositions include a 2-substituted benzothiazole, a cationic surfactant, an ammonium salt, a glycol and a solvent that can include water.
The compositions and methods can provide improved corrosion inhibition performance in sour environments relative to certain other corrosion inhibitors. The compositions can reduce (e.g., prevent) pipeline leaks, pipeline bursting, preventative maintenance, turnaround maintenance, and/or losses in production as well as financial costs associated with these events. Without wishing to be bound by theory, it is believed that the compositions can form a protective film on a metal surface to provide protection from corrosion. The compositions and methods provide improved corrosion inhibiting films relative to certain other corrosion inhibitors (see discussion below).
The compositions and methods can be relatively inexpensive to produce and/or implement. The compositions can be used at relatively low concentrations and/or volumes relative to certain other corrosion inhibitors. The corrosion inhibitors can exhibit stability over a period of several months and greater stability relative to certain other corrosion inhibitor compositions. The compositions and methods are less toxic than certain other corrosion inhibition compositions. Thus, water pollution can be reduced relative to the use of certain other corrosion inhibition compositions.
In a first aspect, the disclosure provides a composition, including a 2-substituted benzothiazole of formula:
where R is C1-18 alkyl, —SH, —NH2, —NH-phenyl, —OH, —C(O)H, —Si(CH3)3, —CO2H, or —C1-6 alkyl-OH; a cationic surfactant of formula:
where n=12, 14, 16 or 18; an ammonium salt; a glycol; and a solvent that includes water.
In some embodiments, the composition includes 1-15 wt. % of the 2-substituted benzothiazole, 1-10 wt. % of the cationic surfactant, 1-5 wt. % of the ammonium salt, 1-50% of the glycol, and 1-50% of the solvent.
In some embodiments, the composition includes 1-9 wt. % of the 2-substituted benzothiazole, 1-5 wt. % of the cationic surfactant, 1-5 wt. % of the ammonium salt, 1-50% of the glycol, and 1-50% of the solvent.
In some embodiments, the composition includes 7-9 wt. % of the 2-substituted benzothiazole, 3-5 wt. % of the cationic surfactant, 1-3 wt. % of the ammonium salt, 40-50% of the glycol, and 40-50% of the solvent.
In some embodiments, the 2-substituted benzothiazole includes 2-mercaptobenzothiazole.
In some embodiments, the cationic surfactant includes benzyl dodecyl dimethylammonium chloride.
In some embodiments, the ammonium salt includes an ammonium halide, ammonium thiocaytanate, ammonium carbonate, and/or ammonium sulphate.
In some embodiments, the glycol includes ethylene glycol, propylene glycol, propyl ether, dipropylene glycol dimethyl ether, and/or ethylene glycol diethyl ether.
In some embodiments, a ratio of the 2-substituted benzothiazole to cationic surfactant to ammonium salt by weight is 4:2:1.
In some embodiments, the 2-substituted benzothiazole includes 2-mercaptobenzothiazole, the cationic surfactant includes benzyl dodecyl dimethylammonium chloride, and the ammonium salt includes ammonium iodide.
In some embodiments, the composition includes 8.5 wt. % 2-mercaptobenzothiazole, 4.3 wt. % benzyl dodecyl dimethylammonium chloride, 2.2 w.t % ammonium iodide, 42.5 wt. % ethylene glycol, and 42.5 wt. % water.
In a second aspect, the disclosure provides a method, including disposing a composition of the disclosure into a first liquid including hydrogen sulfide, thereby forming a second liquid, and contacting the second liquid with a member selected from the group consisting of an oil and gas carrying pipeline, a crude producing facility, and a crude processing facility, thereby inhibition corrosion of the member.
In certain embodiments, the first liquid further includes carbon dioxide.
In certain embodiments, a ratio of hydrogen sulfide to carbon dioxide in the first liquid is at least 1:200.
In certain embodiments, the member includes steel.
In certain embodiments, the composition is present in the second liquid at a concentration of 5 ppm to 100 ppm.
In certain embodiments, the composition includes 1-15 wt. % of the 2-substituted benzothiazole, 1-10 wt. % of the cationic surfactant, 1-5 wt. % of the ammonium salt, 1-50% of the glycol, and 1-50% of the solvent.
In certain embodiments, a ratio of the 2-substituted benzothiazole to cationic surfactant to ammonium salt by weight is 4:2:1.
In certain embodiments, the 2-substituted benzothiazole includes 2-mercaptobenzothiazole, the cationic surfactant includes benzyl dodecyl dimethylammonium chloride, and the ammonium salt includes ammonium iodide.
In certain embodiments, the composition includes 8.5 wt. % 2-mercaptobenzothiazole, 4.3 wt. % benzyl dodecyl dimethylammonium chloride, 2.2 w.t % ammonium iodide, 42.5 wt. % ethylene glycol, and 42.5 wt. % water.
The disclosure provides a composition that includes a 2-substituted benzothiazole, a cationic surfactant, an ammonium salt, a glycol and a solvent. The compositions can be used to reduce (e.g., eliminate) corrosion in settings such as, an oil and gas carrying pipeline and/or a component in an oil and gas facility that would handle a sour aqueous fluid (see discussion below).
The 2-substituted benzothiazole has the formula:
where R is C1-18 alkyl (e.g., C1-6 alkyl, C1-5 alkyl, methyl, ethyl, n-propyl, isopropyl, butyl, pentyl), —SH, —NH2, —NH-phenyl, —OH, —C(O)H, —Si(CH3)3, —CO2H, or —C1-6 alkyl-OH. Examples of the 2-substituted benzothiazole include 2-mercaptobenzothiazole, 2-methylbenzothiazole, 2-ethylbenzothiazole, 2-propylbenzothiazole, 2-isopropylbenzothiazole, 2-butylbenzothiazole, 2-pentylbenzothiazole, 2-methylbenzothiazole 2-aminobenzothiazole, 2-N-phenylaminobenzothiazole, 2-hydroxylbenzothiazole, 2-formylbenzothiazole, 2-trimethylsilylbenzothiazole, 2-carboxybenzothiazole, 2-(hydroxymethyl)benzothiazole, and 2,2′-dithiobis(benzothiazole).
The cationic surfactant has the formula:
where n=12, 14, 16, or 18.
Examples of the ammonium salt include an ammonium halide (e.g., ammonium chloride, ammonium bromide, ammonium iodine), ammonium thiocaytanate, ammonium carbonate, and ammonium sulphate. In certain embodiments, the ammonium halide includes ammonium iodine. Without wishing to be bound by theory, it is believed that the ammonium salt serves as an intensifier. The intensifier increases the bonding of the 2-substituted benzothiazole and the cationic surfactant onto the metal (e.g., steel) surface through electrostatic (Van der Waals) interactions (see discussion below).
Examples of the glycol include ethylene glycol, propylene glycol, propyl ether, dipropylene glycol dimethyl ether, and ethylene glycol diethyl ether. Without wishing to be bound by theory, it is believed that the glycol servers as a stabilizer. The stabilizer increases the dissolution and/or stability of the 2-substituted benzothiazole and/or the cationic surfactant in solution.
In certain embodiments, the 2-substituted benzothiazole is 2-mercaptobenzothiazole.
In certain embodiments, the cationic surfactant is benzyl dodecyl dimethylammonium chloride.
In certain embodiments, the 2-substituted benzothiazole is 2-mercaptobenzothiazole and the cationic surfactant is benzyl dodecyl dimethylammonium chloride.
In certain embodiments, the 2-substituted benzothiazole is 2-mercaptobenzothiazole, the cationic surfactant is benzyl dodecyl dimethylammonium chloride, and the ammonium salt is ammonium iodide. In certain embodiments, the 2-substituted benzothiazole is 2-mercaptobenzothiazole, the cationic surfactant is benzyl dodecyl dimethylammonium chloride, the ammonium salt is ammonium iodide, and the glycol is ethylene glycol.
In some embodiments, the composition includes at least 1 (e.g., at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9, at least 10, at least 11, at least 12, at least 13, at least 14) wt. % and/or at most 15 (e.g., at most 14, at most 13, at most 12, at most 11, at most 10, at most 9, at most 8, at most 7, at most 6, at most 5, at most 4, at most 3, at most 2) wt. % of the 2-substituted benzothiazole (e.g., 2-mercaptobenzothiazole).
In some embodiments, the composition includes at least 1 (e.g., at least 2, at least 3, at least 4, at least 5, at least 6, at least 7, at least 8, at least 9) wt. % and/or at most 10 (e.g., at most 9, at most 8, at most 7, at most 6, at most 5, at most 4, at most 3, at most 2) wt. % of the cationic surfactant (e.g., benzyl dodecyl dimethylammonium chloride).
In some embodiments, the composition includes at least 1 (e.g., at least 2, at least 3, at least 4) wt. % and/or at most 5 (e.g., at most 4, at most 3, at most 2) wt. % of the ammonium salt (e.g., ammonium iodine).
In some embodiments, the composition includes at least 1 (e.g., at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45) wt. % and/or at most 50 (e.g., at most 45, at most 40, at most 35, at most 30, at most 25, at most 20, at most 15, at most 10, at most 5) wt. % of the glycol (e.g., ethylene glycol).
In some embodiments, the composition includes at least 1 (e.g., at least 5, at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45) wt. % and/or at most 50 (e.g., at most 45, at most 40, at most 35, at most 30, at most 25, at most 20, at most 15, at most 10, at most 5) wt. % of the solvent.
In certain embodiments, a ratio of the 2-substituted benzothiazole to the cationic surfactant by weight is at least 1:10 (e.g., at least 1:9, at least 1:8, at least 1:7, at least 1:6, at least 1:5, at least 1:4, at least 1:3, at least 1:2, at least 1:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least 9:1, at least 10:1, at least 11:1, at least 12:1, at least 13:1, at least 14:1) and/or at most 15:1 (e.g., at most 14:1, at most 13:1, at most 12:1, at most 11:1, at most 10:1, at most 9:1, at most 8:1, at most 7:1, at most 6:1, at most 5:1, at most 4:1, at most 3:1, at most 2:1, at most 1:1, at most 1:2, at most 1:3, at most 1:4, at most 1:5, at most 1:6, at most 1:7, at most 1:8, at most 1:9).
In certain embodiments, a ratio of the 2-substituted benzothiazole to the ammonium salt by weight is at least 1:5 (e.g., at least 1:4, at least 1:3, at least 1:2, at least 1:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least 9:1, at least 10:1, at least 11:1, at least 12:1, at least 13:1, at least 14:1) and/or at most 15:1 (e.g., at most 14:1, at most 13:1, at most 12:1, at most 11:1, at most 10:1, at most 9:1, at most 8:1, at most 7:1, at most 6:1, at most 5:1, at most 4:1, at most 3:1, at most 2:1, at most 1:1, at most 1:2, at most 1:3, at most 1:4).
In certain embodiments, a ratio of the cationic surfactant to the ammonium salt by weight is at least 1:5 (e.g., at least 1:4, at least 1:3, at least 1:2, at least 1:1, at least 2:1, at least 3:1, at least 4:1, at least 5:1, at least 6:1, at least 7:1, at least 8:1, at least 9:1) and/or at most 10:1 (e.g., at most 9:1, at most 8:1, at most 7:1, at most 6:1, at most 5:1, at most 4:1, at most 3:1, at most 2:1, at most 1:1, at most 1:2, at most 1:3, at most 1:4).
In certain embodiments, the ratio of the 2-substituted benzothiazole to the cationic surfactant by weight is 4:2. In certain embodiments, the ratio of the 2-substituted benzothiazole to the ammonium salt by weight is 4:1. In certain embodiments, the ratio of the cationic surfactant to the ammonium salt by weight is 2:1. In certain embodiments, the ratio of the 2-substituted benzothiazole to cationic surfactant to ammonium salt by weight is 4:2:1. Without wishing to be bound by theory, it is believed that a ratio of the ratio of the 2-substituted benzothiazole to cationic surfactant to ammonium salt (e.g., 2-mercaptobenzothiazole to benzyl dodecyl dimethylammonium chloride to ammonium iodide) by weight of 4:2:1 can provide improved corrosion inhibition and/or increased stability in solution relative to certain other formulations that include different ratios and/or constituents.
In some embodiments, the composition includes 8.5 wt. % of the 2-substituted benzothiazole, 4.3 wt. % of the cationic surfactant, 2.2 w.t % of the ammonium salt, 42.5 wt. % of the glycol, and 42.5 wt. % of the solvent. In some embodiments, the composition includes 8.5 wt. % 2-mercaptobenzothiazole, 4.3 wt. % benzyl dodecyl dimethylammonium chloride, 2.2 wt. % ammonium iodide, 42.5 wt. % ethylene glycol, and 42.5 wt. % water.
Without wishing to be bound by theory, it is believed that sour corrosion has a mechanism distinct from certain other forms of corrosion. Hydrogen sulfide gas can dissolve in an aqueous solution according to reaction (1)
H2S(g)↔H2S(aq) (1)
Aqueous hydrogen sulfide can directly dissociate after dissolving to form bisulfide (HS−) and/or sulfide (S2−) species as shown in reactions (2) and (3), respectively. Hydrogen sulfide can also act as a source of hydrogen ions.
H2S(aq)↔H(aq)++HS(aq)− (2)
HS(aq)−+H(aq)++S(aq)2− (3)
Hydrogen sulfide can also undergo a reduction, as shown in reaction (4)
2H2S(aq)+2e−↔H2(g)+2HS(aq)− (4)
The overall reaction with iron in steel in a sour environment can be written as
Fe(s)+H2S(aq)↔FeS(s)+H2(g) (5)
Thus, in sour corrosion, FeS can form rather than, or in addition to, the iron undergoing oxidation. Without wishing to be bound by theory, it is believed that depending on the conditions, one or more types of FeS can be formed (e.g., troilite, cubic FeS, and mackinawite). Two different layers are believed to be present: a porous and thick outer layer (mackinawite), and a thin and dense inner layer (cubic FeS).
Without wishing to be bound by theory, it is believed that one or more species in the compositions can interact with the surface (e.g., metal-containing surface, such as steel) to be protected to form a protective film on a metal surface by chemisorption and/or physisorption to provide protection from corrosion. This film formation reduces (e.g., prevents) access of hydrogen sulfide to the metal surface, thereby reducing (e.g., preventing) the occurrence of the reaction shown in equation (5) and the formation of FeS.
Without wishing to be bound by theory, it is believed that the 2-substituted benzothiazoles have a relatively high inhibition efficiency due to relatively strong film formation. The R groups of the 2-substituted benzothiazoles (e.g., alkyl, —SH, —NH2) include electron rich atoms that can donate excess electrons to the metal (e.g., steel) surface to allow for relatively strong bonding of the film to the surface (chemisorption).
Without wishing to be bound by theory, it is believed that the cationic surfactant can have an electrostatic interaction with HS− (produced in reaction (2)) to form an electrostatic bond on the metal (e.g., steel) surface (physisorption), thereby protecting the metal surface from corrosion due to HS−.
The compositions can be used to reduce (e.g., prevent) corrosion of a metal due to a sour environment (e.g., due to the presence of hydrogen sulfide and optionally carbon dioxide). The compositions can be used to reduce (e.g., prevent) corrosion in an aqueous fluid that contains hydrogen sulfide and optionally carbon dioxide, such as an aqueous fluid in an oil and gas carrying pipeline (e.g., a production pipeline, a transportation pipeline) and/or a component in an oil and gas facility that would handle a sour aqueous fluid (e.g., a crude producing facility, a crude processing facility, a gas oil separation plant). Hydrogen sulfide can be present in a producing formation and/or from a surface source, such as injection water. In some embodiments, the aqueous fluid contains a brine that include chlorides.
The compositions can inhibit corrosion in a component, sub-system or system made of a metal-containing material, such as steel (e.g., carbon steel, stainless steel). Typically, the components, sub-systems and systems disclosed in the preceding paragraph are made of such materials.
Without wishing to be bound by theory, it is believed that sour environments can provide relatively aggressive corrosion environments for certain metals (e.g., steel), particularly under relatively high hydrogen sulfide to carbon dioxide ratios, where FeS corrosion products dominate. Pitting mechanisms are also expected to occur. In certain embodiments, the hydrogen sulfide to carbon dioxide ratio in the aqueous fluid being treated is at least 1:200 (e.g., at least 1:150, at least 1:100, at least 1:50).
In general, the compositions can be used at any appropriate concentration. In some embodiments, the corrosion inhibitor is used at a concentration of at least 5 (e.g., at least 10, at least 15, at least 20, at least 25, at least 30, at least 35, at least 40, at least 45, at least 50, at least 55, at least 60, at least 65, at least 70, at least 75, at least 80, at least 85, at least 90, at least 95) ppm and/or at most 100 (e.g., at most 95, at most 90, at most 85, at most 80, at most 75, at most 70, at most 65, at most 60, at most 55, at most 50, at most 45, at most 40, at most 35, at most 30, at most 25, at most 20, at most 15, at least 10) ppm.
The corrosion rate can calculated using a weight loss as shown in equation (1)
where ΔW is the weight loss in mg, p is the density the sample, A is an area of the exposed sample, and T is the exposure time. In some embodiments, for a standard mild steel coupon (C-1018) with a density of 7.89 g/cm3, an exposed area of 7.86 square inches and an exposure time of one day, the corrosion rate is at least 2.87 (e.g., at least 3, at least 3.5, at least 4, at least 4.5) mils per year (mpy) and/or at most 5 (e.g., at most 4.5, at most 4, at most 3.5, at most 3) mpy.
The corrosion inhibition efficiency can be calculated using equation (2)
where CRblank and CRinhibitor are the corrosion rate, as calculated by equation (1), in the absence and presence of a corrosion inhibitor, respectively. In some embodiments, the corrosion inhibition efficiency is at least 73 (e.g., at least 75, at least 80, at least 85, at least 90, at least 95, at least 98) % and/or at most 98.8 (e.g., at most 98.5, at most 98, at most 95, at most 90, at most 85, at most 80, at most 75) %.
Composition 1 was prepared by dissolving 8.5 wt. % of 2-mercaptobenzothiazole, 4.3 wt. % of benzyl dodecyl dimethylammonium chloride, and 2.2 wt. % of ammonium iodide into a 85 wt. % glycol-water mixture in a graduated glass bottle. The resulting solution was heated to a temperature of 50° C. on a hot plate for 24 hours to ensure complete dissolution and stability of the mixture. The composition of Composition 1 is shown in Table 1. All reagents were obtained from Sigma Aldrich.
Composition 1 was observed to be stable after several months of storage, by observing for uniformity. Other corrosion inhibition compositions prepared were not stable in solution after 2 months so were not evaluated further.
Linear polarization resistance (LPR) was used to test the corrosion inhibition performance of Composition 1. LPR was measured using a Gamry 1010E Potentiostat/Galvanostat (Gamry Inc., USA). The LPR of a C1018 carbon steel coupon was measured in 3.5% NaCl in saturated carbon dioxide in the presence of hydrogen sulfide at 55° C. The gas composition is shown in Table 3. The solution was continuously stirred using a magnetic stirrer set at 500 rpm throughout the test. After 2 hours of purging, the test coupon was immersed into the corrosion cell and open circuit potential (OCP) was measured for 1 h to ensure the stability of the potential with time. Corrosion rate logging using linear polarization resistance (LPR) was initiated and the corrosion rate was recorded automatically every 10 minutes. The test was then left for a further 44 h. The corrosion rate was measured for four hours without the addition of corrosion inhibitor, followed by two sequential additions of 5 ppm of composition 1 after 4 hours and 22 hours.
The results indicate that 5 ppm is a sufficient dosage to inhibit corrosion below an acceptable industrial corrosion rate in the oil and gas sector (5 mpy).
Potentiodynamic polarization (PDP) was used to test the corrosion inhibition performance of Composition 1. Potentiodynamic polarization (Tafel) plots were obtained to investigate the anodic and cathodic electrochemical processes that occur on the C1018 carbon steel surface during the corrosion and the corrosion inhibition processes. Using the methods of Example 2, concentrations of Composition 1 of 10, 25, 50 and 100 ppm were used for potentiodynamic polarization (PDP) experiments. The PDP curves were measured with potentials from −250 to +250 mV vs. SCE using a 0.5 mV/s scan rate.
Inhibition efficiency (IE %) values were calculated from the electrochemical measurements using equations 3 and 4.
where Rp(blank) and Rp(inh) are the polarization resistance recorded in the absence and presence of Composition 1, respectively.
where icorr(blank) and icorr(inh) are the corrosion current density recorded in the absence and presence of Composition 1, respectively.
The performance of Composition 1 was evaluated and compared with commercial corrosion inhibitor using a high temperature and high-pressure (HTHP) autoclave rotating cage to simulate field environments. The commercial corrosion inhibitor included an alkyl benzyl pyridinium salt and imidazoline derivative.
A HTHP autoclave rotating cage was used to conduct the corrosion tests under simulated and controlled dynamic field conditions. A four-liter reactor was constructed from C-276 alloy, allowing it to withstand harsh corrosive environments. The test material was carbon steel coupons (1018) and the coupons were cleaned and degreased before and after testing following the ASTM G1 “Practice for preparing, cleaning and evaluating corrosion test specimen procedure”. The coupons were positioned in a fixed cage made out of PEEK material and then mounted in the autoclave.
The autoclave was purged with N2 to remove dissolved oxygen. The autoclave was then pressurized with hydrogen sulfide and carbon dioxide. The autoclave was heated to the required test temperature of 182° F. The detailed experimental conditions and parameters are presented in Table 3.
A kerosene:water (1:1) mixture was stirred at room temperature with 10 ppm of corrosion inhibitor sample (Composition 1 or commercial corrosion inhibitor) in the autoclave. After 2 hours, the kerosene was removed and the remaining water was used in the autoclave for the final test. The final pressure was maintained at the required pressure (250 psi) using high purity nitrogen gas. In all tests, the corrosion inhibitor formulations were injected immediately after fixing the coupons in the autoclave. The corrosion rate and inhibition efficiency of the samples were calculated using a weight loss and equations (1) and (2) (see discussion above). The density of the standard mild steel coupon (C-1018) was 7.89 g/cm3, the area of the exposed coupon was 7.86 square inches and the exposure time was one day.
The corrosion rate and corrosion inhibition efficiency of the commercial corrosion inhibitor and Composition 1 are shown in
Before cleaning, the coupon tested with commercial corrosion inhibitor (
While certain embodiments have been disclosed above, the disclosure is not limited to such embodiments.
In some embodiments, the compositions can inhibit corrosion in a sweet environment, such as a carbon dioxide containing environment. In some embodiments, the compositions of the disclosure can inhibit corrosion due to the presence of an organic acid and/or a brine. In some embodiments, the brine contains chloride.
In certain embodiments, the 2-substituted benzothiazole includes one or more additional substituents, such as a halogen (e.g., chlorine) group. In certain embodiments, the 2-substituted benzothiazole is 2-(hydroxymethyl)benzothiazole.
