An organic acid salt protective fluid for the annular space of oil and gas wells, and its preparation method and application

Abstract

The present invention belongs to the field of petroleum extraction technology, and specifically relates to an organic acid salt protective fluid for the annulus of oil and gas wells, its preparation method, and application. The preparation method is as follows: disodium lauryl iminodipropionate, (3-chloro-2-hydroxypropyl) dodecyldimethylammonium chloride, and an organic solvent are added to a four-necked flask equipped with a condenser, stirred evenly, adjusted to a pH of 8-9, and heated under reflux; the intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized and dried to obtain a protective fluid main agent; the protective fluid main agent, sodium formate, hydroxyethylidene diphosphonic acid, and water are added to a reaction vessel, stirred evenly, and the product organic acid salt protective fluid is obtained. The organic acid salt protective fluid of the present invention has the advantages of good corrosion and scale inhibition effects and high sterilization efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to an organic acid salt protective fluid for the annular space of an oil and gas well, and a preparation method and application thereof. Background Art

[0002] In the field of oil and gas well annulus protection fluid, also known as packer fluid, plays a crucial role. Filled between the tubing and reservoir casing, it has two primary functions: first, corrosion resistance, which protects the tubing, casing, and downhole tools (such as packers and downhole safety valves) from corrosion; and second, pressure balancing. The packer fluid, with a certain density, balances formation pressure, tubing pressure, and casing pressure, thereby protecting the tubing, casing, and packers.

[0003] For producing wells, annular fluids will not flow unless the well is repaired. For non-producing wells, they will not flow unless the well is put into production. Therefore, the annular fluid often remains in the casing for extended periods, sometimes even for years. Under the specific downhole temperature and pressure, the fluid must remain stable over time, preventing solid precipitation. During repairs or production, the fluid must not damage the reservoir and must provide strong protection against the oil and gas formations while maintaining excellent corrosion resistance.

[0004] To balance formation pressure, tubing pressure, and casing pressure, the annular protection fluid requires a certain density. Currently, the most commonly used weighting agent is formate. To prevent corrosion and scaling, various chemical additives, such as corrosion inhibitors, biocides, and scale inhibitors, are often added. The selection and proportioning of these additives are crucial to the overall performance of the annular protection fluid.

[0005] CN1199430A discloses a high-water content, low-viscosity, oil-continuous phase microemulsion and emulsion and their use in cleaning applications. The excellent high-water content, oil-continuous phase microemulsion and emulsion for cleaning contain defined amounts of water, one or more anionic surfactants derived from carboxylates of selected molecular weights, and one or more organic solvents, resulting in compositions with low conductivity and low viscosity. The microemulsion contains nitrite, which has strong oxidizing properties and can exacerbate corrosion if the amount used is not properly controlled.

[0006] CN107325803B discloses an annular protection fluid for nitrogen injection wells that can inhibit oxygen corrosion and its preparation method, belonging to the technical field of oil and gas well corrosion protection. A nitrogen injection well annular protection fluid system is formulated using a corrosion inhibitor, a bactericide, a pH regulator, a deoxidizer, a density regulator, and a scale inhibitor. The annular protection fluid comprises the following components, calculated by mass percentage: 10-12% imidazoline corrosion inhibitor, 0.5-2.5% isothiazolinone bactericide, 3-5% alkanolamine pH regulator, 6-8% deoxidizer formulated from a sulfite and oxime mixture, 10-20% organic acid salt density regulator, 0.5-1.5% organic phosphonic acid scale inhibitor, and the balance is water. If necessary, an appropriate amount of an anti-swelling agent may also be added. The annular protection fluid provided by this invention can effectively control the oxygen corrosion problem faced by the annulus of nitrogen injection wells, while also having the advantages of minimal damage to the reservoir, strong stability, and environmental friendliness. However, the addition of sulfite as a scavenger in this formula can easily cause the growth of sulfate-reducing bacteria, further aggravating bacterial corrosion. Summary of the Invention

[0007] The present invention addresses the deficiencies of the prior art and provides an organic acid salt protective fluid for annular spaces of oil and gas wells, and its preparation method and application. The organic acid salt protective fluid of the present invention has the advantages of good corrosion and scale inhibition effects and high sterilization efficiency.

[0008] One of the purposes of the present invention is to disclose an organic acid salt protective fluid for the annulus of an oil and gas well. The composition and mass components of the protective fluid are as follows:

[0009] 1 part of protective liquid main agent;

[0010] 0.5-1 part of sodium formate;

[0011] 0.1-0.3 parts of hydroxyethylidene diphosphonic acid;

[0012] 87.7-88.4 parts of water.

[0013] The molecular structure of the protective liquid main agent is as follows:

[0014] .

[0015] Another object of the present invention is to disclose a method for preparing the organic acid salt protective solution, the specific steps of which are as follows:

[0016] (1) Add disodium lauryl iminodipropionate, (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and an organic solvent to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux;

[0017] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is then recrystallized and dried to obtain the main agent of the protective solution;

[0018] (3) Add the protective solution main agent, sodium formate, hydroxyethylidene diphosphonic acid, and water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0019] In the present invention, preferably, based on 1 mole part of disodium lauryl iminodipropionate, the amount of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride is 0.8-1.2 mole parts; more preferably, based on 1 mole part of disodium lauryl iminodipropionate, the amount of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride is 0.9-1.1 mole parts.

[0020] In the present invention, preferably, the organic solvent in step (1) is one of methanol, ethanol, propanol, isopropanol, butanol, and isobutanol, and the mass ratio of the organic solvent to disodium lauryl iminodipropionate is 10-30:1.

[0021] More preferably, the organic solvent is one of ethanol or isobutanol.

[0022] In the present invention, preferably, the reflux time in step (1) is 24-72 hours.

[0023] In the present invention, preferably, the solvent for recrystallization in step (2) is one of ethyl acetate or cyclohexane.

[0024] The equation for the synthesis reaction of the main agent of the organic acid salt protective solution of the present invention is as follows:

[0025]

[0026] .

[0027] The third object of the present invention is to disclose the application of the organic acid salt protective fluid in the protection of oil casing in oil and water wells.

[0028] The organic acid salt protective fluid of the present invention comprises a main agent molecule containing a diquaternary ammonium salt, which carries a positive charge and can be adsorbed on a metal surface, preventing hydrogen ions from approaching the metal surface and hindering electrons in the metal from being captured by hydrogen ions, thereby protecting the metal from acid corrosion and having a sterilizing effect. The main agent molecule comprises a carboxylic acid group, which forms a chelate film on the metal surface to protect the metal. The main agent molecule, dodecyl, has a hydrophobic effect and can form a hydrophobic barrier on the metal surface, preventing corrosive liquid from approaching the metal, thereby further enhancing the corrosion inhibition effect. Sodium formate is a typical weighting agent for the environmental control protective fluid and can increase the density of the annular space protective fluid, thereby better balancing the formation pressure, the oil pipe pressure and the casing pressure. Hydroxyethylidene diphosphonic acid is a typical scale inhibitor and can prevent scale from growing on the metal surface, causing crystal distortion and thus inhibiting scale.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The organic acid salt protective solution of the present invention is simple to prepare and easy to use, and has the three-in-one functions of corrosion inhibition, sterilization, and scale inhibition;

[0031] (2) The organic acid salt protective solution of the present invention has a good corrosion inhibition effect, and the corrosion inhibition rate reaches more than 92%;

[0032] (3) The organic acid salt protective solution of the present invention has a good bactericidal effect, with a bactericidal rate of 100%;

[0033] (4) The organic acid salt protective liquid of the present invention has a good scale inhibition effect, and the scale prevention rate reaches more than 97%. DETAILED DESCRIPTION

[0034] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0035] Example 1

[0036] (1) Add 50 mmol of disodium lauryl iminodipropionate, 40 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 187 g of isopropanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 24 h.

[0037] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0038] (3) Add 10 g of the protective solution main agent, 5 g of sodium formate, 1 g of hydroxyethylidene diphosphonic acid, and 884 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0039] Example 2

[0040] (1) Add 50 mmol of disodium lauryl iminodipropionate, 60 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 200 g of ethanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 32 h.

[0041] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0042] (3) Add 10 g of the protective solution main agent, 6 g of sodium formate, 2 g of hydroxyethylidene diphosphonic acid, and 882 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0043] Example 3

[0044] (1) Add 50 mmol of disodium lauryl iminodipropionate, 42 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 280 g of propanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 24 h.

[0045] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0046] (3) Add 10 g of the protective solution main agent, 7 g of sodium formate, 2 g of hydroxyethylidene diphosphonic acid, and 881 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0047] Example 4

[0048] (1) Add 50 mmol of disodium lauryl iminodipropionate, 45 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 300 g of butanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 48 h.

[0049] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0050] (3) Add 10 g of protective solution main agent, 10 g of sodium formate, 1 g of hydroxyethylidene diphosphonic acid, and 879 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0051] Example 5

[0052] (1) Add 50 mmol of disodium lauryl iminodipropionate, 48 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 402 g of propanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 48 h.

[0053] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0054] (3) Add 10 g of the protective solution main agent, 10 g of sodium formate, 3 g of hydroxyethylidene diphosphonic acid, and 877 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0055] Example 6

[0056] (1) Add 50 mmol of disodium lauryl iminodipropionate, 55 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 500 g of ethanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 60 h.

[0057] (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is recrystallized from ethyl acetate and dried to obtain the main agent of the protective solution;

[0058] (3) Add 10 g of the protective solution main agent, 9 g of sodium formate, 2 g of hydroxyethylidene diphosphonic acid, and 879 g of water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0059] Example 7

[0060] (1) Add 50 mmol of disodium lauryl iminodipropionate, 52 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 560 g of isobutanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 72 h.

[0061] (2) The intermediate product is subjected to vacuum distillation to obtain a viscous solid, which is recrystallized from cyclohexane and dried to obtain the main agent of the protective solution;

[0062] (3) Add 10 g of the protective solution main agent, 8 g of sodium formate, 3 g of hydroxyethylidene diphosphonic acid, and 879 g of water into a reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0063] Example 8

[0064] (1) Add 50 mmol of disodium lauryl iminodipropionate, 51 mmol of (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and 464 g of ethanol to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux for 72 h.

[0065] (2) The intermediate product is subjected to vacuum distillation to obtain a viscous solid, which is recrystallized from cyclohexane and dried to obtain the main agent of the protective solution;

[0066] (3) Add 10 g of the protective solution main agent, 8 g of sodium formate, 3 g of hydroxyethylidene diphosphonic acid, and 879 g of water into a reaction vessel and stir evenly to obtain the product organic acid salt protective solution.

[0067] Example 9 Corrosion rate test experiment

[0068] 950 ml of produced water from an oil field in a certain block was taken, 250 ml of the organic acid salt protective solution (Examples 1-8) of the present invention was added, and the static corrosion rate at normal pressure was measured at 90°C using a Q235 coupon, and the corrosion inhibition rate was calculated. The test method was based on method 4.7 of SY / T5273-2014 "Performance Indicators and Evaluation Methods for Corrosion Inhibitors for Oilfield Produced Water Treatment". At the same time, produced water was used as a blank comparison. The initial corrosion rate of the produced water was 0.265 mm / a, and the test period was 7 days. The test results are shown in Table 1.

[0069] It can be seen from Table 1 that the corrosion inhibition rates of the organic acid salt protective solutions of the present invention (Examples 1-8) all reached above 92%, with the highest reaching 95%. The organic acid salt protective solutions of the present invention have good anti-corrosion effects.

[0070] Example 10 Evaluation of Sterilization Effect

[0071] 99 ml of produced water from a certain oil field was added to a series of narrow-necked bottles, and 1 ml of the present invention was added. The mixture was shaken and placed in a 60°C oven. Samples were taken after 1 hour, and the sulfate-reducing bacteria content was detected using the three-tube MPN method. The sterilization rate was calculated, and the produced water was used as a blank for comparison. The initial sulfate-reducing bacteria content in the produced water was 450 cells / ml. The test results are shown in Table 1.

[0072] As can be seen from Table 1, the organic acid salt protective solutions of the present invention (Examples 1-8) all have good bactericidal effects, with a bactericidal rate of 100%. Therefore, no bactericide is required to be added to the annular organic acid salt protective solution.

[0073] Example 11 Evaluation of scale inhibition effect

[0074] The anti-scaling rate of CaCO3 was tested with reference to the method in SY / T5673-2020 "General Technical Conditions for Anti-scaling Agents for Oilfields", where the concentration of the solution in 8.16 was changed to 10wt%. The test results are shown in Table 1.

[0075] Table 1 Test results of corrosion inhibition, scale prevention and sterilization

[0076] sample Corrosion inhibition rate, % Sterilization rate, % Anti-scaling rate, % Example 1 92.1 100 97.1 Example 2 93.4 100 97.5 Example 3 94.5 100 98 Example 4 94.2 100 98.3 Example 5 95.0 100 98.5 Example 6 94.8 100 98.5 Example 7 95 100 98.8 Example 8 95.1 100 98.6

[0077] It can be seen from Table 1 that the scale inhibition rates of the organic acid salt protective solutions of the present invention (Examples 1-8) all reached over 97%, with the highest reaching 98.8%. The organic acid salt protective solutions of the present invention have good scale inhibition effects.

[0078] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. An organic acid salt protective fluid for the annulus of an oil and gas well, characterized in that: The composition and mass components of the protective liquid are as follows: 1 part of protective liquid main agent; 0.5-1 part of sodium formate; 0.1-0.3 parts of hydroxyethylidene diphosphonic acid; Water 87.7-88.4 parts; The molecular structure of the protective liquid main agent is as follows: 。 2. The method for preparing an organic acid salt protective fluid for annular space of an oil and gas well according to claim 1, characterized in that: The preparation method is as follows: (1) Add disodium lauryl iminodipropionate, (3-chloro-2-hydroxypropyl) dodecyl dimethyl ammonium chloride, and an organic solvent to a four-necked flask equipped with a condenser, stir evenly, adjust the pH to 8-9, and heat under reflux; (2) The intermediate product is subjected to reduced pressure distillation to obtain a viscous solid, which is then recrystallized and dried to obtain the main agent of the protective solution; (3) Add the protective solution main agent, sodium formate, hydroxyethylidene diphosphonic acid, and water into the reaction vessel and stir evenly to obtain the product organic acid salt protective solution; Based on 1 mole part of disodium lauriiminodipropionate, the amount of (3-chloro-2-hydroxypropyl)dodecyldimethylammonium chloride used is 0.8-1.2 mole parts.

3. The preparation method according to claim 2, characterized in that Based on 1 mole of disodium lauriiminodipropionate, the amount of (3-chloro-2-hydroxypropyl)dodecyldimethylammonium chloride used is 0.9-1.1 mole parts.

4. The preparation method according to claim 2, characterized in that The organic solvent in step (1) is one of propanol and butanol, and the mass ratio of the organic solvent to disodium lauryl iminodipropionate is 10-30:

1.

5. The preparation method according to claim 2, characterized in that The organic solvent in step (1) is one of methanol, ethanol, isopropanol and isobutanol, and the mass ratio of the organic solvent to disodium lauryl iminodipropionate is 10-30:

1.

6. The preparation method according to claim 5, characterized in that The organic solvent is ethanol or isobutanol.

7. The preparation method according to claim 2, characterized in that The reflux time in step (1) is 24-72 hours.

8. The preparation method according to claim 2, characterized in that The solvent used for recrystallization in step (2) is one of ethyl acetate or cyclohexane.

9. Use of the organic acid salt protective fluid according to claim 1 in oil and water well casing protection.

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