Oil and gas well annulus protection fluid as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to an oil and gas well annulus protection fluid and a preparation method and application thereof. The preparation method comprises the following steps: sequentially adding 3-(4-morpholinyl)-4-fluorobenzaldehyde, dimethyl pyridylamine, sodium cyanoborohydride and ethanol into a reactor, stirring for dissolving, adjusting the pH value to 3-4 by using hydrochloric acid, and heating for reflux reaction; adjusting the pH of the mixed solution to be 1t with sulfuric acid; the method comprises the following steps: 1, stirring for 0.5-1 hour, and quenching residual sodium cyanoborohydride; adjusting the pH value to 9-10 by using sodium hydroxide, adding dodecyl bromide, heating and refluxing; and carrying out reduced pressure distillation to obtain a viscous solid, and recrystallizing with ethyl acetate to obtain the main agent of the protection liquid. And uniformly mixing the protection liquid main agent, sodium formate, sodium amino trimethylene phosphonate and water to obtain the oil and gas well annulus protection liquid. The annulus protection liquid disclosed by the invention has good anti-corrosion and sterilizing effects.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction and relates to an annular space protection fluid for oil and gas wells and a preparation method and application thereof. Background Art

[0002] When the oilfield development enters the middle and late stages, the reservoir pressure will gradually decrease as the development time increases, and the crude oil production will also decrease. Therefore, technical measures must be taken to replenish the energy of the oil layer that has begun to be produced in time to keep the oil layer at a certain pressure. Adding annular protection fluid between the oil pipe and the casing is one of the effective measures.

[0003] Annulus protection fluid is the fluid filled between the oil pipe and the oil layer casing. It has the following functions: (1) reducing the oil and gas pressure on the casing head or the packer; at the same time, it plays a certain sealing role to prevent the packer from puncturing and leaking; (2) reducing the pressure difference between the oil pipe and the annulus; (3) inhibiting the corrosion and scale tendency of the oil pipe and casing, that is, it has corrosion resistance and stability.

[0004] Therefore, density regulation, corrosion inhibition, scale inhibition and bactericidal performance become the main indicators for evaluating annular protection fluid.

[0005] CN101613598B discloses a corrosion inhibitor for inhibiting H2S / CO2 corrosion and a preparation method thereof. The corrosion inhibitor is a composition, and its composition and content are: (A) 20% to 60% by weight of imidazolidinethione derivative; (B) 5% to 20% by weight of alkynol; (C) 1% to 10% by weight of surfactant; (D) 20% to 50% by weight of solvent. The corrosion inhibitor is particularly suitable for inhibiting H2S / CO2 corrosion in oil fields. However, when there is too much unreacted thiourea in the synthetic raw materials of the annular protection fluid, corrosion will be accelerated.

[0006] CN107325803B discloses an annular protection fluid for nitrogen injection wells that can inhibit oxygen corrosion and a preparation method thereof, and belongs to the technical field of oil and gas well corrosion protection. A nitrogen injection well annular protection fluid system is compounded with 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 by mass percentage: 10%-12% imidazoline corrosion inhibitor, 0.5%-2.5% isothiazolinone bactericide, 3%-5% alkanolamine pH regulator, 6%-8% deoxidizer compounded with sulfite and oxime, 10%-20% organic acid salt density regulator, 0.5%-1.5% organic phosphonic acid scale inhibitor, and the balance is water. Under necessary conditions, an appropriate amount of anti-swelling agent should also be added. The annular protection fluid provided by the invention can well control the oxygen corrosion problem faced by the annular space of nitrogen injection wells, and at the same time has the advantages of little damage to the reservoir, strong stability, and green environmental protection. However, sulfite is added to the formula as a deoxidizer. After deoxidation, the sulfite is oxidized into sulfate. Sulfate is a nutrient for sulfate-reducing bacteria, which will cause the sulfate-reducing bacteria to multiply and further aggravate biological corrosion. Summary of the invention

[0007] The present invention aims at the above-mentioned deficiencies of the prior art and provides an oil and gas well annulus protection fluid and a preparation method thereof. The annulus protection fluid of the present invention has good antiseptic and sterilization effects.

[0008] One of the purposes of the present invention is to disclose an annulus protection fluid for oil and gas wells, the composition and mass components of the protection fluid are as follows:

[0009]

[0010] The molecular structure of the main agent of the protective liquid is as follows:

[0011]

[0012] Another object of the present invention is to disclose a method for preparing the above-mentioned oil and gas well annulus protection fluid, and the specific steps are as follows:

[0013] (1) 3-(4-morpholinyl)-4-fluorobenzaldehyde, dimethylpyridinamine, sodium cyanoborohydride, and ethanol were added to a reactor in sequence, stirred to dissolve, adjusted the pH to 3-4 with hydrochloric acid, and heated under reflux for reaction;

[0014] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for 0.5-1 hour, and quenching the remaining sodium cyanoborohydride;

[0015] (3) adjusting the pH to 9-10 with sodium hydroxide, adding dodecyl bromide, and heating to reflux;

[0016] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0017] (5) The protective liquid main agent, sodium formate, sodium aminotri(methylenephosphonic acid) acid and water are uniformly mixed to obtain an annular protective liquid for oil and gas wells.

[0018] In the present invention, preferably, based on 1 mole of 3-(4-morpholinyl)-4-fluorobenzaldehyde, the amounts of dimethylpyridinamine and dodecyl bromide used are 0.8-1.2 mole parts and 3.6-5 mole parts, respectively.

[0019] In the present invention, preferably, based on 1 part by mass of 3-(4-morpholinyl)-4-fluorobenzaldehyde, the amounts of sodium cyanoborohydride and ethanol are 0.2-0.4 parts by mass and 30-40 parts by mass, respectively.

[0020] In the present invention, preferably, the reflux reaction time in step (1) is 4-8h.

[0021] In the present invention, preferably, the reflux reaction time in step (3) is 24-72h.

[0022] In the present invention, preferably, in step (5), based on 1 part by mass of the protective liquid main agent, the amounts of sodium formate, sodium aminotri(methylenephosphonate) and water are 0.2-0.4 parts by mass, 0.05-0.1 parts by mass and 9-10 parts by mass respectively.

[0023] The reaction equation for the synthesis of the main agent of the oil and gas well annulus protection fluid of the present invention is as follows:

[0024]

[0025] The third object of the present invention is to disclose the application of the annular space protection fluid in oil and gas well exploitation.

[0026] The main agent molecule of the oil and gas well annular space protection fluid of the present invention contains four quaternary ammonium salts, which are positively charged and can be adsorbed on the metal surface to prevent hydrogen ions from approaching the metal surface, thereby protecting the metal from being corroded by acid. The four dodecyl groups are lipophilic and prevent the contact between the water phase and the metal, thereby enhancing the anti-corrosion performance. The quaternary ammonium salt and fluorine-containing morpholine in the main agent molecule have strong bactericidal properties, are easy to adsorb negatively charged bacteria, change the permeability of the cell membrane, affect the cell metabolism process, and make the bacterial protein lose activity to achieve the purpose of sterilization. Sodium formate is a typical weighting agent for the environmental control protection fluid, which can increase the density of the annular space protection fluid and better balance the formation pressure, the oil pipe pressure and the casing pressure. Sodium aminotrimethylphosphonate is a typical scale inhibitor, which can prevent the growth of scale on the metal surface, cause crystal distortion and prevent scale.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] (1) The oil and gas well annulus protection fluid of the present invention has a good anti-corrosion effect, and the corrosion inhibition rate reaches more than 92%;

[0029] (2) The oil and gas well annulus protection fluid of the present invention has a good scale inhibition effect, and the scale prevention rate reaches more than 84%;

[0030] (3) The oil and gas well annulus protection fluid of the present invention has a good bactericidal effect, and the bactericidal rate reaches 100%. DETAILED DESCRIPTION

[0031] The endpoints and any values ​​of the ranges disclosed in this article 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 endpoint values ​​of each range, the endpoint values ​​of each range and the 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 as specifically disclosed in this article.

[0032] The present invention will be further described below with reference to specific embodiments.

[0033] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0034] In the following examples and comparative examples, unless otherwise specified, all reagents used were commercially available chemically pure reagents.

[0035] Example 1

[0036] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 16 mmol dimethylpyridinamine, 0.84 g sodium cyanoborohydride, and 125 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 4 h;

[0037] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for half an hour, and quenching the remaining sodium cyanoborohydride;

[0038] (3) Adjust the pH to 9-10 with sodium hydroxide, add 72 mmol of dodecyl bromide, and heat under reflux for 24 h;

[0039] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0040] (5) 10 g of the protective liquid main agent, 2 g of sodium formate, 0.5 g of sodium aminotri(methylenephosphonic acid) acid, and 100 g of water are mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0041] Example 2

[0042] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 24 mmol dimethylpyridinamine, 0.92 g sodium cyanoborohydride, and 138 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 5 h;

[0043] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for half an hour, and quenching the remaining sodium cyanoborohydride;

[0044] (3) Adjust the pH to 9-10 with sodium hydroxide, add 80 mmol of dodecyl bromide, and heat under reflux for 72 h;

[0045] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0046] (5) 10 g of the protective liquid main agent, 2.4 g of sodium formate, 0.6 g of sodium aminotri(methylenephosphonic acid) acid, and 98 g of water were mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0047] Example 3

[0048] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 18 mmol dimethylpyridinamine, 0.98 g sodium cyanoborohydride, and 144 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 6 h;

[0049] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for half an hour, and quenching the remaining sodium cyanoborohydride;

[0050] (3) Adjust the pH to 9-10 with sodium hydroxide, add 84 mmol of dodecyl bromide, and heat under reflux for 48 h;

[0051] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0052] (5) 10 g of the protective liquid main agent, 2.8 g of sodium formate, 0.65 g of sodium aminotri(methylenephosphonic acid) acid, and 97 g of water were mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0053] Example 4

[0054] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 22 mmol dimethylpyridinamine, 1.67 g sodium cyanoborohydride, and 152 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 7 h;

[0055] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for 1 hour, and quenching the remaining sodium cyanoborohydride;

[0056] (3) Adjust the pH to 9-10 with sodium hydroxide, add 88 mmol of dodecyl bromide, and heat under reflux for 48 h;

[0057] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0058] (5) 10 g of the protective liquid main agent, 4 g of sodium formate, 0.7 g of sodium aminotri(methylenephosphonic acid) acid, and 95 g of water were mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0059] Example 5

[0060] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 19 mmol dimethylpyridinamine, 1.63 g sodium cyanoborohydride, and 167 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 6 h;

[0061] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for half an hour, and quenching the remaining sodium cyanoborohydride;

[0062] (3) Adjust the pH to 9-10 with sodium hydroxide, add 90 mmol dodecyl bromide, and heat under reflux for 50 h;

[0063] (4) distill under reduced pressure to obtain a viscous solid, which is recrystallized from ethyl acetate to obtain the main agent of the protective liquid.

[0064] (5) 10 g of the protective liquid main agent, 3.6 g of sodium formate, 0.8 g of sodium aminotri(methylenephosphonic acid) acid, and 94 g of water were mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0065] Example 6

[0066] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 20 mmol dimethylpyridinamine, 1.24 g sodium cyanoborohydride, and 160 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 8 h;

[0067] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for 1 hour, and quenching the remaining sodium cyanoborohydride;

[0068] (3) Adjust the pH to 9-10 with sodium hydroxide, add 96 mmol dodecyl bromide, and heat under reflux for 60 h;

[0069] (4) distilling under reduced pressure to obtain a viscous solid, which was recrystallized from ethyl acetate to obtain a protective liquid main agent;

[0070] (5) 10 g of the protective liquid main agent, 3.2 g of sodium formate, 0.9 g of sodium aminotri(methylenephosphonic acid) acid, and 92 g of water were mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0071] Example 7

[0072] (1) Add 20 mmol 3-(4-morpholinyl)-4-fluorobenzaldehyde, 21 mmol dimethylpyridinamine, 1.14 g sodium cyanoborohydride, and 165 g ethanol to a reactor in sequence, stir to dissolve, adjust the pH to 3-4 with hydrochloric acid, and heat under reflux for 8 h;

[0073] (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for 1 hour, and quenching the remaining sodium cyanoborohydride;

[0074] (3) Adjust the pH to 9-10 with sodium hydroxide, add 100 mmol of dodecyl bromide, and heat under reflux for 60 h;

[0075] (4) distilling under reduced pressure to obtain a viscous solid, which was recrystallized from ethyl acetate to obtain a protective liquid main agent;

[0076] (5) 10 g of the protective liquid main agent, 3 g of sodium formate, 1 g of sodium aminotri(methylenephosphonic acid) acid, and 90 g of water are mixed evenly to obtain an annular protective liquid for oil and gas wells.

[0077] Example 8 Corrosion Rate Test

[0078] 950 ml of produced water from a block of Shengli Oilfield and 50 ml of the annular space protection fluid (Example 1-7) of the present invention were mixed evenly, and the static corrosion rate at normal pressure was measured at 90°C. The test was performed with reference to SY / T 5273-2014 "Performance Indicators and Evaluation Methods for Corrosion Inhibitors for Oilfield Produced Water Treatment". The test results are shown in Table 1.

[0079] From Table 1 we can see that:

[0080] The annulus protection fluid of the present invention (Examples 1-7) has a static corrosion inhibition rate of more than 92% at normal pressure when used at a concentration of 5wt% at 90°C, with the highest reaching 95.6% (Example 7). The annulus protection fluid of the oil and gas well of the present invention has a good anti-corrosion effect.

[0081] Example 9 Evaluation of scale inhibition effect

[0082] The anti-scaling rate of CaSO4 of the annular space protection fluid (Examples 1-7) of the present invention was tested with reference to the method in SY / T5673-2020 "General Technical Conditions for Anti-scaling Agents for Oil Fields", and the test results are shown in Table 1.

[0083] From Table 1 we can see that:

[0084] The annulus protection fluid (Examples 1-7) of the present invention has a scale prevention rate of more than 84%, with the highest reaching 91.8%. The annulus protection fluid of the present invention has a good scale prevention effect.

[0085] Example 10 Evaluation of Sterilization Effect

[0086] 950 ml of produced water from a block of Shengli Oilfield and 50 ml of the annular space protection liquid (Example-7) of the present invention were taken, mixed evenly, placed in a 70°C oven, and sampled after 1 hour. The content of sulfate-reducing bacteria was detected by the extinction dilution method, and the bactericidal rate was calculated. The test results are shown in Table 1.

[0087] Table 1 Test results of corrosion inhibition, scale prevention and sterilization of annular protection fluid

[0088]

[0089]

[0090] From Table 1 we can see that:

[0091] The annulus protection fluid (Examples 1-7) of the present invention has a sterilization rate of 100% when the concentration is 5 wt % at 70° C. The annulus protection fluid of the present invention has a good sterilization effect.

[0092] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. An oil and gas well annulus protection fluid, characterized in that: The composition and mass components of the protective solution are as follows: The molecular structure of the main agent of the protective liquid is as follows:

2. The method for preparing annular space protection fluid for oil and gas wells according to claim 1, characterized in that: The specific steps of the preparation method are as follows: (1) 3-(4-morpholinyl)-4-fluorobenzaldehyde, dimethylpyridinamine, sodium cyanoborohydride, and ethanol were added to a reactor in sequence, stirred to dissolve, adjusted the pH to 3-4 with hydrochloric acid, and heated under reflux for reaction; (2) adjusting the pH of the mixed solution to <1 with sulfuric acid, stirring for 0.5-1 hour, and quenching the remaining sodium cyanoborohydride; (3) adjusting the pH to 9-10 with sodium hydroxide, adding dodecyl bromide, and heating to reflux; (4) distilling under reduced pressure to obtain a viscous solid, which was recrystallized from ethyl acetate to obtain a protective liquid main agent; (5) uniformly mixing the protective liquid main agent, sodium formate, sodium aminotri(methylenephosphonic acid) acid and water to obtain an annular protective liquid for oil and gas wells; Based on 1 mole of 3-(4-morpholinyl)-4-fluorobenzaldehyde, the amounts of dimethylpyridinamine and dodecyl bromide used are 0.8-1.2 moles and 3.6-5 moles, respectively.

3. The method for preparing annular space protection fluid for oil and gas wells according to claim 2, characterized in that: Based on 1 part by mass of 3-(4-morpholinyl)-4-fluorobenzaldehyde, the amounts of sodium cyanoborohydride and ethanol are 0.2-0.4 parts by mass and 30-40 parts by mass, respectively.

4. The method for preparing annular space protection fluid for oil and gas wells according to claim 2, characterized in that: The reflux reaction time in step (1) is 4-8h.

5. The method for preparing annular space protection fluid for oil and gas wells according to claim 2, characterized in that: The reflux reaction time in step (3) is 24-72h.

6. The method for preparing annular space protection fluid for oil and gas wells according to claim 2, characterized in that: In step (5), based on 1 part by mass of the main agent of the protective liquid, the amounts of sodium formate, sodium aminotri(methylenephosphonate) and water are 0.2-0.4 parts by mass, 0.05-0.1 parts by mass and 9-10 parts by mass respectively.

7. Use of the annulus protection fluid according to claim 1 in oil and gas well production.

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