Microemulsified acid and its use

Abstract

The present application relates to a kind of microemulsified acid and its application, wherein the microemulsified acid is formed by the microemulsion containing acid droplets in oil formed by including oleic acid, main surfactant and cosurfactant.

Description

Technical Field

[0001] This invention relates to the field of acidizing technology for oil and gas field development. Background Technology

[0002] During drilling, completion, water injection, and reservoir stimulation in carbonate oil and gas fields, the near-wellbore zone is often contaminated, leading to decreased reservoir permeability and failure to meet design injection and production rates. Due to the unique properties of carbonate minerals, acid is used to dissolve the minerals, creating acid wormholes that penetrate the near-wellbore damage zone, allowing oil and gas to flow into the wellbore. However, conventional hydrochloric acid acidizing suffers from problems such as only temporarily dissolving organic deposits, rapid reaction rates, short acid wormholes, and uneven acid distribution. Summary of the Invention

[0003] One aspect of the present invention provides a microlactic acid, which is a microemulsion containing oil-in-acid droplets formed by components including oil, acid, main surfactant and co-surfactant.

[0004] In one specific embodiment, the droplet diameter is 15 to 35 nm.

[0005] In one specific embodiment, the droplet diameter is 19 to 35 nm.

[0006] In one specific embodiment, the oil is a light oil, and the solvent is an aromatic solvent and / or a dearomatic solvent.

[0007] In one specific embodiment, the light oil is at least one selected from kerosene, cyclohexane, toluene, and limonene.

[0008] In one specific embodiment, the aromatic solvent is Solvesso 150.

[0009] In one specific embodiment, the dearomatic solvent is D40.

[0010] In one specific embodiment, the mass ratio of the light oil to the aromatic solvent and / or dearomatizing solvent is (10 to 37):(24 to 37). It should be specifically noted that when both aromatic solvent and / or dearomatizing solvent are present, the mass ratio is the ratio of the mass of the light oil to the total mass of the aromatic solvent and the dearomatizing solvent.

[0011] In one specific embodiment, the mass ratio of the light oil to the aromatic solvent and / or dearomatizing solvent is 5:16 to 37:30.

[0012] In one specific embodiment, the acid is hydrochloric acid.

[0013] In one specific embodiment, the main surfactant is a nonionic surfactant.

[0014] In one specific embodiment, the main surfactant is at least two of sorbitan fatty acid ester, sorbitan trioleate, nonylphenol polyoxyethylene ether (NP), and alkylphenol polyoxyethylene ether (OP).

[0015] In one specific embodiment, when there are two main surfactants, the mass ratio of the two surfactants is 3:5 to 1:1.

[0016] In one specific embodiment, the main surfactant is at least two of OP-10, NP-4, span85, and span80.

[0017] In one specific embodiment, the main surfactant is a mixture of OP-10 and NP-4 or a mixture of span85 and span80.

[0018] In one specific embodiment, the mass ratio of OP-10 to NP-4 in the mixture of OP-10 and NP-4 is 1:1 to 2:1.

[0019] In one specific embodiment, the mass ratio of span85 to span80 in the mixture is from 4:7 to 1:1.

[0020] In one specific embodiment, the co-surfactant is an alcohol.

[0021] In one specific embodiment, the co-surfactant is at least one of propanol to octanol.

[0022] In one specific embodiment, the co-surfactant is at least one selected from isopropanol, octanol, n-hexanol, n-pentanol, and n-butanol.

[0023] In one specific embodiment, when there are two types of co-surfactants, the mass ratio of the two co-surfactants is 4:7 to 2:1.

[0024] In one specific embodiment, the mass ratio of the main surfactant to the co-surfactant is 1:1 to 11:8.

[0025] In one specific embodiment, the total amount of the microlactic acid is 100%, the oil content is 34% to 67%, the acid content is less than 30%, and the total content of the main surfactant and the co-surfactant is 18% to 36%.

[0026] In one specific embodiment, the acid content is 15% to 30%.

[0027] The second invention provides the application of microlactic acid according to any one of the inventions in unclogging organic and / or inorganic deposits, particularly in unclogging carbonate wells.

[0028] The beneficial effects of this invention are:

[0029] The microlactic acid provided by this invention can remove organic, inorganic, and mixed deposits from formations, achieving a 100% solubility for all types of scale. It also possesses high-temperature resistance, strong slowing properties (slowing rate exceeding 99%), and viscosity sufficient to suspend temporarily plugging fibers, thus enabling deep reservoir unblocking. Furthermore, using the microlactic acid provided by this invention simplifies the construction process, saves construction time, and achieves cost reduction and efficiency improvement, which is of great significance for oil and gas field development and exploitation. Attached Figure Description

[0030] Figure 1 The particle size distribution of the microlactic acid prepared in Example 1 is shown. Detailed Implementation

[0031] The present invention will be further described in detail below through preferred embodiments, but these embodiments do not constitute a limitation thereof.

[0032] Unless otherwise specified, all reagents used in the embodiments of this invention are commercially available.

[0033] Example 1

[0034] Weigh 30 parts by mass of concentrated hydrochloric acid (36% by mass), 9 parts by mass each of OP-10, NP-4, octanol, and isopropanol, 24 parts by mass of the aromatic solvent Solvesso 150, and 10 parts by mass of kerosene. Add these to a container and mix thoroughly to obtain an oil-in-acid type upper-phase microlactic acid. The liquid particle size of the oil-in-acid was measured by dynamic light scattering, with a median particle size of 18.9 nm. The particle size distribution is shown in [Figure showing particle size distribution]. Figure 1 .

[0035] This microlactic acid system is transparent and has a stability of over 30 days.

[0036] Example 2

[0037] Weigh out 30 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 8 parts by mass of OP-10, 4 parts by mass of NP-4, 4 parts by mass of octanol, 6 parts by mass of isopropanol, 32 parts by mass of aromatic solvent Solvesso 150, and 16 parts by mass of kerosene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 33.0 nm.

[0038] This microlactic acid system is transparent and has a stability of over 30 days.

[0039] Example 3

[0040] Weigh out 30 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 6 parts by mass of OP-10, 5 parts by mass of NP-4, 9 parts by mass of n-hexanol, 34 parts by mass of aromatic solvent Solvesso 150, and 16 parts by mass of limonene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 35.3 nm.

[0041] This microlactic acid system is transparent and has a stability of over 30 days.

[0042] Example 4

[0043] Weigh 25 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 6 parts by mass of OP-10, 6 parts by mass of NP-4, 9 parts by mass of n-pentanol, 35 parts by mass of dearomatic hydrocarbon D40 solvent oil, and 19 parts by mass of toluene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 29.7 nm.

[0044] This microlactic acid system is transparent and has a stability of over 30 days.

[0045] Example 5

[0046] Weigh out 16 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 4 parts by mass of Span80 (sorbitan fatty acid ester), 7 parts by mass of Span85 (sorbitan trioleate), 3 parts by mass of n-butanol, 5 parts by mass of octanol, 37 parts by mass of aromatic solvent Solvesso 150, and 28 parts by mass of kerosene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 25.9 nm.

[0047] This microlactic acid system is transparent and has a stability of over 30 days.

[0048] Example 6

[0049] Weigh out 15 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 5 parts by mass of Span80 (sorbitan fatty acid ester), 5 parts by mass of Span85 (sorbitan trioleate), 3 parts by mass of isopropanol, 5 parts by mass of octanol, 37 parts by mass of dearomatic D40 solvent oil, and 37 parts by mass of kerosene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 32.1 nm.

[0050] This microlactic acid system is transparent and has a stability of over 30 days.

[0051] Comparative Example 1

[0052] Weigh out 35 parts of concentrated hydrochloric acid with a mass content of 36%, 10 parts each of octanol, isopropanol, OP-10 and NP-4, 15 parts of Solvesso 150 aromatic solvent, and 10 parts of kerosene. Then add them to a container and mix well. The system is turbid and the oil and water separate after 2 minutes.

[0053] Comparative Example 2

[0054] Weigh 30 parts by mass of concentrated hydrochloric acid with a mass content of 36%, 9 parts by mass each of octanol, isopropanol, OP-10 and NP-4, and 34 parts by mass of kerosene. Then add them to a container and mix them evenly to obtain oil-in-acid type upper phase microlactic acid. The liquid particle size of oil-in-acid was measured by dynamic light scattering method, and the median particle size was 12.3 nm.

[0055] Comparative Example 3

[0056] 100 parts by weight of Solvesso 150.

[0057] Comparative Example 4

[0058] Preparation of emulsified acids:

[0059] 1) Prepare a 20% hydrochloric acid aqueous solution using concentrated hydrochloric acid.

[0060] 2) Taking the mass of the 20% hydrochloric acid aqueous solution as 100%, add 1% of DCA-6 acid corrosion inhibitor (Beijing Kemaishi Oilfield Chemical Agent Technology Co., Ltd.) to the 20% hydrochloric acid aqueous solution, and stir it for 3 minutes at 10000 rpm using a homogenizer to obtain the acid phase.

[0061] 3) Mix 93 parts by volume of diesel oil (density 0.841 g / mL, 20℃) and 7 parts by volume of EEA emulsifier (Beijing Hongyi Enze Energy Technology Co., Ltd.), and stir at 15000 rpm for 3 minutes to obtain the oil phase.

[0062] 4) Slowly add the acid phase to the oil phase at a volume ratio of 7:3 and stir at 15,000 rpm for 30 minutes to obtain emulsified acid.

[0063] This emulsified acid has a resistivity of 18.2 MΩ·cm and a density of 1.08 g / mL at room temperature, and can withstand temperatures above 120℃.

[0064] Comparative Example 5

[0065] Preparation of gelling acid:

[0066] 1) Prepare a 20% hydrochloric acid aqueous solution using concentrated hydrochloric acid.

[0067] 2) Stir a 20% hydrochloric acid aqueous solution at a speed of 2000 rpm in a mixer. Taking the mass of the 20% hydrochloric acid aqueous solution as 100%, slowly add 0.6% carboxymethyl hydroxypropyl guar gum to it until the powder is completely dissolved to obtain gelled acid.

[0068] The density of this gelling acid is 1.10 g / mL.

[0069] Comparative Example 6

[0070] Hydrochloric acid with a mass concentration of 20%.

[0071] Performance testing:

[0072] 1. Determination of scale dissolution rate

[0073] The scale dissolution rate was determined according to the "YF 338-2016 Method for Determining the Dissolution Rate of Acidic Rock Powder": At 90℃, 10g of organic scale asphalt and 10g of inorganic scale calcium carbonate were mixed and placed in 100g of microlactic acid in each example, and reacted at 70℃ for 4 hours. The scale dissolution rate was calculated and is shown in Table 1.

[0074] 2. Determination of slow rate

[0075] The retardation rate was determined according to the "SY / T 5886-2012 Method for Evaluating the Performance of Retarded Acid". Under the condition of 40℃, 25g of limestone core with calcite content of more than 95% was placed in 100g of microlactic acid in each example and reacted for 1 hour. The erosion rate was measured and the retardation rate was calculated as shown in Table 1.

[0076] Table 1

[0077] Example scale dissolution rate slow rate Example 1 100％ 99.9％ Example 2 100％ 99.9％ Example 3 100％ 99.9％ Example 4 100％ 99.8％ Example 5 100％ 99.8％ Example 6 100％ 99.8％

[0078] 3. Determination of the ability to dissolve organic scale

[0079] 80g of the products from Examples 1 to 6 and Comparative Examples 2 and 3 were placed in a water bath at 40°C. The asphalt was cut into squares with a length, width, and height of approximately 2.6 to 2.7cm. After weighing, the asphalt was added to the product and dissolved for 30 minutes. Then, it was dried at 105°C for 24 hours. The remaining asphalt was weighed, and the mass of dissolved asphalt and the mass of dissolved asphalt per unit product were calculated. The results are shown in Table 2.

[0080] Table 2

[0081] Example Before dissolution (g) After dissolution (g) Dissolved asphalt content (g) Unit product soluble asphalt content (g / g) Example 1 23.8915 22.5342 1.3573 0.0499 Example 2 24.8976 23.0990 1.7986 0.0468 Example 3 23.9764 22.1867 1.7897 0.0447 Example 4 25.1387 23.2716 1.8671 0.0432 Example 5 24.3879 22.1732 2.2147 0.0426 Example 6 24.5700 22.1985 2.3715 0.0442 Comparative Example 2 24.9527 24.642 0.3107 0.0114 Comparative Example 3 25.2153 22.8996 1.8698 0.0234

[0082] As can be seen from the data in Table 2, the product of the present invention has a significantly better ability to dissolve asphalt than the comparative example.

[0083] 4. Determination of the ability to dissolve inorganic scale

[0084] The hydrogen ion mass transfer rate was determined and calculated according to RABIE AI, GOMAA AM, NASR-EL-DIN H A. Reaction of in-situ-gelledacids with calcite:reaction-rate study[J]. SPE Journal, 2011, 16(04): 981-992.

[0085] The rotating disk reactor mainly consists of a storage container, a reaction vessel, a rotating disk assembly, and a control panel. The storage container heats the test liquid to the target temperature during the preheating stage. The reaction vessel contains a magnetically driven rotating disk. A reaction core (approximately 1 inch in diameter) is fixed by a PTFE thermoplastic tube. The required pressure for the reaction is provided by adding inert gas N2. All components that frequently come into contact with the test liquid are made of acid-resistant Hastelloy. The radius of the reaction vessel and the axial distance between the bottom of the disk and the bottom of the reaction vessel affect the flow pattern of the test liquid within the reaction vessel. The reaction vessel used in this invention can hold approximately 550 mL of test liquid, has a diameter of 77.30 mm, a height of 118.10 mm, a core sample height of 23 ± 0.2 mm, and an axial distance between the bottom of the disk and the bottom of the reaction vessel of approximately 32 mm.

[0086] The specific experimental steps are as follows:

[0087] The products of Examples 1 to 6 and Comparative Examples 4 to 6 were used as test solutions.

[0088] Experimental preparation: The core was fixed in a thermoplastic tube and placed into the reaction vessel. 550 mL of the test solution was injected into the storage container. The target temperature was set to 70 °C. After transferring the test solution from the storage container to the reaction vessel, the pressure was increased to 1 MPa. The overall pressure was then increased to 7.5 MPa.

[0089] Operation and Sampling: Set the rotation speed and start the experiment. Immediately after starting, sample the test solution from the sampling storage, discarding the sample from the first few seconds to eliminate the influence of residual liquid in the sample chamber. Each experiment lasts 15 minutes, with sample collection every 3 minutes to avoid excessive sampling time and eliminate the influence of surface area on the acid-rock reaction rate. The initial surface area and porosity of the core are used to determine the acid-rock reaction rate.

[0090] Data processing: After the experiment, the core sample was removed and the surface was slowly washed with deionized water. It was then placed in an oven at 105℃ and dried for 24 hours. The mass was recorded as M2. Since the main acid in the test solution was hydrochloric acid, the acid-rock reaction amount was calculated by titration. 1.0 mL of the sample was taken and diluted 10 times to amplify the concentration difference between the titrated acid solutions. The sampled acid solution was titrated with a low concentration of NaOH solution (calibrated molar concentration: 0.1037 mol / L) and phenol red indicator to reduce the error of this method.

[0091] The results are shown in Table 3.

[0092] Table 3

[0093] Example Hydrogen ion mass transfer rate Example 1 <![CDATA[8.177E-08cm 2 / s]]> Example 2 <![CDATA[7.968E-08cm 2 / s]]> Example 3 <![CDATA[7.167E-08cm 2 / s]]> Example 4 <![CDATA[5.987E-08cm 2 / s]]> Example 5 <![CDATA[3.468E-08cm 2 / s]]> Example 6 <![CDATA[3.315E-08cm 2 / s]]> Comparative Example 4 <![CDATA[3.163E-07cm 2 / s]]> Comparative Example 5 <![CDATA[1.251E-06cm 2 / s]]> Comparative Example 6 <![CDATA[2.402E-05cm 2 / s]]>

Claims

1. A microlactic acid, which is a microemulsion containing oil-in-acid droplets formed by components including oil, acid, main surfactant and co-surfactant; The oil is a light oil, and an aromatic solvent and / or a dearomatic solvent; The mass ratio of the light oil to the aromatic solvent and / or dearomatizing solvent is (10 to 37): (24 to 37); The main surfactant is a mixture of OP-10 and NP-4 or a mixture of Span85 and Span80; In the mixture of OP-10 and NP-4, the mass ratio of OP-10 to NP-4 is 1:1 to 2:1; In the mixture of span85 and span80, the mass ratio of span80 to span85 is 4:7 to 1:1; The mass ratio of the main surfactant to the co-surfactant is 1:1 to 11:

8.

2. The microlactic acid according to claim 1, characterized in that, The droplets have a diameter of 15 to 35 nm.

3. The microlactic acid according to claim 1, characterized in that, The light oil is at least one of kerosene, cyclohexane, toluene, and limonene; The aromatic solvent is Solvesso 150; The dearomatic solvent is D40.

4. The microlactic acid according to claim 1, characterized in that, The acid is hydrochloric acid.

5. The microlactic acid according to claim 1, characterized in that, The co-surfactant is an alcohol.

6. The microlactic acid according to claim 1, characterized in that, The co-surfactant is at least one of propanol to octanol.

7. The microlactic acid according to claim 1, characterized in that, The co-surfactant is at least one selected from isopropanol, octanol, n-hexanol, n-pentanol, and n-butanol.

8. The microlactic acid according to claim 1, characterized in that, The total amount of the microlactic acid is taken as 100%, the oil content is 34% to 67%, the acid content is less than 30%, and the total content of the main surfactant and the co-surfactant is 18% to 36%.

9. The application of microlactic acid according to any one of claims 1 to 8 in unclogging organic and / or inorganic scale deposits.

10. The application of microlactic acid according to any one of claims 1 to 8 in unclogging carbonate wells.

Images