A kind of oil and gas field acid liquid system and injection method

Abstract

The present invention relates to an oil and gas field acid solution system and an injection method, and relates to the technical field of oil and gas field development engineering. In terms of weight percentage, the oil and gas field acid solution system comprises the following components: 8-15% of hydrochloric acid, 3-7% of hydrofluoric acid, 1-5% of oxaloacetic acid, and 3-12% of additives; the remainder is water; the additive is obtained by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound shown in formula (I) in a weight ratio of 100:(21-37). The present invention adds oxaloacetic acid to the existing soil acid system, and simultaneously cooperates with an additive compounded with 1-heptyl-3-methylimidazolium bromide and a specific Schiff base compound, significantly improving the initial acidification speed of the system, and having excellent precipitation inhibition ability, avoiding the generation of secondary precipitation, and meeting the operating requirements of acidification of deep formations, and having good application prospects in exploitation such as sandstone reservoirs.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development engineering, and in particular to an oil and gas field acid liquid system and an injection method. Background Art

[0002] In the development and exploitation of oil and gas fields, acidizing is an important technical measure. By injecting acidic solutions (such as hydrochloric acid, hydrofluoric acid, etc.) into the formation, the acid solution is used to react chemically with carbonate rocks, clay minerals and other components in the formation rock to dissolve and corrode blockages in the formation, thereby increasing the permeability of the formation, improving the flow of oil, gas and water, and increasing the output of oil wells.

[0003] At present, the most commonly used acidizing system in oil and gas fields is soil acid formed by mixing hydrochloric acid with hydrofluoric acid. However, soil acid acidizing speed is fast, acid consumption is fast during operation, and the residual acid after reaction will form precipitation again in deep formations, which cannot meet the purpose of acidizing deep formations in actual operation. Summary of the invention

[0004] In order to solve the above problems, the present invention provides an oil and gas field acid fluid system and an injection method.

[0005] The technical solution provided by the present invention is as follows:

[0006] In a first aspect, the present invention provides an oil and gas field acid fluid system, which comprises the following components in terms of weight percentage:

[0007] Hydrochloric acid 8-15%, hydrofluoric acid 3-7%, oxaloacetic acid 1-5%, additive 3-12%; the balance is water;

[0008] The additive is prepared by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:(21-37);

[0009] The formula (I):

[0010]

[0011] Furthermore, the oil and gas field acid solution system comprises the following components in weight percentage:

[0012] Hydrochloric acid 13%, hydrofluoric acid 4.5%, oxaloacetic acid 4%, additive 9.5%; the balance is water.

[0013] Furthermore, the Schiff base compound is obtained by condensing furfural and tetrakis(4-aminophenyl)methane as reaction raw materials.

[0014] Furthermore, the molar ratio of the furfural to the tetrakis(4-aminophenyl)methane is 4:1.

[0015] Furthermore, the preparation method of the Schiff base compound comprises the following process:

[0016] dissolving tetrakis(4-aminophenyl)methane in an organic solvent to obtain a tetrakis(4-aminophenyl)methane solution;

[0017] dissolving furfural in an organic solvent to obtain a furfural solution;

[0018] Under room temperature, the tetrakis(4-aminophenyl)methane solution is added dropwise to the furfural solution at a dropping rate of 15 mL / min. After the addition is completed, the temperature is raised to 48° C. to react for 5 hours, and then the temperature is raised to 75° C. to react for 7 hours. After cooling to room temperature, the mixture is distilled under reduced pressure, washed, and dried to obtain the Schiff base compound.

[0019] Furthermore, the organic solvent includes at least one of acetone, anhydrous ethanol and acetonitrile.

[0020] Furthermore, the weight ratio of the 1-heptyl-3-methylimidazolium bromide to the Schiff base compound is 100:29.

[0021] In a second aspect, the present invention provides an oil and gas field acid liquid system injection method suitable for sandstone reservoirs, the oil and gas field acid liquid system injection method comprising injecting the oil and gas field acid liquid system described in any one of the first aspects as the main acid into the acid fracturing construction pipe string.

[0022] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0023] The invention provides an oil and gas field acid liquid system. Oxaloacetic acid is added to an existing soil acid system, and an additive prepared by compounding 1-heptyl-3-methylimidazolium bromide and a specific Schiff base compound is used in combination. The system has a significantly improved initial acidification speed, and has excellent precipitation inhibition capability, thereby avoiding the generation of secondary precipitation. The system can meet the operational requirements of acidifying deep formations, and has a good application prospect in the exploitation of sandstone reservoirs and the like. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0026] In a first aspect, the present invention provides an oil and gas field acid fluid system, which comprises the following components in terms of weight percentage:

[0027] Hydrochloric acid 8-15%, hydrofluoric acid 3-7%, oxaloacetic acid 1-5%, additive 3-12%; the balance is water;

[0028] The additive is prepared by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:(21-37);

[0029] The formula (I):

[0030]

[0031] The invention provides an oil and gas field acid liquid system. Oxaloacetic acid is added to an existing soil acid system, and an additive prepared by compounding 1-heptyl-3-methylimidazolium bromide and a specific Schiff base compound is used in combination. The system has a significantly improved initial acidification speed, and has excellent precipitation inhibition capability, thereby avoiding the generation of secondary precipitation. The system can meet the operational requirements of acidifying deep formations, and has a good application prospect in the exploitation of sandstone reservoirs and the like.

[0032] In the present invention, the CAS registration number of 1-heptyl-3-methylimidazolium bromide is 343851-32-1, and the existing commercial product can be directly purchased or prepared by itself according to the preparation process disclosed in the prior art.

[0033] In the present invention, the Schiff base compound represented by formula (I) can be directly purchased from existing commercial products or prepared in-house according to the preparation process disclosed in the prior art. In some specific embodiments, the Schiff base compound represented by formula (I) can be obtained by the following condensation reaction of furfural and tetrakis (4-aminophenyl) methane as reaction raw materials:

[0034]

[0035] In some specific embodiments, the oil and gas field acid fluid system includes the following components by weight percentage:

[0036] Hydrochloric acid 13%, hydrofluoric acid 4.5%, oxaloacetic acid 4%, additive 9.5%; the balance is water.

[0037] In some specific embodiments, the Schiff base compound is obtained by condensing furfural and tetrakis(4-aminophenyl)methane as reaction materials.

[0038] In some specific embodiments, the molar ratio of furfural to tetrakis(4-aminophenyl)methane is 4:1.

[0039] In some specific embodiments, the method for preparing the Schiff base compound comprises the following process:

[0040] dissolving tetrakis(4-aminophenyl)methane in an organic solvent to obtain a tetrakis(4-aminophenyl)methane solution;

[0041] dissolving furfural in an organic solvent to obtain a furfural solution;

[0042] Under room temperature, the tetrakis(4-aminophenyl)methane solution is added dropwise to the furfural solution at a dropping rate of 15 mL / min. After the addition is completed, the temperature is raised to 48° C. to react for 5 hours, and then the temperature is raised to 75° C. to react for 7 hours. After cooling to room temperature, the mixture is distilled under reduced pressure, washed, and dried to obtain the Schiff base compound.

[0043] In some specific embodiments, the organic solvent includes at least one of acetone, anhydrous ethanol and acetonitrile.

[0044] In some specific embodiments, the weight ratio of the 1-heptyl-3-methylimidazolium bromide to the Schiff base compound is 100:29.

[0045] In the second aspect, based on the same inventive concept, the present invention provides an oil and gas field acid liquid system injection method suitable for sandstone reservoirs, the oil and gas field acid liquid system injection method comprising using the oil and gas field acid liquid system described in any one of the first aspects as the main acid to be injected into the acid fracturing construction pipe column.

[0046] The present invention provides an oil and gas field acid liquid system injection method suitable for sandstone reservoirs. The injection method is implemented based on the oil and gas field acid liquid system described in any one of the first aspects, and therefore has at least the beneficial effects of the oil and gas field acid liquid system described in any one of the first aspects, which will not be described in detail here. At the same time, the specific implementation steps of the injection method can be carried out with reference to the existing oil and gas field acid liquid system injection method, and the present invention document will not be described one by one.

[0047] It should be noted that the raw materials involved in the oil and gas field acid liquid system and injection method provided by the present invention, unless otherwise specified or specifically described, can be directly commercially available products or homemade according to the preparation process disclosed in the prior art; at the same time, the operating steps and condition parameters involved in the oil and gas field acid liquid system and injection method, unless otherwise specified or specifically described, can be carried out according to the existing oil and gas field acid liquid system preparation process or the existing oil and gas field acid liquid system injection method, and the present invention document will not describe them one by one.

[0048] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0049] Example 1

[0050] This example provides an oil and gas field acid solution system, which includes the following components in terms of weight percentage:

[0051] Hydrochloric acid 13%, hydrofluoric acid 4.5%, oxaloacetic acid 4%, additive 9.5%; the balance is water;

[0052] The additive is prepared by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:29;

[0053] The formula (I):

[0054]

[0055] The Schiff base compound is obtained by condensing furfural and tetrakis(4-aminophenyl)methane in a molar ratio of 4:1 as reaction raw materials, and the preparation method thereof includes the following steps:

[0056] Dissolve tetrakis(4-aminophenyl)methane in acetone to obtain a tetrakis(4-aminophenyl)methane solution with a concentration of 0.03 g / mL;

[0057] Dissolve furfural in acetone to obtain a furfural solution with a concentration of 0.08 g / mL;

[0058] Under room temperature, the tetrakis(4-aminophenyl)methane solution is added dropwise to the furfural solution at a dropping rate of 15 mL / min. After the addition is completed, the temperature is raised to 48° C. for reaction for 5 hours, and then the temperature is raised to 75° C. for reaction for 7 hours. After cooling to room temperature, the solid product is distilled under reduced pressure to obtain a solid product. The solid is repeatedly washed with acetone for 3 times and dried to constant weight to obtain the Schiff base compound.

[0059] Example 2

[0060] This example provides an oil and gas field acid fluid system, which is different from Example 1 only in that the additive is obtained by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:21.

[0061] Example 3

[0062] This example provides an oil and gas field acid fluid system, which is different from Example 1 only in that the additive is obtained by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:37.

[0063] Comparative Example 1

[0064] This example provides an oil and gas field acid solution system, which is different from Example 1 only in that the amount of oxaloacetic acid is adjusted to 0 and the amount of water is adaptively increased (ie, no oxaloacetic acid is added); the remaining steps and parameters are the same.

[0065] Comparative Example 2

[0066] This example provides an oil and gas field acid solution system, which is different from Example 1 only in that 1-heptyl-3-methylimidazolium bromide is adjusted to 1-octadecyl-3-methylimidazolium bromide; the remaining steps and parameters are the same.

[0067] Comparative Example 3

[0068] This example provides an oil and gas field acid liquid system, which is different from Example 1 only in that: the Schiff base compound is adjusted to a compound represented by formula (II), wherein the compound represented by formula (II) is obtained by condensing furfural and N,N,N',N'-tetrakis(p-aminophenyl)-p-phenylenediamine in a molar ratio of 4:1 as reaction raw materials according to the preparation method in Example 1; the remaining steps and parameters are the same;

[0069] Formula (II):

[0070]

[0071] Test Case

[0072] In this example, the oil and gas field acid liquid system provided by Examples 1 to 3 and Comparative Examples 1 to 3 and the traditional soil acid system (the traditional soil acid system includes the following components in weight percentage: 13% hydrochloric acid, 4.5% hydrofluoric acid, and the balance is water) were subjected to performance testing.

[0073] 1) Test on the ability of the acidification system to inhibit the precipitation of metal ions: At 60°C, the chelating ability of the oil and gas field acid systems provided in Examples 1 to 3 and Comparative Examples 1 to 3 and the traditional soil acid system for metal ions was measured. The test results are shown in Table 1; "-" in Table 1 means "no inhibitory ability".

[0074] Test samples Calcium fluoride inhibition rate (%) Iron hydroxide inhibition rate (%) Sour soil - - Example 1 96.1 91.2 Example 2 90.5 82.7 Example 3 91.4 83.3 Comparative Example 1 61.8 50.9 Comparative Example 2 38.7 34.5 Comparative Example 3 49.6 42.0

[0075] It can be seen from Table 1 that, compared with Comparative Examples 1 to 3 and the traditional soil acid system, the oil and gas field acid solution system provided by the embodiment of the present invention has excellent precipitation inhibition ability and avoids the generation of secondary precipitation.

[0076] 2) Acidification behavior experiment of acidizing system: The same rock fragments were soaked and dissolved using Example 1 and the traditional soil acid system. The mass of the rock fragments before and after soaking was weighed to calculate the dissolution rate of the rock fragments. The variation of the dissolution rate of the fragments over time was used to characterize the acidification behavior of each acidizing system. The test results are shown in Table 2.

[0077] Table 2

[0078]

[0079] It can be seen from Table 2 that, compared with the traditional soil acid system, the oil and gas field acid system provided by the embodiment of the present invention has a slower initial acidizing rate. As the operation time increases, the debris dissolution rate gradually increases and the acidizing rate increases more slowly. Moreover, a higher debris dissolution rate can be achieved within the measurement time of 12 hours, which significantly improves the acidizing capacity of the traditional soil acid.

[0080] In summary, the present invention provides an oil and gas field acid liquid system and an injection method. By adding oxaloacetic acid to the existing soil acid system and simultaneously using an additive prepared by compounding 1-heptyl-3-methylimidazolium bromide and a specific Schiff base compound, the initial acidification speed of the system is significantly improved. At the same time, the system has excellent precipitation inhibition ability, avoids the generation of secondary precipitation, can meet the operational requirements of acidifying deep formations, and has good application prospects in the exploitation of sandstone reservoirs.

[0081] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0082] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An oil and gas field acid solution system, characterized in that: The oil and gas field acid fluid system comprises the following components in weight percentage: Hydrochloric acid 8-15%, hydrofluoric acid 3-7%, oxaloacetic acid 1-5%, additive 3-12%; the balance is water; The additive is prepared by compounding 1-heptyl-3-methylimidazolium bromide and a Schiff base compound represented by formula (I) in a weight ratio of 100:(21-37); The formula (I):

2. The oil and gas field acid solution system according to claim 1, characterized in that: The oil and gas field acid fluid system comprises the following components in weight percentage: Hydrochloric acid 13%, hydrofluoric acid 4.5%, oxaloacetic acid 4%, additive 9.5%; the balance is water.

3. The oil and gas field acid solution system according to claim 1, characterized in that: The Schiff base compound is obtained by condensing furfural and tetrakis(4-aminophenyl)methane as reaction raw materials.

4. The oil and gas field acid solution system according to claim 3, characterized in that: The molar ratio of the furfural to the tetrakis(4-aminophenyl)methane is 4:

1.

5. The oil and gas field acid solution system according to claim 4, characterized in that: The preparation method of the Schiff base compound comprises the following steps: dissolving tetrakis(4-aminophenyl)methane in an organic solvent to obtain a tetrakis(4-aminophenyl)methane solution; dissolving furfural in an organic solvent to obtain a furfural solution; Under room temperature, the tetrakis(4-aminophenyl)methane solution is added dropwise to the furfural solution at a dropping rate of 15 mL / min. After the addition is completed, the temperature is raised to 48° C. to react for 5 hours, and then the temperature is raised to 75° C. to react for 7 hours. After cooling to room temperature, the mixture is distilled under reduced pressure, washed, and dried to obtain the Schiff base compound.

6. The oil and gas field acid solution system according to claim 5, characterized in that: The organic solvent includes at least one of acetone, anhydrous ethanol and acetonitrile.

7. The oil and gas field acid solution system according to claim 1, characterized in that: The weight ratio of the 1-heptyl-3-methylimidazolium bromide to the Schiff base compound is 100:

29.

8. An acid solution system injection method for oil and gas fields suitable for sandstone reservoirs, characterized in that: The oil and gas field acid liquid system injection method comprises using the oil and gas field acid liquid system according to any one of claims 1 to 7 as a main acid and injecting it into an acid fracturing construction pipe string.

Images