A water-based drilling fluid inhibitor and its preparation method

Abstract

The present invention discloses an inhibitor for water-based drilling fluid and a preparation method thereof. The raw materials required for the inhibitor of the present invention include 0.05 mol - 1 mol of perfluoropolyether carboxylic acid, 0.05 mol - 1 mol of thionyl chloride, 0.005 mol - 0.1 mol of pyridine, and 0.1 mol - 2 mol of hexamethylenediamine, and ethyl acetate is used as a solvent; the inhibitor of the present invention has good compatibility with conventional water-based treatment agents, maintains good inhibition performance, can effectively enhance the inhibition ability of water-based drilling fluid, and achieves the effect of inhibiting the hydration and dispersion of minerals in water-sensitive formations.

Description

Technical Field

[0001] The present invention relates to the technical field of inhibitors for drilling fluids, and more particularly to an inhibitor for water-based drilling fluids and a preparation method thereof. Background Art

[0002] When drilling with water-based drilling fluids in water-sensitive formations, clay minerals in the formation are prone to hydration swelling and dispersion, resulting in problems such as wellbore instability and deterioration of the rheological properties of the drilling fluid. Therefore, the inhibition performance of the drilling fluid system has become one of the key technologies for safe and rapid drilling in water-sensitive formations.

[0003] Common inhibitors for water-based drilling fluids are mainly potassium salts, ammonium salts, and amine (ammonium) polymer inhibitors. Such inhibitors mainly adsorb on the surface of negatively charged clay minerals through electrostatic force or hydrogen bonds between cations and amino groups or amide groups, thereby inhibiting the hydration of clay minerals. In actual application, the formulation of the water-based drilling fluid system is complex. In addition to containing a certain amount of bentonite material, some treatment agents also have negative charges. As a result, after such inhibitors are added to the water-based drilling fluid system, they adsorb with bentonite and negatively charged treatment agents in the water-based drilling fluid through electrostatic force or hydrogen bond force, losing the inhibitory effect on formation clay minerals and reducing the inhibition performance of the water-based drilling fluid system.

[0004] This often shows that when evaluating with inhibitor single agents through the rolling recovery rate of mudstone, there is often an obvious inhibitory effect, and the improvement value of the recovery rate compared with the blank sample is also relatively high. However, after adding the inhibitor to the drilling fluid system for evaluation, it will be found that the improvement effect of the inhibitor on the recovery rate is very limited. This is mainly because after adding the inhibitor to the drilling fluid system, the inhibitor adsorbs with the negatively charged materials in the drilling fluid system in advance, so that it cannot be effectively adsorbed on the surface of clay minerals to achieve the inhibitory effect.

[0005] To solve the technical problem of the reduction of inhibition performance caused by the premature adsorption of the inhibitor for water-based drilling fluids with negatively charged materials, it is necessary to develop a new inhibitor to solve the technical problem of premature adsorption of the inhibitor with negatively charged materials, improve the inhibition effect of the water-based drilling fluid system, effectively relieve the water-sensitive instability and cuttings hydration dispersion of water-sensitive formations, meet the technical needs of high-quality, safe and rapid drilling in water-sensitive formations on site, and improve the exploration and development efficiency. Summary of the Invention

[0006] In order to overcome the defects and deficiencies existing in the above-mentioned prior art, the present invention provides an inhibitor for water-based drilling fluid and a preparation method thereof. The object of the present invention is to solve the technical problem of premature adsorption of the inhibitor and negatively charged materials, improve the inhibition effect of the water-based drilling fluid system, relieve the water-sensitive instability of water-sensitive formations and the hydration dispersion of cuttings, so as to meet the technical requirements of high-quality, safe and rapid drilling in water-sensitive formations on site and improve the exploration and development efficiency. The raw materials required for the inhibitor of the present invention include perfluoropolyether carboxylic acid, thionyl chloride, pyridine, hexamethylenediamine and ethyl acetate; the inhibitor of the present invention has good compatibility with conventional water-based treatment agents, maintains good inhibition performance, can effectively strengthen the inhibition ability of the water-based drilling fluid, and achieves the effect of inhibiting the hydration dispersion of minerals in water-sensitive formations.

[0007] In the first aspect of the present invention, an inhibitor for water-based drilling fluid is provided. In terms of the amount of substance, the inhibitor for water-based drilling fluid comprises the following raw materials:

[0008] 0.05 mol - 1 mol of perfluoropolyether carboxylic acid;

[0009] 0.05 mol - 1 mol of thionyl chloride;

[0010] 0.005 mol - 0.1 mol of pyridine;

[0011] 0.1 mol - 2 mol of hexamethylenediamine;

[0012] Ethyl acetate is used as a solvent.

[0013] Further preferably, the molar ratio between the components is: perfluoropolyether carboxylic acid: thionyl chloride: pyridine: hexamethylenediamine = 1:1:0.1:2.

[0014] Further preferably, in terms of the amount of substance, the inhibitor for water-based drilling fluid comprises the following raw materials:

[0015] 1 mol of perfluoropolyether carboxylic acid;

[0016] 1 mol of thionyl chloride;

[0017] 0.1 mol of pyridine;

[0018] 2 mol of hexamethylenediamine.

[0019] Further preferably, the molecular weight of the perfluoropolyether carboxylic acid is 1000 - 10000.

[0020] In the second aspect of the present invention, a preparation method of an inhibitor for water-based drilling fluid is provided. The preparation method comprises the following steps:

[0021] S1. Add 0.05 mol - 1 mol of perfluoropolyether carboxylic acid into a three-necked flask equipped with a stirring device, a reflux condenser and a thermometer, and start stirring;

[0022] S2. Slowly drop 0.05 mol - 1 mol of thionyl chloride and 0.005 mol - 0.1 mol of pyridine into a three-necked flask after mixing them.

[0023] S3. Heat the three-necked flask, raise the temperature to 80°C - 90°C, reflux for 3 h - 5 h, and then cool to room temperature.

[0024] S4. Add 0.1 mol - 2 mol of hexamethylenediamine and ethyl acetate to the three-necked flask.

[0025] S5. Reflux at 80°C - 85°C for 2 h - 3 h, distill off all the ethyl acetate, raise the temperature to 130°C and reflux for 24 h, cool to room temperature, add the product in the three-necked flask to a separatory funnel, and take the upper reddish-brown product as the target product.

[0026] Among them, for the distillation and removal of ethyl acetate in step S5, a condenser in a roughly vertical direction is used to condense the vaporized ethyl acetate and reflux it back to the flask. After 2 - 3 h of reflux and reaction, connect the flask with a bent tube, and then connect the condenser in a roughly horizontal direction. At the same temperature, distill the ethyl acetate out of the flask.

[0027] Further preferably, in the above preparation method, the molar ratio between the components is: perfluoropolyether carboxylic acid: thionyl chloride: pyridine: hexamethylenediamine = 1:1:0.1:2.

[0028] Further preferably, in the above preparation method, the dosages of each component are as follows:

[0029] 1 mol of perfluoropolyether carboxylic acid;

[0030] 1 mol of thionyl chloride;

[0031] 0.1 mol of pyridine;

[0032] 2 mol of hexamethylenediamine.

[0033] Further preferably, the molecular weight of the perfluoropolyether carboxylic acid is 1000 - 10000.

[0034] The reaction mechanism between the raw materials of the drilling fluid inhibitor is specifically as follows:

[0035]

[0036]

[0037] ;

[0038] Among them, the raw material pyridine mainly acts as a catalyst for the chlorination reaction of perfluoropolyether carboxylic acid and thionyl chloride; ethyl acetate mainly acts as a solvent.

[0039] Compared with the prior art, the beneficial technical effects brought by the present invention are as follows:

[0040] 1. The water-based drilling fluid inhibitor of the present invention has good compatibility with conventional water-based treatment agents, maintains good inhibition performance, can effectively enhance the inhibition ability of water-based drilling fluids, and achieves the effect of inhibiting the hydration and dispersion of minerals in water-sensitive formations.

[0041] 2. The inhibitor of the present invention has good chemical stability and can maintain good stability in the high-temperature downhole environment. The inhibitor of the present invention will not dissolve in water-based drilling fluids, but can be emulsified and dispersed by high-speed stirring and dispersed in water-based drilling fluids in the form of droplets, effectively alleviating the adsorption effect on negatively charged treatment agents and avoiding the reduction of inhibition effect caused by premature adsorption. Perfluoropolyether carboxylic acid has strong hydrophobicity, resulting in the hydrophobicity of the formed perfluoropolyether amide, which is insoluble in water and is dispersed into emulsion droplets under the effect of drilling fluid emulsifiers and high-shear stirring.

[0042] 3. The inhibitor of the present invention has strong hydrophobicity. After adsorbing and binding with water-sensitive clay minerals, it can effectively alleviate the intrusion of the water phase into clay minerals and greatly improve the inhibition effect of the inhibitor. Detailed implementation manners

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0044] Example 1

[0045] As a preferred embodiment of the present invention, this embodiment provides a water-based drilling fluid inhibitor, which, in terms of the amount of substance, comprises the following raw materials: 0.25 mol of perfluoropolyether carboxylic acid, 0.25 mol of thionyl chloride, 0.025 mol of pyridine, 0.5 mol of ethylenediamine, and 80 mL of ethyl acetate. The molecular weight of perfluoropolyether carboxylic acid is about 1000; the solvent ethyl acetate is reasonably selected according to the amounts of other components; it should not be excessive, as excessive amounts will cause too long a time for subsequent distillation to remove ethyl acetate.

[0046] Example 2

[0047] As another preferred embodiment of the present invention, this embodiment provides a water-based drilling fluid inhibitor. In terms of the amount of substance, the raw materials of the water-based drilling fluid inhibitor include: 0.125 mol of perfluoropolyether carboxylic acid, 0.125 mol of thionyl chloride, 0.0125 mol of pyridine, 0.25 mol of ethylenediamine, and 90 mL of ethyl acetate. The molecular weight of the perfluoropolyether carboxylic acid is about 2500. The solvent ethyl acetate is reasonably selected according to the amounts of other components; it should not be excessive, as excessive amounts will cause the subsequent distillation to remove ethyl acetate to take too long.

[0048] Example 3

[0049] As another preferred embodiment of the present invention, this embodiment provides a water-based drilling fluid inhibitor. In terms of the amount of substance, the raw materials of the water-based drilling fluid inhibitor include: 0.05 mol of perfluoropolyether carboxylic acid, 0.05 mol of thionyl chloride, 0.005 mol of pyridine, 0.1 mol of ethylenediamine, and 0.2 mol of ethyl acetate. The molecular weight of the perfluoropolyether carboxylic acid is about 8000. The solvent ethyl acetate is reasonably selected according to the amounts of other components; it should not be excessive, as excessive amounts will cause the subsequent distillation to remove ethyl acetate to take too long.

[0050] Example 4

[0051] As a preferred embodiment of the present invention, this embodiment provides a water-based drilling fluid inhibitor. In terms of the amount of substance, the raw materials of the water-based drilling fluid inhibitor include: 0.04 mol of perfluoropolyether carboxylic acid (molecular weight 10000), 0.04 mol of thionyl chloride, 0.004 mol of pyridine, 0.08 mol of ethylenediamine, and 100 mL of ethyl acetate. The molecular weight of the perfluoropolyether carboxylic acid is about 10000. The solvent ethyl acetate is reasonably selected according to the amounts of other components; it should not be excessive, as excessive amounts will cause the subsequent distillation to remove ethyl acetate to take too long.

[0052] Example 5

[0053] As a preferred embodiment of the present invention, this embodiment provides a water-based drilling fluid inhibitor. In terms of the amount of substance, the raw materials of the water-based drilling fluid inhibitor include: 1 mol of perfluoropolyether carboxylic acid (molecular weight 1000), 1 mol of thionyl chloride, 0.1 mol of pyridine, 2 mol of ethylenediamine, and 320 mL of ethyl acetate. The molecular weight of the perfluoropolyether carboxylic acid is about 1000. The solvent ethyl acetate is reasonably selected according to the amounts of other components; it should not be excessive, as excessive amounts will cause the subsequent distillation to remove ethyl acetate to take too long.

[0054] Example 6

[0055] As another preferred embodiment of the present invention, this embodiment provides a preparation method of the water-based drilling fluid inhibitor in the above-mentioned Example 1. The preparation method includes:

[0056] S1. Add 0.25 mol of perfluoropolyether carboxylic acid (molecular weight about 1000) into a three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and start stirring.

[0057] S2. Slowly drop 0.25 mol of thionyl chloride and 0.025 mol of pyridine into the three-necked flask.

[0058] S3. Raise the temperature to 84 °C, reflux for 4 h, and then cool to room temperature.

[0059] S4. Add 0.5 mol of ethylenediamine and ethyl acetate into the three-necked flask.

[0060] S5. Reflux at 82 °C for 2 h, distill off all the ethyl acetate, and then raise the temperature to 130 °C and reflux for 24 h.

[0061] Cool to room temperature, add the product in the three-necked flask into a separatory funnel to obtain 138.62 g of the upper layer of brownish-red product perfluoropolyether amide.

[0062] Example 7

[0063] As another preferred embodiment of the present invention, this embodiment provides a preparation method of the water-based drilling fluid inhibitor in the above Example 2. The preparation method includes:

[0064] S1. Add 0.125 mol of perfluoropolyether carboxylic acid (molecular weight about 2500) into a three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and start stirring.

[0065] S2. Slowly drop 0.125 mol of thionyl chloride and 0.0125 mol of pyridine into the three-necked flask.

[0066] S3. Raise the temperature to 85 °C, reflux for 5 h, and then cool to room temperature.

[0067] S4. Add 0.25 g of hexamethylenediamine and ethyl acetate into the three-necked flask.

[0068] S5. Reflux at 85 °C for 3 h, distill off all the ethyl acetate, and then raise the temperature to 130 °C and reflux for 24 h.

[0069] Cool to room temperature, add the product in the three-necked flask into a separatory funnel to obtain 176.43 g of the upper layer of brownish-red product perfluoropolyether amide.

[0070] Example 8

[0071] As another preferred embodiment of the present invention, this embodiment provides a preparation method of the water-based drilling fluid inhibitor in the above Example 3. The preparation method includes:

[0072] S1. Add 0.05 mol of perfluoropolyether carboxylic acid (molecular weight about 8000) into a three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and start stirring.

[0073] S2. Slowly drop 0.05 mol of thionyl chloride and 0.005 mol of pyridine into the three-necked flask.

[0074] S3. Raise the temperature to 87 °C, reflux for 5 h, and then cool to room temperature.

[0075] S4. Add 0.1 mol of hexamethylenediamine and ethyl acetate into the three-necked flask.

[0076] S5. Reflux at 81 °C for 3 h, distill off all the ethyl acetate, raise the temperature to 130 °C and reflux for 24 h. Cool to room temperature, add the product in the three-necked flask into a separatory funnel to obtain 239.15 g of the upper layer of brownish-red product perfluoropolyether amide.

[0077] Example 9

[0078] As another preferred embodiment of the present invention, this embodiment provides a preparation method of the water-based drilling fluid inhibitor in the above Example 4, and the preparation method includes:

[0079] S1. Add 0.04 mol of perfluoropolyether carboxylic acid (molecular weight about 10000) into a three-necked flask equipped with a stirrer, a reflux condenser and a thermometer, and start stirring.

[0080] S2. Slowly drop 0.04 mol of thionyl chloride and 0.004 mol of pyridine into the three-necked flask.

[0081] S3. Raise the temperature to 84 °C, reflux for 4 h, and then cool to room temperature.

[0082] S4. Add 0.08 mol of ethylenediamine and ethyl acetate into the three-necked flask.

[0083] S5. Reflux at 82 °C for 2 h, distill off all the ethyl acetate, raise the temperature to 130 °C and reflux for 24 h.

[0084] Cool to room temperature, add the product in the three-necked flask into a separatory funnel to obtain 243.12 g of the upper layer of brownish-red product perfluoropolyether amide.

[0085] In the above Examples 6-9, for the distillation and removal of ethyl acetate, a condensable tube in a substantially vertical direction is used to condense the vaporized ethyl acetate and reflux it into the flask. After 2-3 h of reflux and reaction are completed, the flask is connected with a bent tube, and then a condensable tube is connected in a substantially horizontal direction. At the same temperature, the ethyl acetate is distilled out of the flask.

[0086] Example 10

[0087] The inhibition effects of Example 6, Example 7, Example 8, polyamide inhibitor, and potassium formate were evaluated by a rolling recovery rate experiment.

[0088] Take 5 portions of 350 mL of distilled water. Add 1% of Example 6, 1% of Example 7, 1% of Example 8, and 1% of polyamine inhibitor to 4 of these portions respectively, and stir on a high-speed stirrer (11,000 rpm / min) for 10 min. Take 1 portion of 350 mL of 40% potassium formate solution. Add the 6 portions of liquid into an aging tank respectively, and then add 50 g of shale cuttings respectively. Roll and age at 150 °C for 16 hours, and measure the rolling recovery rate. The results are shown in Table 1.

[0089] Table 1 Comparison of rolling recovery rates of perfluoropolyether amide and other common inhibitors for shale cuttings in clear water

[0090]

[0091] It can be seen from Table 1 that the rolling recovery rates of Examples 6, 7, and 8 are significantly higher than that of potassium formate and are basically equivalent to the recovery rate of the polyamine inhibitor. This indicates that in distilled water, the inhibition effect of the perfluoropolyether amide inhibitor is significantly better than that of potassium formate and is equivalent to that of the polyamine inhibitor, demonstrating that the perfluoropolyether amide inhibitor has a good inhibition effect.

[0092] Take 6 portions of 350 mL of water-based drilling fluid. Add 1% of Example 6, 1% of Example 7, 1% of Example 8, and 1% of polyamine inhibitor to 4 of these portions respectively, and stir on a high-speed stirrer (11,000 rpm / min) for 10 min; add 40% potassium formate to 1 portion of 350 mL of water-based drilling fluid, stir on a high-speed stirrer (11,000 rpm / min) for 10 min until the potassium formate is completely dissolved, and measure 350 mL. Add the 6 portions of drilling fluid into an aging tank respectively, and then add 50 g of shale cuttings respectively. Roll and age at 150 °C for 16 hours, and measure the rolling recovery rate. The results are shown in Table 2.

[0093] Table 2 Comparison of rolling recovery rates of perfluoropolyether amide and other common inhibitors for shale cuttings in drilling fluid

[0094]

[0095] Combining Table 1 and Table 2, it can be seen that in fresh water, the recovery rates of the polyamine inhibitor and the perfluoropolyether amide inhibitor are basically equivalent. However, in the water-based drilling fluid, the recovery rate of the perfluoropolyether amide inhibitor increases significantly and is also much higher than that of the polyamine inhibitor. This is mainly because inhibitors such as potassium formate and polyamine inhibitor are fully dissolved after being added to the water-based drilling fluid and adsorb with the negatively charged treatment agents in the drilling fluid, resulting in a reduction in their inhibition effect. The perfluoropolyether amide inhibitor is insoluble in the aqueous phase and contacts with the negatively charged treatment agents in the drilling fluid through sufficient emulsification and dispersion, and the mutual adsorption effect is greatly alleviated, thus avoiding the decrease in the inhibition effect caused by the adsorption of negatively charged materials and effectively ensuring the inhibition effect of this treatment agent in the drilling fluid.

Claims

1. A water-based drilling fluid inhibitor, characterized in that: Comprising the following raw materials in terms of amount of substance, 0.05 mol - 1 mol of perfluoropolyether carboxylic acid; 0.05 mol - 1 mol of thionyl chloride; 0.005 mol - 0.1 mol of pyridine; 0.1 mol - 2 mol of hexamethylenediamine; Using ethyl acetate as the solvent; pyridine as the catalyst for the reaction of perfluoropolyether carboxylic acid and thionyl chloride, and perfluoropolyether carboxylic acid, thionyl chloride and hexamethylenediamine as the reactants, the resulting perfluoropolyether amide is the water-based drilling fluid inhibitor.

2. The water-based drilling fluid inhibitor according to claim 1, characterized in that: The molar ratio between the components is: perfluoropolyether carboxylic acid: thionyl chloride: pyridine: hexamethylenediamine = 1:1:0.1:

2.

3. The water-based drilling fluid inhibitor according to claim 1 or 2, characterized in that: The water-based drilling fluid inhibitor comprises the following raw materials in terms of amount of substance: 1 mol of perfluoropolyether carboxylic acid; 1 mol of thionyl chloride; 0.1 mol of pyridine; 2 mol of hexamethylenediamine.

4. The water-based drilling fluid inhibitor according to claim 1 or 2, characterized in that: The molecular weight of the perfluoropolyether carboxylic acid is 1000 - 10000.

5. A preparation method of a water-based drilling fluid inhibitor, characterized in that, Comprising the following steps: S1. Add 0.05 mol - 1 mol of perfluoropolyether carboxylic acid into a three-necked flask equipped with a stirring device, a reflux condenser and a thermometer, and start stirring; S2. Mix 0.05 mol - 1 mol of thionyl chloride and 0.005 mol - 0.1 mol of pyridine, and slowly drop the mixture into the three-necked flask; S3. Heat the three-necked flask, raise the temperature to 80°C - 90°C, reflux for 3 h - 5 h, and then cool to room temperature; S4. Add 0.1 mol - 2 mol of hexamethylenediamine and ethyl acetate into the three-necked flask; S5. Reflux at 80°C - 85°C for 2 h - 3 h, distill off all the ethyl acetate, raise the temperature to 130°C and reflux for 24 h, cool to room temperature, add the product in the three-necked flask into a separatory funnel, and take the upper reddish-brown product as the target product.

6. The preparation method of the water-based drilling fluid inhibitor according to claim 5, characterized in that: In step S5, for the distillation and removal of ethyl acetate, a condenser in a roughly vertical direction is used to condense the vaporized ethyl acetate and reflux it back into the flask. After 2 - 3 h of reflux and reaction, connect the flask with a bent tube, and then connect a condenser in a roughly horizontal direction. At the same temperature, distill the ethyl acetate out of the flask.

7. The preparation method of the water-based drilling fluid inhibitor according to claim 5, characterized in that: The molar ratio between the components is: perfluoropolyether carboxylic acid: thionyl chloride: pyridine: hexamethylenediamine = 1:1:0.1:

2.

8. The preparation method of the water-based drilling fluid inhibitor according to claim 5, characterized in that: In the above preparation method, the amounts of the raw materials used are 1 mol of perfluoropolyether carboxylic acid, 1 mol of thionyl chloride, 0.1 mol of pyridine, and 2 mol of hexamethylenediamine.

9. The preparation method of the water-based drilling fluid inhibitor according to any one of claims 5-8, characterized in that: The molecular weight of the perfluoropolyether carboxylic acid is 1000 - 10000.

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