A high-temperature resistant functional inhibitor for drilling fluid and its production process

Abstract

The present invention belongs to the technical field of petrochemical engineering, and discloses a high-temperature resistant functional inhibitor for drilling fluid and its production process. By weight, the raw materials of the inhibitor include 16-20 parts of triethylenetetramine, 5-6 parts of dichloroethane, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 10-15 parts of pyridine, 1.5-2.5 parts of potassium chloride, and 3-5 parts of water; dichloroethane is slowly added dropwise to triethylenetetramine, and after the reaction is completed, pyridine and 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride are added to continue the reaction, and finally a potassium chloride solution is added and mixed evenly to obtain the high-temperature resistant functional inhibitor. The present invention has good shale inhibition performance and can be used normally under conditions above 200 °C, solving the problems of relatively high linear expansion rate and poor inhibition performance of traditional inhibitors.

Description

Technical Field

[0001] The present invention relates to the technical field of petrochemical engineering, and more particularly to a high-temperature resistant functional inhibitor for drilling fluid and its production process. Background Art

[0002] In recent years, with the gradual expansion of oil and gas development into deep wells and unconventional oil and gas wells, the demand for high-temperature resistant drilling fluid has been increasing. At present, the temperature resistance ability of the drilling fluid system is generally lower than 200°C. During the drilling process, major safety accidents such as wellbore collapse, sticking, lost circulation, and blowout often occur due to the failure of the drilling fluid, resulting in high drilling costs and easy formation damage, which has a significant impact on the development of deep-layer oil and gas. Wellbore instability is a serious problem existing in the process of oil and gas drilling and production. Wellbore instability will lead to a series of problems such as hole shrinkage, collapse and sticking, and hole enlargement, bringing great harm to the drilling engineering. When drilling, about 75% of the formations are shale formations, and 90% of the wellbore instability phenomena occur in shale formations. Shale formations are rich in water-absorbing clay minerals and have a significant nano-pore structure, which is extremely prone to hydration swelling and dispersion.

[0003] In a high-temperature and high-pressure environment, the performance of drilling fluid additives directly affects the safety and efficiency of drilling operations. Therefore, inhibitors in high-temperature resistant drilling fluid have become a research hotspot. At present, oil-based drilling fluid is mostly used in the drilling of shale gas horizontal wells in China. Although oil-based drilling fluid has excellent inhibition performance, its preparation cost is relatively high, there are environmental protection problems, and it is difficult to handle lost circulation. Once a lost circulation problem occurs, it will surely cause significant economic losses. Water-based drilling fluid has the advantages of low cost and environmental friendliness, but in the drilling of shale gas horizontal wells, it is difficult for conventional water-based drilling fluid to solve the problem of hydration swelling of shale gas shale, thus it is difficult to meet the engineering and technical needs of shale gas horizontal well exploration.

[0004] Common shale inhibitors in the prior art mainly include polymers, inorganic salts, asphalts, humic acids, etc., but these shale inhibitors all have some deficiencies, such as the rheology of drilling fluid is not easy to control at high temperatures, the molecular size is large and it cannot penetrate into the clay interlayers, toxicity problems, and it is difficult to meet the environmental protection indicators.

[0005] Therefore, aiming at the problem of wellbore instability caused by surface hydration of thick shale, developing a high-temperature resistant and pollution-free water-based inhibitor that can effectively inhibit shale hydration swelling has important practical significance. Summary of the Invention

[0006] In view of the above problems, the present invention provides a high-temperature resistant functional inhibitor for drilling fluid and its production process. It has good shale inhibition performance and can be used normally under conditions above 200 °C, solving the problems of relatively high linear expansion rate and poor inhibition performance of traditional inhibitors.

[0007] One of the purposes of the present invention is to provide a high-temperature resistant functional inhibitor for drilling fluid. By weight, the raw materials of the inhibitor include: 16 - 20 parts of triethylenetetramine; 5 - 6 parts of dichloroethane; 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride; 10 - 15 parts of pyridine; 1.5 - 2.5 parts of potassium chloride; 3 - 5 parts of water.

[0008] Preferably, by weight, the raw materials of the inhibitor include: 18 parts of triethylenetetramine; 6 parts of dichloroethane; 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride; 15 parts of pyridine; 2 parts of potassium chloride; 3 parts of water.

[0009] Another purpose of the present invention is to provide a preparation process for a high-temperature resistant functional inhibitor for drilling fluid, which includes the following steps:

[0010] (1) Weigh the raw materials;

[0011] (2) Add triethylenetetramine to the reaction vessel and slowly heat up to 65 - 90 °C;

[0012] (3) Under continuous stirring, slowly dropwise add dichloroethane to triethylenetetramine. After the addition is completed, continue stirring and reacting, stop heating, and cool to room temperature to obtain a reaction solution;

[0013] (4) Under anaerobic conditions, add pyridine to the reaction solution, cool it, and then add 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride for reaction, and then slowly heat up and continue reacting;

[0014] (5) After the reaction is completed, cool to room temperature, add potassium chloride solution, and mix evenly to obtain a high-temperature resistant functional inhibitor.

[0015] Preferably, in step (3), the time for the slow dropwise addition is 30 - 40 min, and the time for the stirring reaction is 15 min.

[0016] The beneficial effect of adopting the above technical means is that by slowly dropping dichloroethane into triethylenetetramine, triethylenetetramine is always in excess during the reaction process, so the resulting product is a polyamine compound rather than a quaternary ammonium salt compound.

[0017] Preferably, in step (4), the anaerobic condition is to introduce nitrogen for 20 - 30 min.

[0018] Preferably, in step (4), the cooling is to cool down to 0-5 °C and then add 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, and react for 30-40 min.

[0019] Preferably, in step (4), heat up to 20-40 °C and continue to react for 5-7 h.

[0020] The beneficial effects of adopting the above technical means are as follows: 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride is used to carry out a low-temperature polycondensation reaction with the excessive triethylenetetramine in the reaction solution to obtain hydrophilic groups such as quaternary ammonium salts and amide bonds, so that the inhibitor has good water solubility and dispersibility. Its quaternary ammonium salt group can carry out an ion exchange reaction with the inorganic cations in the crystal layers of bentonite minerals, tighten the crystal layers of bentonite minerals, play a role in fixing the crystal lattice, and inhibit the swelling and dispersion of bentonite; at the same time, the inhibitor forms ionic interaction and hydrogen bond interaction with bentonite, and forms a coating film on the surface of bentonite, which can prevent water molecules from entering the interlayer of bentonite minerals, thereby reducing the degree of hydration swelling of bentonite minerals. The linear expansion rate is significantly reduced, showing excellent anti-swelling effect.

[0021] Preferably, in step (5), the potassium chloride solution is prepared by adding potassium chloride to water and stirring to dissolve.

[0022] It can be seen from the above technical solutions that compared with the prior art, the beneficial effects obtained by the present invention are:

[0023] The polyamine molecule has multiple binding sites with clay, namely amino groups and hydroxyl groups. The amino group in the molecule can enter the interlayer of clay or adsorb on the surface of clay to form multi-point adsorption, firmly binding the clay. The hydroxyl group in the molecule can also enhance the interaction between the polyamine inhibitor and clay through hydrogen bonds.

[0024] The present invention has good thermal decomposition resistance and high temperature resistance. After high temperature heat treatment, the increase in the linear expansion rate of the inhibitor for bentonite minerals is small, and it still shows good anti-swelling effect, and can be applied to the drilling and exploitation of high temperature oil reservoirs.

[0025] The present invention obtains a polyamine compound by reacting triethylenetetramine with dichloroethane by controlling the equivalent amounts and feeding sequences of various raw materials, and adds a certain amount of potassium chloride to the reaction system to form a novel inhibitor composed of hydrophilic groups such as polyamine compounds, quaternary ammonium salts, and amide bonds and potassium chloride. The potassium chloride inhibitor ionizes potassium ions in water, and the potassium ions can enter the clay interlayers. By relying on the lattice fixation of the ions, the clay layers form a tight structure, reducing the clay layer spacing and inhibiting the internal hydration swelling of the clay. The polyamine inhibitor has multiple active amine points and has a long enough chain to bridge on the clay surface, forming a hydrophobic barrier on the clay surface. The two are used in combination, which not only inhibits the surface hydration of the clay but also inhibits the osmotic hydration of the clay, and the inhibition effect is significantly improved.

[0026] When the three are used in combination, the usage amount of potassium chloride is greatly reduced, avoiding environmental pollution caused by too high a concentration of potassium chloride, and it has good compatibility with other additives, is easy to regulate, and is convenient to use;

[0027] The preparation method is simple, the raw material cost is low, and it is convenient for large-scale production. Specific embodiments

[0028] 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. Example 1

[0029] A preparation process for a high-temperature resistant functional inhibitor for drilling fluid includes the following steps:

[0030] (1) Weigh 16 parts of triethylenetetramine, 5 parts of dichloroethane, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 10 parts of pyridine, 1.5 parts of potassium chloride, and 3 parts of water;

[0031] (2) Add triethylenetetramine to the reaction vessel and slowly heat up to 65-90 °C;

[0032] (3) Under continuous stirring conditions, slowly dropwise add dichloroethane to triethylenetetramine for 40 min. After the addition is complete, continue stirring and reacting for 15 min, stop heating, and cool to room temperature to obtain a reaction solution;

[0033] (4) Introduce nitrogen for 30 min, add pyridine to the reaction solution, cool to 0-5 °C, then add 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, react for 30 min, and then slowly rise to 30 °C and continue reacting for 6 h;

[0034] After the reaction is completed, cool it to room temperature, add potassium chloride to water, stir to dissolve, add it to the reaction mixture, and mix evenly to obtain a high-temperature resistant functional inhibitor. Example 2

[0035] A preparation process of a high-temperature resistant functional inhibitor for drilling fluid, which is different from Example 1 in that:

[0036] (1) Weigh 17 parts of triethylenetetramine, 5 parts of dichloroethane, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 12 parts of pyridine, 2.5 parts of potassium chloride, and 3 parts of water. Example 3

[0037] A preparation process of a high-temperature resistant functional inhibitor for drilling fluid, which is different from Example 1 in that:

[0038] (1) Weigh 20 parts of triethylenetetramine, 6 parts of dichloroethane, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 14 parts of pyridine, 1.5 parts of potassium chloride, and 3 parts of water. Example 4

[0039] A preparation process of a high-temperature resistant functional inhibitor for drilling fluid, which is different from Example 1 in that:

[0040] (1) Weigh 18 parts of triethylenetetramine, 6 parts of dichloroethane, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 15 parts of pyridine, 2 parts of potassium chloride, and 3 parts of water.

[0041] Comparative Example 1

[0042] A preparation process of a drilling fluid inhibitor, which is different from Example 1 in that:

[0043] (1) Weigh 16 parts of triethylenetetramine, 5 parts of dichloroethane, 1.5 parts of potassium chloride, and 3 parts of water;

[0044] (2) Add triethylenetetramine to the reaction vessel, and slowly heat it to 65 - 90 °C;

[0045] (3) Under continuous stirring conditions, slowly add dichloroethane to triethylenetetramine dropwise for 40 min, continue stirring and reacting for 15 min after the addition is completed, stop heating, and cool to room temperature to obtain a reaction solution;

[0046] (4) Add potassium chloride to water, stir to dissolve, add it to the reaction mixture, and mix evenly to obtain inhibitor I.

[0047] Comparative Example 2

[0048] A preparation process of a drilling fluid inhibitor, which is different from Example 1 in that:

[0049] (1) Weigh 16 parts of triethylenetetramine, 30 parts of 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, 10 parts of pyridine, 1.5 parts of potassium chloride, and 3 parts of water.

[0050] (2) Add triethylenetetramine to the reaction vessel, introduce nitrogen for 30 min, add pyridine to the reaction solution, cool to 0 - 5 °C, then add 2,5-bis(imine-1-methylimidazole) terephthaloyl chloride, react for 30 min, and then slowly raise the temperature to 30 °C and continue to react for 6 h.

[0051] (3) After the reaction is completed, cool to room temperature, dissolve potassium chloride in water by stirring, add it to the reaction mixture, and mix evenly to obtain Inhibitor II.

[0052] Experiment 1: Linear expansion rate test of inhibitors

[0053] Conduct a linear expansion experiment on the high-temperature resistant functional inhibitors prepared in Examples 1 - 4 of the present invention: Weigh 5 g of bentonite, pour it into the sleeve, compact it under a pressure of 10 MPa for 5 min, place a layer of filter paper on the compacted bentonite, embed the sleeve in the dilatometer, and add purified water, the high-temperature resistant functional inhibitors prepared in Examples 1 - 4, and the inhibitors prepared in Comparative Examples 1 - 2 respectively. Record the swelling amount of bentonite after 1 h and 16 h, calculate the linear expansion rate, and evaluate the inhibitory performance of the inhibitors. Generally speaking, the higher the linear expansion rate, the worse the inhibitory performance, and vice versa. The test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] As can be seen from the above table, when treating bentonite with purified water, the linear expansion rate of bentonite is as high as 43.60%. When using the high-temperature resistant functional inhibitors prepared in Examples 1 - 4 of the present invention, the linear expansion rate of bentonite is reduced to a minimum of 7.06%, effectively reducing the linear expansion rate of bentonite, and the inhibitory performance is significantly stronger than that of the inhibitors in the comparative examples.

[0057] Experiment 2: Chip rolling recovery inhibition test of inhibitors:

[0058] Conduct a chip recovery experiment on the inhibitors in Examples 1 - 4 and Comparative Examples 1 - 2 of the present invention. Generally speaking, the higher the chip recovery rate, the better the inhibitory performance, and vice versa. Use sandstone as the rock sample, and the test results are shown in Table 2.

[0059] Table 2

[0060]

[0061] According to the above data, the high-temperature resistant functional inhibitor obtained by the present invention has good shale stabilizing performance and temperature resistance. When the dosage is 1 wt.%, the shale rolling recovery rate is above 95%, and the temperature resistance reaches 200 °C.

[0062] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can 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 disclosed herein.

Claims

1. A high-temperature resistant functional inhibitor for drilling fluid, characterized in that, By weight parts, the raw materials of the inhibitor include: 16 - 20 parts of triethylenetetramine; 5 - 6 parts of dichloroethane; 30 parts of 2,5 - bis(imine - 1 - methylimidazole) terephthaloyl chloride; 10 - 15 parts of pyridine; 1.5 - 2.5 parts of potassium chloride; 3 - 5 parts of water; The preparation process of the inhibitor includes the following steps: (1) Weigh the raw materials; (2) Add triethylenetetramine to the reaction vessel and slowly heat up to 65 - 90 °C; (3) Under continuous stirring conditions, slowly dropwise add dichloroethane to triethylenetetramine. After the dropwise addition is completed, continue stirring and reacting, stop heating, and cool to room temperature to obtain a reaction solution; (4) Under anaerobic conditions, add pyridine to the reaction solution. After cooling, add 2,5 - bis(imine - 1 - methylimidazole) terephthaloyl chloride for reaction, and then slowly heat up and continue the reaction; (5) After the reaction is completed, cool to room temperature, add a potassium chloride solution, and mix evenly to obtain a high - temperature - resistant functional inhibitor.

2. The high-temperature resistant functional inhibitor for drilling fluid according to claim 1, wherein By weight parts, the raw materials of the inhibitor include: 18 parts of triethylenetetramine; 6 parts of dichloroethane; 30 parts of 2,5 - bis(imine - 1 - methylimidazole) terephthaloyl chloride; 15 parts of pyridine; 2 parts of potassium chloride; 3 parts of water.

3. The preparation process of a high-temperature resistant functional inhibitor for drilling fluid according to claim 1, characterized in that, In step (3), the time for the slow dropwise addition is 30 - 40 min, and the time for the stirring reaction is 15 min.

4. The preparation process of a high-temperature resistant functional inhibitor for drilling fluid according to claim 1, characterized in that, In step (4), the anaerobic condition is to introduce nitrogen for 20 - 30 min.

5. The preparation process of a high-temperature resistant functional inhibitor for drilling fluid according to claim 1, characterized in that, In step (4), the cooling is to cool down to 0 - 5 °C and then add 2,5 - bis(imine - 1 - methylimidazole) terephthaloyl chloride, and react for 30 - 40 min.

6. The preparation process of a high-temperature resistant functional inhibitor for drilling fluid according to claim 1, characterized in that, In step (4), heat up to 20 - 40 °C and continue the reaction for 5 - 7 h.

7. The preparation process of a high-temperature resistant functional inhibitor for drilling fluid according to claim 1, characterized in that, In step (5), the potassium chloride solution is prepared by adding potassium chloride to water and stirring until dissolved.

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