Mannich type modified diethylenetriamine calcium lignosulphonate-based filtrate reducer and preparation method thereof

Abstract

The invention provides a Mannich type modified diethylenetriamine calcium lignosulphonate-based filtrate reducer, which is characterized in that the Mannich type modified diethylenetriamine calcium lignosulphonate-based filtrate reducer is prepared by reacting calcium lignosulphonate, formaldehyde, diethylenetriamine and anhydrous sodium sulfite. The filtrate reducer can resist the temperature of 180 DEG C, the calcium resistance of the filtrate reducer is greatly improved and reaches 10000 mg / L compared with that of a conventional filtrate reducer, and the filtrate reducer is good in compatibility with various water-based drilling fluids, convenient to use and capable of boosting technical progress of anti-pollution drilling fluids and has important application value.

Description

Technical Field

[0001] The present invention relates to the technical field of drilling fluids, and in particular to a Mannich-type modified calcium lignosulfonate-based fluid loss reducer derived from diethylenetriamine and its preparation method. Background Art

[0002] With the continuous exploration of oil and gas resources towards deep formations, the exploration targets are gradually expanding rapidly towards deep complex formations with high temperature and high salinity. The encounters with salt gypsum layers, thick gypsum layers, calcium and magnesium-containing or calcium salt formations are increasing. The superposition of salt calcium and acid radical pollution and the high-temperature effect lead to the rapid deterioration of the performance of the drilling fluid system. In severe cases, there is a sharp thickening, causing the drilling fluid to lose fluidity and affecting downhole safety. For example, in the Hubeizhai area of Dongpu and the third member of the Shahejie Formation in the Liutun Sag, the calcium ion content can reach 2000 - 4000 mg / L when drilling through gypsum salt rocks; in the Santamu Formation and the Ying Mountain Formation in the northwest, there is acid radical pollution. For example, at 6986 meters in Well Shunnan 16, the CO2 content in the gas logging value is 50%, the funnel viscosity is 280 s, the dynamic shear force is 60 Pa, the static shear force is 30 Pa / 32 Pa, and all the medium-pressure filtration loss is filtered out. At 6639.81 meters in Well Shunnanpeng 1, there is a high-pressure brine invasion, and more than 50 cubic meters of contaminated mud is discharged, and all the medium-pressure filtration loss occurs in the contaminated mud. In the southwest, in Well Mashen 1 and Well Feng 1 in the Qinjiamiao Formation, high-temperature thickening has occurred many times, and the drilling fluid needs to be replaced. In addition, for ultra-deep well cementing, the "liner hanger + tie-back casing" method is mostly used, and the cementing working fluid contaminates the drilling fluid many times, resulting in a large amount of contaminated mud and causing the drilling fluid to solidify at high temperature. The existing technical means (except for a large amount of new mud preparation and replacement) cannot effectively solve the problem of cement slurry pollution. Therefore, higher requirements and challenges are put forward for the temperature resistance and salt calcium resistance of the drilling fluid.

[0003] As one of the core key treatment agents for high-temperature-resistant drilling fluids, the fluid loss reducer plays a crucial role in wellbore stability and protecting oil and gas reservoirs. The temperature and calcium resistance of the fluid loss reducer are crucial for the performance of the drilling fluid in high-temperature and high-calcium formations and safe drilling. There are mainly two categories of fluid loss reducers: polymer fluid loss reducers that play a viscosity-increasing role and phenolic resin-based fluid loss reducers that play a cross-linking and pore-blocking role. There have been many studies on polymer-based fluid loss reducers, and polymer fluid loss reducers with a temperature resistance of 150 °C and a calcium resistance of 30000 mg / L have been maturely applied. However, the development of synthetic resin-based temperature and calcium-resistant fluid loss reducers has been relatively slow. The sulfomethylated phenolic resin fluid loss reducer (SMP) is formed by sulfonation and polycondensation reactions of phenol, formaldehyde, and a sulfonating agent. Currently, it is the most widely used and effective high-temperature-resistant filtration loss reduction product, with a temperature resistance greater than 150 °C, but a calcium resistance less than 1000 mg / L, facing the problem of not meeting on-site requirements. There is an urgent need to develop a new type of temperature and calcium-resistant synthetic resin-based fluid loss reducer. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a Mannich-type modified calcium lignosulfonate-based fluid loss reducer derived from diethylenetriamine, and the above-mentioned fluid loss reducer provided by the present invention has good high-temperature fluid loss reduction performance.

[0005] The present invention provides a Mannich-type modified calcium lignosulfonate-based fluid loss reducer, which is characterized in that it is prepared by reacting calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite.

[0006] Preferably, the mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 24-26:57-58:8-9:1-1.1.

[0007] The present invention provides a preparation method of a Mannich-type modified calcium lignosulfonate-based fluid loss reducer, comprising the following steps:

[0008] Mix calcium lignosulfonate and formaldehyde, add anhydrous sodium sulfite, then add diethylenetriamine after heating, carry out a heating reflux reaction, and dry to obtain the product.

[0009] Preferably, the heating-up is specifically to heat up to 70°C ± 2°C and maintain for 30 min.

[0010] Preferably, the heating reflux reaction is specifically at 102-105°C for 4 h.

[0011] Preferably, the formaldehyde is a formaldehyde solution with a mass percentage of 37%.

[0012] Preferably, the drying is specifically drying at 105°C for 4 h.

[0013] Preferably, the mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 24-26:57-58:8-9:1-1.1.

[0014] The present invention provides a drilling fluid treatment agent, comprising the Mannich-type modified calcium lignosulfonate-based fluid loss reducer described in any one of the above technical solutions or the Mannich-type modified calcium lignosulfonate-based fluid loss reducer prepared by the preparation method described in any one of the above technical solutions.

[0015] Preferably, the addition amount of the Mannich-type modified calcium lignosulfonate-based fluid loss reducer is 3%-5%.

[0016] Compared with the prior art, the present invention provides a Mannich-type modified calcium lignosulfonate-based fluid loss reducer, which is characterized in that it is prepared by reacting calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite. The fluid loss reducer of the present invention has a temperature resistance of 180°C, greatly improves the calcium resistance compared with conventional fluid loss reducers, reaching 10,000 mg / L, has good compatibility with various water-based drilling fluids, is easy to use, promotes the progress of anti-pollution drilling fluid technology, and has important application value. Brief Description of the Drawings

[0017] Figure 1 is the IR spectrum;

[0018] Figure 2 is the molecular weight distribution diagram.. Detailed Embodiments

[0019] The present invention provides a Mannich-type modified calcium lignosulfonate-based filtrate reducer and its preparation method. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they all fall within the scope of protection of the present invention. The method and application of the present invention have been described through preferred embodiments, and those skilled in the art can obviously make changes or appropriate modifications and combinations to the methods and applications in this article without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0020] In this application, the term "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0021] In this application, "at least one" means one or more, and "a plurality" means two or more. "At least one of the following" or its similar expressions refer to any combination of these items, including any combination of single items or plural items.

[0022] It should be understood that in various embodiments of this application, the magnitude of the serial numbers of the above processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of this application.

[0023] The numerical ranges and parameters involved in the present invention have presented the relevant numerical values in the specific embodiments as precisely as possible. However, any numerical value inevitably contains standard deviations caused by individual testing methods. Therefore, unless otherwise clearly stated, it should be understood that all numerical ranges or specific data used in this disclosure may have certain reasonable deviations within a certain range, for example: within 1% or 0.5%.

[0024] Some cases are recorded in the embodiments and comparative examples of the present invention, and some implementation manners of the present invention are shown in the embodiments. However, this does not mean that the effects of the present invention can only be achieved in these cases.

[0025] Lignin is a complex macromolecular compound present in the xylem of most terrestrial plants and ranks second only to cellulose in natural reserves. Calcium lignosulfonate (abbreviated as calcium lignosulfonate) is a multi-component macromolecular polymer anionic surfactant, with an appearance of light yellow to dark brown powder, a slightly aromatic odor, and a molecular weight generally between 800 and 10,000. It has strong dispersibility, adhesiveness, and chelating properties. It is usually obtained from the cooking waste liquor of acid pulping (or called sulfite pulping) and is spray-dried. Calcium lignosulfonate retains the natural macromolecular structure of lignin, is rich in groups such as benzene rings, hydroxyl groups, and phenolic hydroxyl groups, has strong heat resistance, high reactivity, and is particularly insensitive to calcium ions, making it possible to prepare calcium-resistant drilling fluid treatment agents. It is commonly used as a drilling fluid dispersant in the oil and gas field industry and has a certain effect of reducing the viscosity of drilling fluid.

[0026] In the present invention, lignin is modified to prepare a calcium-resistant lignin-based filtrate reducer, which can not only reduce the discharge of pulping pollutants but also achieve resource recycling, having social and economic benefits.

[0027] The present invention provides a Mannich-type modified diethylenetriamine calcium lignosulfonate-based filtrate reducer, which is prepared by reacting calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite.

[0028] According to the present invention, the mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 24-26:57-58:8-9:1-1.1.

[0029] According to the present invention, the preferred mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 25:57.11:8.37:1.04.

[0030] Among them, formaldehyde is preferably a formaldehyde solution with a mass percentage of 37%.

[0031] The present invention creatively uses diethylenetriamine as a raw material for the filtrate reducer, and its performance is significantly better than that of tetraethylenepentamine or triethylenetetramine-modified lignin.

[0032] Calcium lignosulfonate, lignosulfonic acid, calcium salt, CAS No. 8061-52-7, the molecular structure ( Figure 1 ) is rich in benzene rings, and the ortho and para positions of phenolic hydroxyl groups have high reactivity. It can be used as an ideal substitute for phenol. Mannich modification is carried out on it with diethylenetriamine, and then a diethylenetriamine-modified calcium lignosulfonate-based filtrate reducer is synthesized, which can be cyclized into a network three-dimensional structure, ensuring the anti-temperature performance of the product while improving the anti-calcium performance. Sulfonation is carried out at 70 °C, and amination is carried out at 102-105 °C.

[0033] The principle of Mannich modification of calcium lignosulfonate with diethylenetriamine can be expressed by the following formula: Among them, formula (I) is the molecular structure of calcium lignosulfonate; formula (II) is the modification reaction formula;

[0034]

[0035]

[0036] In the above formula, n has a distribution range, and the appropriate raw material ratio and reaction conditions can be adjusted according to the usage requirements to achieve the purpose of controlling n, and it is preferably 3-4.

[0037] Wang Zhonghua, "New Theory of Drilling Fluids and Treating Agents", P62. When the relative molecular mass is about 3000, it is a thinner, and when the relative molecular mass is 5×10 4 ~20×10 4 , the filtration loss reducing effect is obvious. The molecular weight of the filtration loss reducer synthesized in Example 1 was tested by gel chromatography analysis. The weight average molecular weight MW was 10465, meeting the requirements of the high temperature resistant filtration loss reducer. Figure 2 It is the molecular weight distribution diagram.

[0038] The IR spectrum of the Mannich type modified diethylenetriamine calcium lignosulfonate based filtration loss reducer of the present invention was determined using a 5DX Fourier transform infrared spectrometer produced by Nicolet Company of the United States, with a NaCl salt window and a spectral collection range of 400-4000 cm-1. Figure 1 It is the IR spectrum diagram. It was found through experiments that the stretching vibration peak of the aldehyde group in the reactant molecules could no longer be seen in the IR spectrum, indicating that the Mannich reaction occurred among the amine, phenol, and aldehyde according to the equation.

[0039] Based on the comprehensive infrared spectrum and gel chromatography analysis, the synthesized product is consistent with the design. It can be calculated that the n value of formula (II) is 3-4.

[0040] The present invention provides a preparation method of a Mannich type modified diethylenetriamine calcium lignosulfonate based filtration loss reducer, including the following steps:

[0041] Mix calcium lignosulfonate and formaldehyde, add anhydrous sodium sulfite, heat up and then add diethylenetriamine, heat under reflux for reaction, and dry to obtain.

[0042] In the present invention, calcium lignosulfonate and formaldehyde are mixed and anhydrous sodium sulfite is added; specifically preferably:

[0043] Add calcium lignosulfonate and formaldehyde solution to a three-necked flask equipped with an electric stirrer, a thermometer, a constant pressure dropping funnel, and a reflux condenser. After stirring evenly, add anhydrous sodium sulfite.

[0044] In some preferred embodiments, the formaldehyde is a formaldehyde solution with a mass percentage of 37%.

[0045] In some preferred embodiments, the mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite and diethylenetriamine is 24 - 26:57 - 58:8 - 9:1 - 1.1.

[0046] In some preferred embodiments, the mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite and diethylenetriamine is 25:57.11:8.37:1.04.

[0047] The present invention does not limit the specific manner of the above stirring, and those well-known to those skilled in the art can be used.

[0048] After adding anhydrous sodium sulfite, the temperature is raised and then diethylenetriamine is added, and heating and reflux reaction are carried out.

[0049] The temperature increase in the present invention is specifically to increase the temperature to 70°C ± 2°C and maintain it for 30 min.

[0050] Specifically, the heating and reflux reaction is specifically at 102 - 105°C for 4 h of reflux reaction.

[0051] The reaction solution is poured into a shallow bottom tray and dried in an oven at 105°C for 4 h to obtain a dark brown solid, which is pulverized to obtain a Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer.

[0052] The present invention provides a drilling fluid treatment agent, including the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer described in any one of the above technical solutions or the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer prepared by the preparation method described in any one of the above technical solutions.

[0053] The present invention has clearly described the above specific preparation method, and will not be elaborated herein.

[0054] The preferred addition amount of the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer in the present invention is 3% - 5%.

[0055] Within the above range, the filtrate reduction performance of the drilling fluid system is good. Considering the comprehensive use effect and use cost, the present invention recommends an addition amount of 3% - 5%.

[0056] The present invention provides a Mannich-type modified calcium lignosulfonate-based filtrate reducer, which is characterized in that it is prepared by reacting calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite. The filtrate reducer of the present invention can withstand a temperature of 180°C, and its calcium resistance is greatly improved compared with conventional filtrate reducers, reaching 10,000 mg / L. It has good compatibility with various water-based drilling fluids, is easy to use, promotes the progress of anti-pollution drilling fluid technology, and has important application value.

[0057] To further illustrate the present invention, the following is a detailed description of a Mannich-type modified calcium lignosulfonate-based filtrate reducer provided by the present invention and its preparation method in combination with examples.

[0058] For the agents in the examples and comparative examples, calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite are all industrial products, and it is only necessary to meet the relevant national and industrial standards.

[0059] Example 1

[0060] Add 25 g of calcium lignosulfonate and 57.11 g of a 37% by mass formaldehyde solution to a three-necked flask equipped with an electric stirrer, a thermometer, a constant pressure dropping funnel, and a reflux condenser. After stirring evenly, add 8.37 g of anhydrous sodium sulfite, raise the temperature to 70°C, add 1.04 of diethylenetriamine after 30 min, slowly heat to 102 - 105°C, and carry out a reflux reaction for 4 h. After the reaction is completed, pour the reaction solution into a shallow bottom tray and dry it in an oven at 105°C for 4 h to obtain a dark brown solid. After pulverization, it is a Mannich-type modified calcium lignosulfonate-based filtrate reducer.

[0061] Comparative Example 1

[0062] Add 25 g of calcium lignosulfonate and 57.11 g of a 37% by mass formaldehyde solution to a three-necked flask equipped with an electric stirrer, a thermometer, a constant pressure dropping funnel, and a reflux condenser. After stirring evenly, add 8.37 g of anhydrous sodium sulfite, raise the temperature to 70°C, add 2.25 g of triethylenetetramine with a mass percentage of 65% after 30 min, slowly heat to 102 - 105°C, and carry out a reflux reaction for 4 h. After the reaction is completed, pour the reaction solution into a shallow bottom tray and dry it in an oven at 105°C for 4 h to obtain a dark brown solid. After pulverization, it is a Mannich-type modified calcium lignosulfonate-based filtrate reducer with triethylenetetramine.

[0063] Comparative Example 2

[0064] In a three-necked flask equipped with an electric stirrer, a thermometer, a constant-pressure dropping funnel, and a reflux condenser, add 25 g of calcium lignosulfonate and 57.11 g of a formaldehyde solution with a mass percentage of 37%. After stirring evenly, add 8.37 g of anhydrous sodium sulfite, heat up to 70 °C, and after 30 min, add 1.99 g of tetraethylenepentamine with a mass percentage of 95%. Slowly heat to 102 - 105 °C and carry out a reflux reaction for 4 h. After the reaction is completed, pour the reaction solution into a shallow-bottomed tray and dry it in an oven at 105 °C for 4 h to obtain a dark brown solid. After pulverization, it is a Mannich-type modified tetraethylenepentamine calcium lignosulfonate filtrate reducer.

[0065] Example 4

[0066] Weigh 300.0 mL of the test slurry in a 400 mL high-speed stirring cup, then add 6 g (mass-to-volume ratio of 2%) of the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer prepared in Example 1, place it in a high-temperature roller furnace at 180 °C for aging for 16 h, and conduct the test according to the high-temperature and high-pressure (HTHP) filtration loss test procedure in Section 7.3 of "Oil and Gas Industry - Drilling Fluid Field Testing - Part 1: Water-Based Drilling Fluids" (GB / T 16783.1 - 2014). The high-temperature and high-pressure filtration loss volume is 40 mL.

[0067] Example 5

[0068] Weigh 300.0 mL of the test slurry in a 400 mL high-speed stirring cup, then add 9 g (mass-to-volume ratio of 3%) of the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer prepared in Example 1, place it in a high-temperature roller furnace at 180 °C for aging for 16 h, and conduct the test according to the high-temperature and high-pressure (HTHP) filtration loss test procedure in Section 7.3 of "Oil and Gas Industry - Drilling Fluid Field Testing - Part 1: Water-Based Drilling Fluids" (GB / T 16783.1 - 2014). The high-temperature and high-pressure filtration loss volume is 20 mL.

[0069] Example 6

[0070] Weigh 300.0 mL of the test slurry in a 400 mL high-speed stirring cup, then add 12 g (mass-to-volume ratio of 4%) of the Mannich-type modified diethylenetriamine calcium lignosulfonate filtrate reducer prepared in Example 1, place it in a high-temperature roller furnace at 180 °C for aging for 16 h, and conduct the test according to the high-temperature and high-pressure (HTHP) filtration loss test procedure in Section 7.3 of "Oil and Gas Industry - Drilling Fluid Field Testing - Part 1: Water-Based Drilling Fluids" (GB / T 16783.1 - 2014). The high-temperature and high-pressure filtration loss volume is 16 mL.

[0071] Example 7

[0072] Weigh 300.0 mL of the test slurry in a 400 mL high - speed stirring cup, then add 15 g of the Mannich - type modified calcium lignosulfonate filtrate reducer prepared in Example 1 (mass - volume ratio 5%). Place it in a high - temperature roller furnace at 180 °C for 16 h, and conduct the test according to the high - temperature and high - pressure (HTHP) filtrate loss test procedure in Section 7.3 of "Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water - based drilling fluids" (GB / T 16783.1 - 2014). The high - temperature and high - pressure filtrate loss is 10 mL.

[0073] Comparative Example 3

[0074] Weigh 300.0 mL of the test slurry in a 400 mL high - speed stirring cup, and conduct the test according to the high - temperature and high - pressure (HTHP) filtrate loss test procedure in Section 7.3 of "Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water - based drilling fluids" (GB / T 16783.1 - 2014). The high - temperature and high - pressure filtrate loss is 70 mL.

[0075] Comparative Example 4

[0076] Weigh 300.0 mL of the test slurry in a 400 mL high - speed stirring cup, then add 15 g of lignin, and conduct the test according to the high - temperature and high - pressure (HTHP) filtrate loss test procedure in Section 7.3 of "Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water - based drilling fluids" (GB / T 16783.1 - 2014). The 5 - minute high - temperature and high - pressure filtrate loss is 100 mL.

[0077] Comparative Example 5

[0078] Weigh 300.0 mL of the test slurry in a 400 mL high - speed stirring cup, then add 15 g of triethylenetetramine, and conduct the test according to the 7.3 high - temperature and high - pressure (HTHP) filtrate loss test procedure in "Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water - based drilling fluids" (GB / T 16783.1 - 2014). The 5 - minute high - temperature and high - pressure filtrate loss is 96 mL.

[0079] Comparative Example 6

[0080] Weigh 300.0 mL of the test slurry in a 400 mL high - speed stirring cup, then add 15 g of the triethylenetetramine - modified lignin of Comparative Example 1, and conduct the test according to the 7.3 high - temperature and high - pressure (HTHP) filtrate loss test procedure in "Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water - based drilling fluids" (GB / T 16783.1 - 2014). The high - temperature and high - pressure filtrate loss is 84 mL.

[0081] Comparative Example 7

[0082] Weigh 300.0 mL of the test slurry in a 400 mL high-speed stirrer cup, then add 15 g of tetraethylenepentamine-modified lignin in Comparative Example 2. Conduct the test according to the high-temperature and high-pressure (HTHP) filtration loss test procedure in "Petroleum and Natural Gas Industries - Drilling Fluid Field Testing - Part 1: Water-Based Drilling Fluids" (GB / T 16783.1 - 2014). The high-temperature and high-pressure filtration loss volume is 92 mL.

[0083] The measured high-temperature and high-pressure filtration loss volume data of Examples 4 - 6 and Comparative Examples 1 - 5 are summarized in the table.

[0084] Table 2 Experimental Results of Examples 4 - 7 and Comparative Examples 1 - 5

[0085] Product Addition amount / % High temperature and high pressure fluid loss volume / mL Example 4 Diethylenetriamine modified lignin 2 40.4 Example 5 Diethylenetriamine modified lignin 3 20.8 Example 6 Diethylenetriamine modified lignin 4 16.0 Example 7 Diethylenetriamine modified lignin 5 10.2 Comparative Example 3 Base slurry 0 64.8 Comparative Example 4 Lignin 5 5 min 100 Comparative Example 5 Diethylenetriamine 5 5 min 96.2 Comparative Example 6 Triethylenetetramine modified lignin 5 50.0 Comparative Example 7 Tetraethylenepentamine modified lignin 5 58.6

[0086] It can be seen from the comparison between Example 7 and Comparative Example 3 that after adding diethylenetriamine-modified lignin to the base slurry, the high-temperature and high-pressure filtration loss volume decreases, indicating that diethylenetriamine-modified lignin has good high-temperature filtration loss reduction performance.

[0087] It can be known from the comparison between Comparative Example 3 and Comparative Example 4 that lignin itself has no reducing effect on the filtration loss performance of the drilling fluid. Lignin is a natural macromolecular polymer and has a dispersing effect on clay. It is often used as a drilling fluid dispersant in oil and gas field development. When added alone, the filtration loss volume increases. It can be seen from the comparison between Example 7 and Comparative Example 2 that the modification of lignin is the key to improving the filtration loss reduction performance of lignin.

[0088] It can be known from the comparison between Comparative Example 5 and Comparative Example 3 that using triethylenetriamine alone has no effect on the filtration loss performance of the drilling fluid. On the contrary, the amine group has a flocculating effect on clay, causing the destruction of the clay colloid stability and increasing the filtration loss volume. It can be seen from the comparison between Example 7 and Comparative Examples 4 and 5 that the performance of diethylenetriamine-modified lignin is not a simple superposition of lignin and diethylenetriamine. The polymerization reaction between diethylenetriamine and lignin promotes the improvement of the performance of diethylenetriamine-modified lignin.

[0089] It can be seen from the comparison between Example 7 and Comparative Examples 6 and 7 that the chain length of the enamine used for modification also has a great influence on the filtration loss reduction performance of lignin. With the same addition amount of 5% of the drilling fluid, the filtration loss reduction performance of diethylenetriamine-modified lignin is significantly better than that of tetraethylenepentamine- or triethylenetetramine-modified lignin.

[0090] It can be seen from the comparison among Examples 4 - 7 that the larger the addition amount of the diethylenetriamine-modified lignin filtration loss reducer, the better the filtration loss reduction performance of the drilling fluid system. Considering the comprehensive use effect and use cost, the recommended addition amount is 3% - 5%.

[0091] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A Mannich-type modified calcium lignosulfonate-based fluid loss reducer, characterized in that, It is prepared by reacting calcium lignosulfonate, formaldehyde, diethylenetriamine, and anhydrous sodium sulfite.

2. The Mannich-type modified calcium lignosulfonate-based fluid loss reducer according to claim 1, wherein The mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 24 - 26:57 - 58:8 - 9:1 - 1.

1.

3. A preparation method of a Mannich-type modified calcium lignosulfonate-based fluid loss reducer with diethylenetriamine, characterized in that, It includes the following steps: Mix calcium lignosulfonate and formaldehyde, add anhydrous sodium sulfite, then add diethylenetriamine after raising the temperature, carry out heating reflux reaction, and dry to obtain it.

4. The preparation method according to claim 3, characterized in that, The specific temperature increase is to raise the temperature to 70°C ± 2°C and maintain it for 30 min.

5. The preparation method according to claim 3, characterized in that, The specific heating reflux reaction is at 102 - 105°C for 4 h of reflux reaction.

6. The preparation method according to claim 3, characterized in that, The formaldehyde is a formaldehyde solution with a mass percentage of 37%.

7. The preparation method according to claim 3, characterized in that, The specific drying is drying at 105°C for 4 h.

8. The preparation method according to claim 3, characterized in that, The mass ratio of calcium lignosulfonate, formaldehyde, anhydrous sodium sulfite, and diethylenetriamine is 24 - 26:57 - 58:8 - 9:1 - 1.

1.

9. A drilling fluid treatment agent, characterized in that, It includes the Mannich - type modified diethylenetriamine calcium lignosulfonate - based filtration reducer described in any one of claims 1 - 2 or the Mannich - type modified diethylenetriamine calcium lignosulfonate - based filtration reducer prepared by the preparation method described in any one of claims 3 - 8.

10. The drilling fluid treating agent according to claim 9, wherein, The addition amount of the Mannich - type modified diethylenetriamine calcium lignosulfonate - based filtration reducer is 3% - 5%.

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