Asphalt inhibitor for water-based drilling fluid and preparation method thereof

Abstract

The invention provides an asphalt inhibitor for water-based drilling fluid and a preparation method of the asphalt inhibitor, and relates to the technical field of oilfield chemistry. The asphalt inhibitor is obtained by ammoniating polyethylene glycol, polypropylene glycol or ethylene glycol / propylene glycol copolymer at high temperature and high pressure. The finally prepared inhibitor has a good inhibition effect on asphaltene invading into water-based drilling fluid and can be applied to well drilling of oil sand-containing and asphalt-containing stratums or heavy oil stratums so as to avoid asphalt pollution.

Description

Technical Field

[0001] The present invention belongs to the field of chemical technology of oilfields, and specifically relates to a bituminous inhibitor for water-based drilling fluid and a preparation method thereof. Background Art

[0002] In recent years, my country has often encountered complex asphalt formations with strong heterogeneity and activity during the oil and gas exploration and development in overseas regions such as the Middle East and Canada. The distribution of asphalt formations is highly random and difficult to predict effectively. Asphalt in active formations has plastic creep and paste-like flow characteristics, and has strong adhesion. After invading the wellbore, it will seriously deteriorate the performance of the drilling fluid, and easily cause complex problems such as screen sticking, foaming, and well leakage, especially the problem of stuck drill. The frequent occurrence of these complex situations forces the site to frequently stop drilling, and the accumulated asphalt has to be removed or the foam controlled, which wastes production operation time and even leads to side drilling, premature completion of drilling or abandonment of the well, which seriously affects drilling safety and causes huge economic losses.

[0003] Asphalt is a dark brown mixture of hydrocarbons of different molecular weights and their non-metallic derivatives. The chemical composition of asphalt is relatively complex, and it is usually divided into asphaltenes, colloids, aromatic hydrocarbons and saturated hydrocarbons according to the physicochemical properties of asphalt components. According to its source, asphalt can be divided into natural asphalt, petroleum asphalt and coal tar asphalt. Natural asphalt mainly refers to the original asphalt stored in the stratum in the natural state or gathered on the surface of the earth's crust; the research object of this patent mainly refers to the formation asphalt that invades the wellbore during oil and gas drilling. Statistical analysis shows that at present, both hard block hard asphalt (carbonaceous asphalt, coal tar, etc., softening point 95~120°C), viscoelastic soft asphalt (viscous flow asphalt with low softening point, asphaltene deposited in the wellbore, etc., softening point 35~95°C) and asphalt thick oil (softening point <50°C) have been drilled. Formation asphalt can be stored in cracks or pores in a dispersed or continuous state, or it can be a large asphalt layer of a certain thickness. After asphalt invades the drilling fluid, it is easy to deteriorate the rheological properties and lubrication properties of the drilling fluid and reduce the density of the drilling fluid; as the softening point of asphalt decreases, the solubility rate of asphalt in diesel gradually increases; hard asphalt with a higher softening point has relatively little effect on the density and rheology of the drilling fluid, and can be easily screened out in time by the ground solid control system; as the softening point of asphalt continues to decrease, the density of the asphalt-contaminated slurry after screening is significantly reduced, the viscosity is greatly affected, and it is the most difficult to remove.

[0004] After drilling into asphalt contamination, for a small amount of asphalt invasion, increasing the density of the drilling fluid, pre-mixing diesel and emulsifiers can achieve certain treatment effects, but the effectiveness is not sustained; for a large amount of highly elastic or viscous asphalt pollution, increasing the density is not ideal, and chemical plugging, replacing part of the contaminated drilling fluid, or adding coolants, water-based wetting agents, curing agents and other treatment agents are often adopted. For example, the Yadavaran Oilfield in Iran has adopted treatment methods such as moderately increasing the density of the drilling fluid, replacing the slurry, mixing diesel to dilute and reduce viscosity, and adding asphalt oxidation curing agents for the asphalt heavy oil encountered in the drilling, but it still cannot completely and effectively solve the series of problems caused by the invasion of asphalt heavy oil, such as screen sticking, deterioration of drilling fluid performance, leakage in the same layer, and stuck drill. In the process of tar sand development in Canada, drilling in tar sand formations is prone to a series of complex problems such as sticking drill, sticking vibrating screen, blocking pipelines, and increasing non-production time. Since tar sands have relatively good fluidity and strong adhesion, drilling fluid coolants, water-based wetting agents and other additives are generally used on site, which have achieved certain results, but still cannot completely and effectively solve the complex technical problems of drilling in tar sand formations. Domestic research mainly solves the problem of asphalt pollution by adding asphalt inhibitors and performing "asphalt solidification" while drilling, passivating or solidifying the surface of heavy oil asphalt particles, and combining drilling fluid low solid phase, sealing, lubrication and other technologies. However, these asphalt inhibitors are mostly strong oxidizing treatment agents, such as H2O2, NaClO, benzoyl peroxide, etc. These materials are not only inconvenient to purchase and transport, but also flammable and explosive, and easily destroy the performance of drilling fluids. Abroad, polymer materials are mainly used to inhibit asphalt contamination in water-based drilling fluids. For example, Secure Energy (Drilling Services) uses polyamino acids (CA2945989) and hydrophobic polymers (US 2019 0169480A1) to inhibit asphalt contamination of cement drilling fluids; Uniquem INC. (Canada) points out that hydrophobically modified polysaccharides can also be used as asphalt inhibitors, and Innovative chemical technologies Canada LTD. (Canada) uses organic polysiloxanes / polyalkylene oxides to prevent asphalt from accumulating on drilling tools. However, there is very little research on polymer asphalt inhibitors in China, and related patents are rare. Therefore, it is urgent to develop inhibitors for water-based drilling fluids that resist formation asphalt contamination to fill the gap in asphalt inhibitor research. Summary of the invention

[0005] In order to solve at least one of the above problems, the present invention proposes a polyamine asphalt inhibitor for water-based drilling fluid, which has a strong ability to inhibit the adsorption and accumulation of asphalt on drilling tools.

[0006] The technical scheme of the present invention is as follows: a method for preparing an asphalt inhibitor for water-based drilling fluid, wherein an amino-terminated polyether is prepared by a catalytic amination method using polyether polyol, liquid ammonia and hydrogen as raw materials; the polyether polyol is at least one of polyethylene glycol, polypropylene glycol or ethylene glycol / propylene glycol copolymer.

[0007] As an embodiment of the present invention, the preparation method specifically comprises the following steps: S1, adding polyether polyol and Raney nickel catalyst into a reaction kettle, replacing with nitrogen and hydrogen, adding liquid ammonia and filling with hydrogen; wherein the molar ratio of liquid ammonia to polyether polyol is 5 to 12, and the molar ratio of hydrogen to polyether polyol is 0.5 to 1; S2, heat to 180-250°C under sealed and stirring conditions for reaction for 2-6 h; S3. Filter the reaction product, and remove the generated water and unreacted liquid ammonia from the filtered liquid by vacuum distillation to obtain an asphalt inhibitor.

[0008] Furthermore, the catalyst is at least one of a Ni catalyst, a Cu catalyst, a Cr catalyst or an Al catalyst.

[0009] Furthermore, the molecular weight of the polyether polyol is 200-2000.

[0010] Furthermore, the molecular weight of the polyether polyol is 200-400.

[0011] Furthermore, the molecular weight of the polyether polyol is 400.

[0012] One embodiment of the present invention is that the catalyst is added in an amount of 1 to 10% of the polyether polyol.

[0013] Another object of the present invention is to disclose an asphalt inhibitor for water-based drilling fluid, which is prepared by any of the above methods and has good ability to inhibit asphalt accumulation and adhesion.

[0014] The beneficial effects of the present invention are: The present invention utilizes a catalytic amination reaction, and the obtained product has good quality, high conversion rate, convenient subsequent treatment, and less environmental pollution. On the one hand, the primary amine group in the obtained polyamine inhibitor has a good adsorption effect on asphaltene, and the ether bond makes the polymer dissolve and has good dispersibility; on the other hand, the polyamine material has a good wrapping effect, which can flocculate asphalt substances, thereby inhibiting the adhesion and pollution of asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a graph showing the test results of the rigid rod adhesion experiment. DETAILED DESCRIPTION

[0016] In order to make the technical solutions and technical advantages of the present invention more clear, the technical solutions in the implementation process of the present invention will be clearly and completely described below in combination with embodiments and drawings.

[0017] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0018] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0019] Example 1 In a 1 L high-pressure reactor, 400 g of polypropylene glycol PPG-200 and 20 g of Raney nickel catalyst (Dalian General Chemical Co., Ltd., RTH-2110) were added, replaced with nitrogen and hydrogen respectively, and then liquid ammonia was added at one time, and hydrogen was filled in; wherein, the molar ratio of liquid ammonia to PPG-200 was 9, and the molar ratio of hydrogen to PPG-200 was 0.8. Then, stirring was turned on and heating was carried out, and the temperature was raised to 210°C, and the temperature was kept stable for 5 h. After the reaction was completed, the temperature was cooled to room temperature by circulating water, and the residual gas in the reactor was removed by vacuum, and the reactor was opened for discharge. The solid catalyst was filtered out through a Buchner funnel, and the liquid part was distilled under reduced pressure to remove the generated water and unreacted liquid ammonia to obtain asphalt inhibitor 1.

[0020] Example 2 In a 1 L high-pressure reactor, 400 g of polypropylene glycol PPG-400 and 20 g of Raney nickel catalyst (Dalian General Chemical Co., Ltd., RTH-2110) were added, replaced with nitrogen and hydrogen respectively, and then liquid ammonia was added at one time, and hydrogen was filled in; wherein, the molar ratio of liquid ammonia to PPG-400 was 9, and the molar ratio of hydrogen to PPG-400 was 0.8. Then, stirring was turned on and heating was carried out, and the temperature was raised to 210°C, and the temperature was kept stable for 5 h. After the reaction was completed, the temperature was cooled to room temperature through circulating water, and the residual gas in the reactor was removed by vacuum, and the reactor was opened for discharge. The solid catalyst was filtered out through a Buchner funnel, and the liquid part was distilled under reduced pressure to remove the generated water and unreacted liquid ammonia to obtain asphalt inhibitor 2.

[0021] Example 3 In a 1 L high-pressure reactor, 400 g of polypropylene glycol PPG-2000 and 20 g of Raney nickel catalyst (Dalian General Chemical Co., Ltd., RTH-2110) were added, and after being replaced with nitrogen and hydrogen respectively, liquid ammonia was added at one time, and hydrogen was filled in; wherein, the molar ratio of liquid ammonia to PPG-2000 was 9, and the molar ratio of hydrogen to PPG-2000 was 0.8. Then, stirring was turned on and heating was carried out, and the temperature was raised to 210°C, and the temperature was kept stable for 5 h. After the reaction was completed, the temperature was cooled to room temperature by circulating water, and the residual gas in the reactor was removed by vacuum, and the reactor was opened for discharge. The solid catalyst was filtered out through a Buchner funnel, and the liquid part was distilled under reduced pressure to remove the generated water and unreacted liquid ammonia to obtain asphalt inhibitor 3.

[0022] In order to further illustrate the effect of the inhibitor prepared in the above example, it is tested below.

[0023] Rigid rod adhesion experiment: a "4% bentonite slurry + 0.5% sodium carboxymethyl cellulose" system was prepared as a water-based drilling fluid. 4 g of asphalt inhibitor and 50 g of asphalt (softening point 49.4°C) were added to 400 mL of water-based drilling fluid, respectively. The steel rod was placed in an aging tank and hot-rolled at 90°C for 16 hours to simulate the invasion of formation asphalt. The adhesion of asphalt on the surface of the steel rod after hot rolling at 90°C / 16 hours was investigated (the inner wall of the aging tank was made of stainless steel with thermal insulation properties, and the material of the steel rod was high-strength alloy steel). The mass of asphalt adsorbed on the steel rod was weighed, the asphalt situation in the water-based drilling fluid was observed, and the inhibitory effect of the asphalt inhibitor was evaluated.

[0024] Table 1 Asphalt dispersion and adsorption in different formulations

[0025] Table 2 Adsorption of asphalt on steel rod in different formulations formula Adsorption capacity of rigid rod asphalt / g Base slurry 10.4 Base slurry + asphalt inhibitor 1 0.1 Base slurry + asphalt inhibitor 2 0 Base slurry + asphalt inhibitor 3 8.2

[0026] From Tables 1, 2 and Figure 1 It can be seen that in the blank sample, asphalt is mainly adsorbed on the steel rod and dispersed in the drilling fluid, and the adsorption amount on the steel rod is the highest, reaching 10.4g. After adding asphalt inhibitor 1 and asphalt inhibitor 2, the asphalt adsorption on the steel rod is almost 0; but in the drilling fluid containing asphalt inhibitor 1, a large amount of asphalt adheres to the tank wall of the aging tank. After adding asphalt inhibitor 3, more asphalt adheres to the steel rod, and the inhibition effect is not good. In summary, asphalt inhibitor 2 has the best effect.

[0027] The main difference between asphalt inhibitors 1, 2, and 3 is the molecular weight. It can be seen that asphalt inhibitor 2 with a moderate molecular weight has the best effect. The polyamine asphalt inhibitor can be dispersed or dissolved in water. It can be adsorbed on the surface of asphalt through amine groups, and wrap and flocculate asphaltene. On the one hand, it prevents asphalt from being adsorbed on steel rods, and on the other hand, it makes it easier to remove asphalt through solid control equipment such as vibrating screens, reducing the impact on drilling fluid performance.

[0028] The above descriptions are only some embodiments of the present invention and are not intended to limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an asphalt inhibitor for water-based drilling fluid, characterized in that: The amino-terminated polyether is prepared by catalytic amination with polyether polyol, liquid ammonia and hydrogen as raw materials; the polyether polyol is at least one of polyethylene glycol, polypropylene glycol or ethylene glycol / propylene glycol copolymer.

2. The method for preparing an asphalt inhibitor for water-based drilling fluid according to claim 1, characterized in that: The steps include: S1, adding polyether polyol and Raney nickel catalyst into a reaction kettle, replacing with nitrogen and hydrogen, adding liquid ammonia and filling with hydrogen; wherein the molar ratio of liquid ammonia to polyether polyol is 5 to 12, and the molar ratio of hydrogen to polyether polyol is 0.5 to 1; S2, heat to 180-250°C under sealed and stirring conditions for 2-6 h; S3. Filter the reaction product, and remove the generated water and unreacted liquid ammonia from the filtered liquid by vacuum distillation to obtain an asphalt inhibitor.

3. The method for preparing the asphalt inhibitor for water-based drilling fluid according to claim 1, characterized in that: The catalyst is at least one of a Ni-containing catalyst, a Cu catalyst, a Cr catalyst or an Al catalyst.

4. The method for preparing an asphalt inhibitor for water-based drilling fluid according to claim 1 or 2, characterized in that: The molecular weight of the polyether polyol is 200-2000.

5. The method for preparing asphalt inhibitor for water-based drilling fluid according to claim 4, characterized in that: The molecular weight of the polyether polyol is 200-400.

6. The method for preparing asphalt inhibitor for water-based drilling fluid according to claim 5, characterized in that: The molecular weight of the polyether polyol is 400.

7. The method for preparing an asphalt inhibitor for water-based drilling fluid according to claim 1 or 2, characterized in that: The catalyst is added in an amount of 1 to 10% of the polyether polyol.

8. An asphalt inhibitor for water-based drilling fluid, prepared by the method according to any one of claims 1 to 7.

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