Oil cleaning agent for oil-based drilling fluid and preparation method of oil cleaning agent

Abstract

The invention provides an oil cleaning agent for an oil-based drilling fluid. The oil cleaning agent comprises the following components in parts by weight: 2-15 parts of a penetrant; 8-30 parts by weight of an emulsifier; 5-20 parts by weight of a complexing agent; 0.5-2 parts by weight of a dispersion promoting agent; 100 parts by weight of water; the penetrating agent is selected from a sulfosuccinate salt and / or a polyoxyethylene ether compound; the emulsifier is a polyoxyethylene ether nonionic surfactant; the complexing agent comprises ethylene diamine tetracetic acid sodium salt; the accelerating and dispersing agent is phosphate. Compared with the prior art, the oil cleaning agent for the oil-based drilling fluid, provided by the invention, adopts the components with specific contents, and the components have good interaction, so that the obtained oil cleaning agent for the oil-based drilling fluid has a good cleaning effect, can remarkably improve the two-interface cementation quality during well cementation, and has the advantages that the oil cleaning agent for the oil-based drilling fluid can be used for well cementation; the preparation method of the oil-based drilling fluid oil cleaning agent is simple, mild in condition and suitable for large-scale industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to an oil cleaning agent for oil-based drilling fluid and a preparation method thereof. Background Art

[0002] In recent years, with the continuous deepening of oil and gas exploration and development, the geological conditions encountered during drilling have become increasingly complex. At the same time, the exploration and development of shale oil and gas resources have placed higher and higher requirements on drilling fluids. Oil-based drilling fluids have been widely used as an effective method to solve difficult and complex problems and ensure the smooth drilling of shale oil and gas formations. However, oil-based drilling fluids and their filter cakes adhere to the well wall and are difficult to remove, resulting in poor cementation quality at the cement slurry interface, which affects the cementing quality. Therefore, effectively removing the adhesion of oil-based drilling fluids on the well wall is an important technical means to ensure cementing quality.

[0003] In the prior art, the method for eliminating the adhesion of oil-based drilling fluid on the well wall is mainly to use a flushing fluid containing an oil-cleaning agent to clean the well wall. There are many oil-cleaning agents currently used at home and abroad, but they all have the problems of complex composition, poor flushing efficiency, and inability to completely seal the two interfaces. Therefore, it is of great strategic significance to study an oil-cleaning agent with high flushing efficiency and wide application range to provide technical support for oil drilling. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide an oil-cleaning agent for oil-based drilling fluid with good flushing effect and a preparation method thereof.

[0005] The present invention provides an oil cleaning agent for oil-based drilling fluid, comprising:

[0006]

[0007] The penetrant is selected from sulfosuccinate salts and / or polyoxyethylene ether compounds;

[0008] The emulsifier is a polyoxyethylene ether nonionic surfactant;

[0009] The complexing agent includes ethylenediaminetetraacetic acid sodium salt;

[0010] The dispersant is phosphate.

[0011] Preferably, the penetrant is selected from di-sec-octyl sulfosuccinate sodium salt and / or polyoxyethylene ether.

[0012] Preferably, the emulsifier is selected from alkylphenol polyoxyethylene ether and / or polyoxyethylene sorbitan monooleate.

[0013] Preferably, the sodium salt of EDTA is selected from tetrasodium EDTA and / or disodium EDTA;

[0014] The complexing agent also includes one or more of citric acid, sodium gluconate, sodium ethylenediaminetetramethylenephosphate and diethylenetriaminepenta(methylenephosphonate).

[0015] Preferably, the dispersant is selected from sodium pyrophosphate and / or sodium metaphosphate.

[0016] The present invention also provides a method for preparing the above-mentioned oil-based drilling fluid cleaning agent, comprising the following steps:

[0017] S) The penetrant, emulsifier, complexing agent, dispersant and water are mixed and heated to react to obtain an oil-clearing agent for oil-based drilling fluid.

[0018] Preferably, the step S) is specifically:

[0019] The penetrant is mixed with water and stirred for the first time, then an emulsifier is added and stirred for the second time, a complexing agent is added and stirred for the third time, and a dispersant is added and stirred for the fourth time. After heating and reaction, an oil clearing agent for oil-based drilling fluid is obtained.

[0020] Preferably, the rotation speeds of the first stirring, the second stirring, the third stirring and the fourth stirring are each independently 300 to 1000 r / min; the time of the first stirring, the second stirring, the third stirring and the fourth stirring is each independently 5 to 20 min;

[0021] The temperature of the heating reaction is 30° C. to 50° C.; the time of the heating reaction is 0.5 to 2 hours.

[0022] The present invention also provides a method for using the oil-based drilling fluid oil-clearing agent, which comprises mixing the oil-based drilling fluid oil-clearing agent with a cementing flushing fluid.

[0023] Preferably, the mass of the oil-based drilling fluid cleaning agent is 5% to 20% of the mass of the cementing flushing fluid.

[0024] The present invention provides an oil-based drilling fluid oil-clearing agent, comprising: 2 to 15 parts by weight of a penetrant; 8 to 30 parts by weight of an emulsifier; 5 to 20 parts by weight of a complexing agent; 0.5 to 2 parts by weight of a dispersant; and 100 parts by weight of water; the penetrant is selected from sulfosuccinate salts and / or polyoxyethylene ether compounds; the emulsifier is a polyoxyethylene ether nonionic surfactant; the complexing agent includes sodium ethylenediaminetetraacetic acid; and the dispersant is a phosphate. Compared with the prior art, the oil-based drilling fluid oil-clearing agent provided by the present invention uses components with specific contents, and the components have good interactions with each other, so that the obtained oil-based drilling fluid oil-clearing agent has good cleaning effect, can significantly improve the two-interface cementation quality during cementing, and the preparation method of the oil-based drilling fluid oil-clearing agent is simple, the conditions are mild, and it is suitable for large-scale industrial production.

[0025] Experiments show that the oil-based drilling fluid cleaning agent provided by the present invention has a good flushing effect and is suitable for oil-based drilling fluids with a density of 0.94 to 2.2 g / cm 3 It is suitable for oil-based drilling fluid and formation temperature of 15 to 160°C, and has good environmental performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a diagram showing the flushing effect of the oil cleaning agent for oil-based drilling fluid prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The invention provides an oil cleaning agent for oil-based drilling fluid, comprising: 2-15 parts by weight of a penetrant; 8-30 parts by weight of an emulsifier; 5-20 parts by weight of a complexing agent; 0.5-2 parts by weight of a dispersant; and 100 parts by weight of water. The penetrant is a sulfosuccinate salt and / or a polyoxyethylene ether compound; the emulsifier is a polyoxyethylene ether nonionic surfactant; the complexing agent comprises sodium salt of ethylenediaminetetraacetic acid; and the dispersant is a phosphate.

[0029] The content of the penetrant in the oil-based drilling fluid clearing agent provided by the present invention is preferably 5 to 15 parts by weight, more preferably 5 to 12 parts by weight, and more preferably 5 to 10 parts by weight; in the embodiments provided by the present invention, the content of the penetrant in the oil-based drilling fluid clearing agent is specifically 10 parts by weight, 7 parts by weight, 5 parts by weight, 6 parts by weight, 9 parts by weight or 8 parts by weight; the penetrant is a sulfosuccinate salt and / or a polyoxyethylene ether compound, which is a nonionic or anionic surfactant, has a rapid penetration effect, and is conducive to destroying the oil film and filter cake of the well wall. In the present invention, the sulfosuccinate salt is preferably sodium salt of di-secondary octyl succinate; the polyoxyethylene ether compound is preferably polyoxyethylene ether.

[0030] The content of the emulsifier in the oil-based drilling fluid clearing agent provided by the present invention is preferably 8 to 25 parts by weight, and more preferably 10 to 20 parts by weight; in the embodiments provided by the present invention, the content of the emulsifier in the oil-based drilling fluid clearing agent is specifically 12 parts by weight, 14 parts by weight, 15 parts by weight, 20 parts by weight, 10 parts by weight or 16 parts by weight; the emulsifier is a polyoxyethylene ether nonionic surfactant, which has the effect of producing water-in-oil, and can emulsify the oil film and filter cake destroyed by the penetrant; in the present invention, the polyoxyethylene ether nonionic surfactant is preferably alkylphenol polyoxyethylene ether and / or polyoxyethylene sorbitan monooleate.

[0031] The content of the complexing agent in the oil-based drilling fluid cleaning agent provided by the present invention is preferably 8 to 20 parts by weight, more preferably 8 to 18 parts by weight, and even more preferably 8 to 15 parts by weight; in the embodiment provided by the present invention, the content of the complexing agent in the oil-based drilling fluid cleaning agent is specifically 15 parts by weight, 10 parts by weight, 12 parts by weight or 8 parts by weight; the complexing agent includes sodium salt of ethylenediaminetetraacetic acid; the sodium salt of ethylenediaminetetraacetic acid is preferably tetrasodium ethylenediaminetetraacetic acid and / or disodium ethylenediaminetetraacetic acid; the complexing agent preferably also includes one or more of citric acid, sodium gluconate, sodium ethylenediaminetetramethylene phosphate and diethylenetriaminepenta(methylenephosphonate); the mass of the sodium salt of ethylenediaminetetraacetic acid is preferably 20% to 100% of the mass of the complexing agent, more preferably 25% to 100%; in the embodiment provided by the present invention, the mass of the sodium salt of ethylenediaminetetraacetic acid is specifically 100%, 41%, 60%, 50% or 25% of the mass of the complexing agent. In the present invention, the complexing agent can combine with the metal ions in the oil-based drilling fluid, promote the emulsified oil film and filter cake to separate from the well wall, and no longer adhere to the well wall again, thereby improving the cleaning effect.

[0032] The content of the dispersant in the oil-based drilling fluid clearing agent provided by the present invention is preferably 1 to 2 parts by weight; in the embodiments provided by the present invention, the content of the dispersant in the oil-based drilling fluid clearing agent is specifically 1 part by weight, 1.5 parts by weight or 2 parts by weight; the dispersant is a phosphate, which can make the emulsified oil film and filter cake evenly dispersed in the flushing liquid, and has the effect of stabilizing the emulsion droplets; the phosphate is preferably sodium pyrophosphate and / or sodium metaphosphate; the sodium metaphosphate is (NaPO3) n ; In the present invention, n is preferably 1 or 6.

[0033] The oil-based drilling fluid oil cleaning agent provided by the present invention adopts components with specific contents, and the components have good interaction, so that the obtained oil-based drilling fluid oil cleaning agent has good cleaning effect, and the preparation method of the oil-based drilling fluid oil cleaning agent is simple, the conditions are mild, and it is suitable for large-scale industrial production.

[0034] The present invention also provides a method for preparing the above-mentioned oil-based drilling fluid oil clearing agent, comprising the following steps: S) mixing a penetrant, an emulsifier, a complexing agent, a dispersant and water, and heating the mixture to react to obtain the oil-based drilling fluid oil clearing agent.

[0035] The present invention has no special restrictions on the sources of all raw materials, and any raw materials available on the market can be used; the penetrant, emulsifier, complexing agent and dispersant are the same as those described above and will not be described in detail here.

[0036] The penetrant, emulsifier, complexing agent, dispersant and water are mixed; the mixing method is a method well known to those skilled in the art and is not particularly limited. In the present invention, it is preferably as follows: the penetrant and water are mixed for the first stirring, and then the emulsifier is added for the second stirring, the complexing agent is added for the third stirring, and the dispersant is added for the fourth stirring; the rotation speeds of the first stirring, the second stirring, the third stirring and the fourth stirring are each independently preferably 300-1000r / min, more preferably 400-800r / min, more preferably 500-700r / min, and most preferably 600r / min; the time of the first stirring, the second stirring, the third stirring and the fourth stirring is each independently preferably 5-20min, more preferably 8-15min, more preferably 8-12min, and most preferably 10min.

[0037] Then, a heating reaction is carried out to obtain an oil clearing agent for oil-based drilling fluid; the temperature of the heating reaction is preferably 30°C to 50°C; the time of the heating reaction is preferably 0.5 to 2h, more preferably 0.8 to 1.5h, and more preferably 1 to 1.2h; the heating reaction is preferably carried out under stirring; the stirring speed is preferably 300 to 1000r / min, more preferably 400 to 800r / min, more preferably 500 to 700r / min, and most preferably 500 to 600r / min.

[0038] The present invention also provides a method for using the oil-based drilling fluid oil-clearing agent, which comprises mixing the oil-based drilling fluid oil-clearing agent with a cementing flushing fluid.

[0039] The mass of the oil-based drilling fluid cleaning agent is preferably 5% to 20% of the mass of the cementing flushing fluid, and more preferably 7% to 15%.

[0040] The cementing flushing fluid can be any cementing flushing fluid well known to those skilled in the art without any special limitation. In the embodiment provided by the present invention, the cementing flushing fluid specifically includes water and a suspending agent; the mass of the suspending agent is preferably 0.5% to 5% of the mass of the cementing flushing fluid, more preferably 1% to 3%, and even more preferably 2%.

[0041] In order to further illustrate the present invention, an oil cleaning agent for oil-based drilling fluid and a preparation method thereof are described in detail below in conjunction with embodiments.

[0042] The reagents used in the following examples are all commercially available. The penetrant used in the examples is A1 sodium salt of dioctyl sulfosuccinate or A2 polyoxyethylene ether compound (E-1310) provided by Nantong Yixun Chemical Technology Co., Ltd.; the emulsifier is B1 alkylphenol polyoxyethylene ether NP-10 or B2 polyoxyethylene sorbitan monooleate provided by Xingtai Xinlanxing Technology Co., Ltd.; the complexing agent is C1 tetrasodium ethylenediaminetetraacetic acid, C2 disodium ethylenediaminetetraacetic acid, C3 citric acid, C4 sodium gluconate provided by Suzhou Changhong Chemical Co., Ltd., C5 sodium ethylenediaminetetramethylene phosphate, C6 sodium diethylenetriamine penta (methylene phosphonate) provided by Zaozhuang Ziyang Environmental Protection Technology Co., Ltd.; the dispersant is D1 sodium pyrophosphate (Changzhou Chuanlin Chemical Co., Ltd.), D2 sodium hexametaphosphate (provided by Suzhou Changhong Chemical Co., Ltd.), D3 sodium metaphosphate (n is 1 provided by Hubei Wande Chemical Co., Ltd.).

[0043] Example 1

[0044] (1) Add 10 g of Al to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0045] (2) Add 12 g of B1 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0046] (3) Add 15 g of C1 to the liquid obtained in step (2) and stir at a stirring rate of 600 r / min for 10 min.

[0047] (4) Add 1 g of D1 to the liquid obtained in step (3) and stir at a stirring rate of 600 r / min for 10 min.

[0048] (5) The solution obtained in step (4) was heated to 30° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil-based drilling fluid cleaning agent MOD-1 was obtained.

[0049] Example 2

[0050] (1) Add 7 g of A1 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0051] (2) Add 14 g of B2 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0052] (3) Add 5 g of C1 and 7 g of C5 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0053] (4) Add 1.5 g of D2 to the liquid obtained in step (3), and stir at a stirring rate of 600 r / min for 10 min.

[0054] (5) The obtained solution was heated to 40° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil-based drilling fluid cleaning agent MOD-2 was obtained.

[0055] Example 3

[0056] (1) Add 5 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0057] (2) Add 15 g of B2 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0058] (3) Add 9 g of C2 and 6 g of C3 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0059] (4) Add 1 g of D3 to the liquid obtained in step (3) and stir at a stirring rate of 600 r / min for 10 min.

[0060] (5) The solution obtained in step (4) was heated to 50° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil-based drilling fluid cleaning agent MOD-3 was obtained.

[0061] Example 4

[0062] (1) Add 6 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0063] (2) Add 20 g of B1 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0064] (3) Add 5 g of C1 and 5 g of C4 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0065] (4) Add 1.5 g of D1 to the liquid obtained in step (3), and stir at a stirring rate of 600 r / min for 10 min.

[0066] (5) The solution obtained in step (4) was heated to 45° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil-based drilling fluid cleaning agent MOD-4 was obtained.

[0067] Example 5

[0068] (1) Add 10 g of A1 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0069] (2) Add 10 g of B1 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0070] (3) Add 3 g of C1 and 9 g of C6 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0071] (4) Add 2 g of D2 to the liquid obtained in step (3) and stir at a stirring rate of 600 r / min for 10 min.

[0072] (5) The solution obtained in step (4) was heated to 30° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil cleaning agent MOD-5 for oil-based drilling fluid was obtained.

[0073] Example 6

[0074] (1) Add 9 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0075] (2) Add 20 g of B2 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0076] (3) Add 4 g of C2 and 4 g of C5 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0077] (4) Add 1 g of D1 to the liquid obtained in step (3) and stir at a stirring rate of 600 r / min for 10 min.

[0078] (5) The solution obtained in step (4) was heated to 35° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil cleaning agent MOD-6 for oil-based drilling fluid was obtained.

[0079] Example 7

[0080] (1) Add 8 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0081] (2) Add 16 g of B1 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0082] (3) Add 15 g of C1 to the liquid obtained in step (2) and stir at a stirring rate of 600 r / min for 10 min.

[0083] (4) Add 2 g of D3 to the liquid obtained in step (3), and stir at a stirring rate of 600 r / min for 10 min.

[0084] (5) The solution obtained in step (4) was heated to 40° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and the oil cleaning agent MOD-7 for oil-based drilling fluid was obtained.

[0085] The performance of the prepared oil-based drilling fluid cleaning agent was evaluated.

[0086] Evaluation method of flushing efficiency of oil cleaning agent for oil-based drilling fluid:

[0087] (1) Cut 80-grit sandpaper according to the circumference and height of the outer cylinder of the six-speed rotary viscometer, fix it on the surface of the outer cylinder, weigh it, and record its mass as m1.

[0088] (2) Immerse the outer cylinder of the six-speed rotary viscometer in step (1) into the oil-based drilling fluid so that the liquid level just covers the upper edge of the sandpaper. Soak for 5 minutes, take out and weigh it, and record it as m2.

[0089] (3) Use oil-based drilling fluid cleaning agent to prepare flushing fluid.

[0090] (4) Install the outer cylinder with oil-based drilling fluid on the six-speed rotating viscometer, inject the flushing liquid into the six-speed rotating viscosity sample cup to the scale line, move the base frame so that the flushing liquid level coincides with the scale line on the outer cylinder, rotate at a speed of 300 r / min for 8 min, remove the outer cylinder, place it in a 105℃ oven for 2 h, and weigh its mass again, recorded as m3.

[0091] (5) Flushing efficiency calculation formula:

[0092] W = (m2-m3) × 100 / (m2-m1) (1)

[0093] Where: w—is the flushing efficiency, %;

[0094] m1—Total mass of the outer cylinder and sandpaper before soaking in oil-based drilling fluid, in g;

[0095] m2—mass of oil-based drilling fluid after immersion for 5 minutes, in g;

[0096] m3—The mass after being rinsed with flushing liquid for 8 minutes and dried for 2 hours, in grams.

[0097] Flushing efficiency of MOD-1 to MOD-7 prepared in Examples 1 to 7

[0098] Preparation method of flushing fluid: Take 400mL of clean water, add 8g of suspending agent (Puyang Minghua Chemical Co., Ltd.), and then add 30-60g of MOD-1-MOD-7 oil clearing agent respectively, and stir for 10min under high-speed stirring conditions of 6000r / min. According to the above flushing efficiency evaluation method, the oil-based drilling fluid density used for soaking the outer cylinder of the six-speed rotating viscometer is 1.98g / cm 3 The experimental results of Examples 1 to 7 are shown in Table 1.

[0099] The oil-based drilling fluid is composed of 80% 0# diesel + 3% liquid emulsifier (Example 7 in the Chinese patent with publication number CN109722230A) + 3% powdered emulsifier (Example 6 in the Chinese patent with publication number CN104592958A) + 1% organic soil + 4% oxidized asphalt + calcium chloride brine (concentration of 20%) + barite. Different densities of oil-based drilling fluids are obtained by adjusting the amount of barite added.

[0100] Table 1 Flushing efficiency of oil-based drilling fluid cleaning agent MOD-1 to MOD-7

[0101] Example Oil cleaning agent Added amount, g Flushing efficiency, % 1 MOD-1 60 97.3 2 MOD-2 40 93.5 3 MOD-3 80 98.7 4 MOD-4 60 94.2 5 MOD-5 60 95.1 6 MOD-6 40 91.4 7 MOD-7 60 93.2

[0102] As shown in Table 1, the oil clearing agents prepared in Examples 1 to 7 of the present invention can meet the requirements of density up to 1.98 g / cm 3 The flushing efficiency is more than 90%, which has a good flushing effect.

[0103] The performance evaluation of the flushing efficiency of different amounts of MOD-4 prepared in Example 4 was carried out: 400 mL of clean water was added with 8 g of suspending agent, and different masses of MOD-4 oil clearing agents were added respectively, and stirred for 10 minutes under high-speed stirring conditions of 6000 r / min. The experiment was carried out according to the above flushing efficiency evaluation method, and the results were shown in Table 2. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotating viscometer was 1.0-2.2 g / cm 3 .

[0104] Table 2 Flushing efficiency of oil cleaning agent MOD-4 at different dosages and comparative examples

[0105]

[0106] From the results in Table 2, it can be seen that in Example 4 of the present invention, when the concentration is 10% to 20%, the density is 1.0 to 2.2 g / cm 3The oil-based drilling fluids have good flushing effects, and the flushing efficiency exceeds 90%. Among them, the MOD-4 in the embodiment of the present invention has a concentration of 15% and a density of 2.2g / cm 3 The flushing effect diagram of oil-based drilling fluid is shown in Figure 1 .

[0107] The flushing efficiency of MOD-4 prepared in Example 4 under different temperature conditions was evaluated: 400 mL of clean water was added with 8 g of suspending agent and 60 g of oil-clearing agent MOD-4, and stirred at 6000 r / min for 10 min. The obtained test solution was placed in a constant temperature water bath and the temperature was controlled to 15°C, 30°C, 60°C and 90°C respectively. The experiment was conducted according to the flushing efficiency evaluation method. The results are shown in Table 3. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer is 2.0 g / cm 3 .

[0108] Table 3 Flushing efficiency under different temperature conditions

[0109] Flushing temperature, °C Flushing efficiency, % 15 92.3 30 94.2 60 94.8 90 99.1

[0110] It can be seen from the results in Table 3 that the flushing efficiency of the oil cleaning agent prepared in Example 4 of the present invention increases with increasing temperature, and has a good flushing effect.

[0111] The temperature resistance of MOD-4 prepared in Example 4 was evaluated: 400 mL of clean water was added with 8 g of suspending agent and 60 g of oil clearing agent MOD-4, and stirred at 6000 r / min for 10 min. The obtained test solution was rolled and aged for 6 h at 120°C, 150°C and 180°C, and then taken out and cooled to room temperature. The experiment was conducted according to the flushing efficiency evaluation method. The results are shown in Table 4. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer is 2.0 g / cm 3 .

[0112] Table 4 Flushing efficiency after aging

[0113] Aging temperature, °C Flushing efficiency, % 120 93.5 150 94.5 180 96.2

[0114] From the results in Table 4, it can be seen that the oil cleaning agent prepared in Example 4 of the present invention has a flushing efficiency of more than 90% after high-temperature aging, which can meet the needs of cementing after using oil-based drilling fluid in deep well drilling.

[0115] The salt resistance of MOD-4 prepared in Example 4 was evaluated: 400 mL of clean water was taken, and 20 g, 40 g, 60 g, 100 g, 120 g, and 144 g of NaCl, 2 g, 4 g, and 8 g of CaCl2 were added respectively. After dissolving, 8 g of suspending agent was added, and 60 g of oil clearing agent MOD-4 was added respectively, and stirred for 10 min under high-speed stirring conditions of 6000 r / min. The experiment was conducted according to the flushing efficiency evaluation method. The results are shown in Table 5. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer is 2.0 g / cm 3 .

[0116] Table 5 Salt tolerance evaluation results

[0117] Salt dosage Flushing efficiency, % 20gNaCl 96.8 40gNaCl 95.7 60gNaCl 94.3 100gNaCl 92.7 144gNaCl 94.8 <![CDATA[2gCaCl2]]> 94.4 <![CDATA[4gCaCl2]]> 92.5 <![CDATA[8gCaCl2]]> 91.9

[0118] From the results in Table 5, it can be seen that the oil-clearing agent prepared in Example 4 of the present invention uses different concentrations of NaCl and CaCl2 brines to prepare the flushing liquid, and the flushing efficiency exceeds 90%, which has a good flushing effect and can meet the requirements of the on-site shale formation for the inhibitory property of the flushing liquid.

[0119] Comparative Example 1

[0120] (1) Add 6 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0121] (2) Add 20 g of B1 to the liquid obtained in step (1), and stir at a stirring rate of 600 r / min for 10 min.

[0122] (3) Add 1.5 g of D1 to the liquid obtained in step (2), and stir at a stirring rate of 600 r / min for 10 min.

[0123] (4) The solution obtained in step (3) was heated to 45° C., the reaction stirring rate was 500 r / min, the reaction time was 1.0 h, and an oil cleaning agent R for oil-based drilling fluid was obtained.

[0124] Take 400mL of clean water, add 8g of suspending agent, add 60g of oil-based drilling fluid clearing agent R prepared in Comparative Example 1, and stir for 10min at 6000r / min high-speed stirring. According to the flushing efficiency evaluation method, the flushing efficiency is 23.5%, and the density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotating viscometer is 2.2g / cm 3 .

[0125] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oil cleaning agent for oil-based drilling fluid, characterized in that: include: The penetrant is selected from sulfosuccinate salts and / or polyoxyethylene ether compounds; The emulsifier is a polyoxyethylene ether nonionic surfactant; The complexing agent includes ethylenediaminetetraacetic acid sodium salt; The dispersant is phosphate.

2. The oil cleaning agent for oil-based drilling fluid according to claim 1, characterized in that: The penetrant is selected from di-sec-octyl sulfosuccinate sodium salt and / or polyoxyethylene ether.

3. The oil cleaning agent for oil-based drilling fluid according to claim 1, characterized in that: The emulsifier is selected from alkylphenol polyoxyethylene ether and / or polyoxyethylene sorbitan monooleate.

4. The oil cleaning agent for oil-based drilling fluid according to claim 1, characterized in that: The sodium salt of EDTA is selected from tetrasodium EDTA and / or disodium EDTA; The complexing agent also includes one or more of citric acid, sodium gluconate, sodium ethylenediaminetetramethylenephosphate and diethylenetriaminepenta(methylenephosphonate).

5. The oil cleaning agent for oil-based drilling fluid according to claim 1, characterized in that: The dispersant is selected from sodium pyrophosphate and / or sodium metaphosphate.

6. A method for preparing the oil-clearing agent for oil-based drilling fluid according to claim 1, characterized in that: The following steps are involved: S) The penetrant, emulsifier, complexing agent, dispersant and water are mixed and heated to react to obtain an oil-clearing agent for oil-based drilling fluid.

7. The preparation method according to claim 6, characterized in that: The step S) is specifically: The penetrant is mixed with water and stirred for the first time, then an emulsifier is added and stirred for the second time, a complexing agent is added and stirred for the third time, and a dispersant is added and stirred for the fourth time. After heating and reaction, an oil clearing agent for oil-based drilling fluid is obtained.

8. The preparation method according to claim 7, characterized in that: The rotation speeds of the first stirring, the second stirring, the third stirring and the fourth stirring are independently 300 to 1000 r / min; the time of the first stirring, the second stirring, the third stirring and the fourth stirring is independently 5 to 20 min; The temperature of the heating reaction is 30° C. to 50° C.; the time of the heating reaction is 0.5 to 2 hours.

9. A method for using the oil-based drilling fluid cleaning agent according to claim 1, characterized in that: Mix the oil-based drilling fluid with the oil-clearing agent and the cementing flushing fluid.

10. The method of use according to claim 9, characterized in that: The mass of the oil-based drilling fluid oil-clearing agent is 5% to 20% of the mass of the cementing flushing fluid.

Images