Oil-based drilling fluid oil-clearing agent and preparation method thereof

Abstract

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 a sulfosuccinate salt and / or a polyoxyethylene ether compound; 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 utilizes components in specific amounts, and the components interact well with each other, resulting in an oil-based drilling fluid oil-clearing agent having an excellent cleaning effect and significantly improving the quality of the second interface bonding during cementing. Furthermore, 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.

Description

Technical Field

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

[0002] In recent years, with the continuous advancement of oil and gas exploration and development, the geological conditions encountered have become increasingly complex. Simultaneously, the exploration and development of shale oil and gas resources has placed increasingly stringent requirements on drilling fluids. Oil-based drilling fluids have been widely used as an effective method for resolving complex and challenging drilling problems and ensuring smooth drilling in shale oil and gas formations. However, oil-based drilling fluids and their filter cakes can adhere to the wellbore wall and are difficult to remove, resulting in poor cementation between the cement slurry and the wellbore, thus compromising cementing quality. Therefore, effectively removing oil-based drilling fluid adhesion from the wellbore wall is a crucial technical measure to ensure cementing quality.

[0003] Existing methods for removing oil-based drilling fluid from the wellbore wall primarily involve flushing with a flushing fluid containing an oil-clearing agent. A variety of oil-clearing agents are currently used both domestically and internationally, but all suffer from complex compositions, poor flushing efficiency, and inability to fully seal the interface. Therefore, developing an oil-clearing agent with high flushing efficiency and a wide range of applicability is of strategic importance 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-clearing 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] 2-15 parts by weight of penetrant;

[0007] 8-30 parts by weight of emulsifier;

[0008] 5-20 parts by weight of a complexing agent;

[0009] 0.5-2 parts by weight of dispersant;

[0010] 100 parts by weight of water;

[0011] The penetrant is selected from sulfosuccinate salts and / or polyoxyethylene ether compounds;

[0012] The emulsifier is a polyoxyethylene ether nonionic surfactant;

[0013] The complexing agent includes ethylenediaminetetraacetic acid sodium salt;

[0014] The dispersant is phosphate.

[0015] Preferably, the penetrant is selected from sodium salt of di-sec-octyl sulfosuccinate and / or polyoxyethylene ether.

[0016] Preferably, the emulsifier is selected from alkylphenol polyoxyethylene ether and / or polyoxyethylene sorbitan monooleate.

[0017] Preferably, the sodium salt of EDTA is selected from tetrasodium EDTA and / or disodium EDTA;

[0018] The complexing agent further comprises one or more of citric acid, sodium gluconate, sodium ethylenediaminetetramethylenephosphate and diethylenetriaminepenta(methylenephosphonate).

[0019] Preferably, the dispersant is selected from sodium pyrophosphate and / or sodium metaphosphate.

[0020] The present invention also provides a method for preparing the above-mentioned oil-based drilling fluid oil clearing agent, comprising the following steps:

[0021] S) The penetrant, emulsifier, complexing agent, dispersant and water are mixed and heated to react to obtain an oil-based drilling fluid clearing agent.

[0022] Preferably, the step S) is specifically as follows:

[0023] The penetrant is mixed with water and stirred for the first time, and 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.

[0024] 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; and the time of the first stirring, the second stirring, the third stirring, and the fourth stirring are each independently 5 to 20 min;

[0025] The temperature of the heating reaction is 30° C. to 50° C.; the time of the heating reaction is 0.5 to 2 h.

[0026] 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.

[0027] Preferably, the mass of the oil-based drilling fluid oil clearing agent is 5% to 20% of the mass of the cementing flushing fluid.

[0028] 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 a sulfosuccinate salt and / or a polyoxyethylene ether compound; 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 utilizes components in specific amounts, and the components interact well with each other, resulting in an oil-based drilling fluid oil-clearing agent having an excellent cleaning effect and significantly improving the quality of the second interface bonding during cementing. Furthermore, 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.

[0029] 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 0.94~2.2 g / cm 3 It is suitable for oil-based drilling fluids and formations with temperatures of 15~160°C, and has good environmental performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a diagram showing the flushing effect of the oil-based drilling fluid cleaning agent prepared in Example 4 of the present invention. DETAILED DESCRIPTION

[0031] 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 embodiments described 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 efforts are within the scope of protection of the present invention.

[0032] The present invention provides an oil-clearing agent for oil-based drilling fluid, 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 a sulfosuccinate salt and / or a polyoxyethylene ether compound; the emulsifier is a polyoxyethylene ether nonionic surfactant; the complexing agent includes sodium ethylenediaminetetraacetic acid; and the dispersant is a phosphate.

[0033] 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 even more preferably 5 to 10 parts by weight. In 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 with rapid penetration, facilitating the destruction of the oil film and filter cake on the well wall. In the present invention, the sulfosuccinate salt is preferably sodium di-sec-octyl succinate; and the polyoxyethylene ether compound is preferably polyoxyethylene ether.

[0034] 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, 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 oil-in-water 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.

[0035] The content of the complexing agent in the oil-based drilling fluid clearing 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 embodiments provided by the present invention, the content of the complexing agent in the oil-based drilling fluid clearing 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 ethylenediaminetetramethylenephosphate, 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 embodiments 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 separation of the emulsified oil film and filter cake from the well wall, and prevent them from re-adhering to the well wall, thereby improving the cleaning effect.

[0036] 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 uniformly dispersed in the flushing fluid 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.

[0037] The oil-based drilling fluid oil clearing agent provided by the present invention adopts components with specific contents, and the components have good interaction with each other, so that the obtained oil-based drilling fluid oil clearing agent has good cleaning effect. 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.

[0038] 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.

[0039] The present invention has no particular limitation 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.

[0040] 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 speed of the first stirring, the second stirring, the third stirring and the fourth stirring is each independently preferably 300~1000 r / min, more preferably 400~800 r / min, more preferably 500~700 r / min, and most preferably 600 r / min; the time of the first stirring, the second stirring, the third stirring and the fourth stirring is each independently preferably 5~20 min, more preferably 8~15 min, more preferably 8~12 min, and most preferably 10 min.

[0041] 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 2 h, more preferably 0.8 to 1.5 h, and even more preferably 1 to 1.2 h; the heating reaction is preferably carried out under stirring conditions; the stirring speed is preferably 300 to 1000 r / min, more preferably 400 to 800 r / min, even more preferably 500 to 700 r / min, and most preferably 500 to 600 r / min.

[0042] 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.

[0043] The mass of the oil-based drilling fluid oil clearing agent is preferably 5% to 20% of the mass of the cementing flushing fluid, and more preferably 7% to 15%.

[0044] 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%.

[0045] To further illustrate the present invention, an oil-clearing agent for oil-based drilling fluid and a preparation method thereof are described in detail below with reference to examples.

[0046] The reagents used in the following examples are all commercially available. The penetrant used in the examples was A1 sodium salt of di-sec-octyl sulfosuccinate or A2 polyoxyethylene ether compound (E-1310) provided by Nantong Yixun Chemical Technology Co., Ltd.; the emulsifier was B1 alkylphenol polyoxyethylene ether NP-10 or B2 polyoxyethylene sorbitan monooleate provided by Xingtai Xinlanxing Technology Co., Ltd.; the complexing agents were C1 tetrasodium ethylenediaminetetraacetic acid, C2 disodium ethylenediaminetetraacetic acid, C3 citric acid, and C4 sodium gluconate provided by Suzhou Changhong Chemical Co., Ltd.; C5 sodium ethylenediaminetetramethylenephosphate and C6 sodium diethylenetriaminepenta(methylenephosphonate) provided by Zaozhuang Ziyang Environmental Protection Technology Co., Ltd.; and the dispersants were D1 sodium pyrophosphate (Changzhou Chuanlin Chemical Co., Ltd.), D2 sodium hexametaphosphate (Suzhou Changhong Chemical Co., Ltd.), and D3 sodium metaphosphate (n is 1 provided by Hubei Wonder Chemical Co., Ltd.).

[0047] Example 1

[0048] (1) Add 10 g of Al to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0049] (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.

[0050] (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.

[0051] (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.

[0052] (5) The solution obtained in step (4) was heated to 30°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-1.

[0053] Example 2

[0054] (1) Add 7 g of Al to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0055] (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.

[0056] (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.

[0057] (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.

[0058] (5) The resulting solution was heated to 40°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain the oil-based drilling fluid cleaning agent MOD-2.

[0059] Example 3

[0060] (1) Add 5 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0061] (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.

[0062] (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.

[0063] (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.

[0064] (5) The solution obtained in step (4) was heated to 50°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-3.

[0065] Example 4

[0066] (1) Add 6 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0067] (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.

[0068] (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.

[0069] (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.

[0070] (5) The solution obtained in step (4) was heated to 45°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-4.

[0071] Example 5

[0072] (1) Add 10 g of Al to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0073] (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.

[0074] (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.

[0075] (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.

[0076] (5) The solution obtained in step (4) was heated to 30°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-5.

[0077] Example 6

[0078] (1) Add 9 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0079] (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.

[0080] (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.

[0081] (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.

[0082] (5) The solution obtained in step (4) was heated to 35°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-6.

[0083] Example 7

[0084] (1) Add 8 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0085] (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.

[0086] (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.

[0087] (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.

[0088] (5) The solution obtained in step (4) was heated to 40°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain oil-based drilling fluid clearing agent MOD-7.

[0089] The performance of the prepared oil-based drilling fluid oil cleaning agent was evaluated.

[0090] Evaluation method for flushing efficiency of oil-based drilling fluid cleaning agent:

[0091] (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.

[0092] (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 it out and weigh it, which is recorded as m2.

[0093] (3) Use oil-based drilling fluid cleaning agent to prepare flushing fluid.

[0094] (4) Install the outer cylinder with oil-based drilling fluid on the six-speed rotary viscometer, inject the flushing fluid into the six-speed rotary viscosity sample cup to the scale line, move the base frame so that the flushing fluid 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.

[0095] (5) Flushing efficiency calculation formula:

[0096] W=(m2-m3)×100 / (m2-m1) (1)

[0097] Where: w—is the flushing efficiency, %;

[0098] m1—total mass of the outer cylinder and sandpaper before soaking in oil-based drilling fluid, in g;

[0099] m2—mass of oil-based drilling fluid after immersion for 5 minutes, in g;

[0100] m3—The mass after flushing with flushing liquid for 8 minutes and drying for 2 hours, in g.

[0101] Flushing efficiency of MOD-1~MOD-7 prepared in Examples 1~7

[0102] Flushing fluid preparation method: Take 400 mL of clean water, add 8 g of suspending agent (Puyang Minghua Chemical Co., Ltd.), and then add 30-60 g of MOD-1-MOD-7 oil clearing agent respectively. Stir at 6000 r / min for 10 minutes. The experiment was carried out according to the flushing efficiency evaluation method mentioned above. The oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer has a density of 1.98 g / cm 3 The experimental results of Examples 1 to 7 are shown in Table 1.

[0103] The oil-based drilling fluid composition is 80% 0# diesel, 3% liquid emulsifier (Example 7 in Chinese Patent Publication No. CN109722230A), 3% powdered emulsifier (Example 6 in Chinese Patent Publication No. CN104592958A), 1% organic clay, 4% oxidized asphalt, 20% calcium chloride brine, and barite. Oil-based drilling fluids of varying densities can be obtained by adjusting the amount of barite added.

[0104] Table 1 Flushing efficiency of oil-based drilling fluid cleaning agents MOD-1 to MOD-7

[0105]

[0106] 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.

[0107] The flushing efficiency of different MOD-4 dosages prepared in Example 4 was evaluated by adding 8 g of suspending agent to 400 mL of water, followed by different amounts of MOD-4 oil clearing agent. The mixture was stirred at 6000 r / min for 10 minutes. The results of the experiment were shown in Table 2. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer was 1.0-2.2 g / cm 3 .

[0108] Table 2 Flushing efficiency of oil remover MOD-4 at different dosages

[0109]

[0110] 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 3 The oil-based drilling fluids all have good flushing effects, and the flushing efficiency is more than 90%. Among them, the embodiment of the present invention MOD-4 has a concentration of 15% and a density of 2.2 g / cm 3 The flushing effect diagram of oil-based drilling fluid is shown in Figure 1 .

[0111] The flushing efficiency of MOD-4 prepared in Example 4 was evaluated under different temperature conditions: 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 carried out 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 .

[0112] Table 3 Flushing efficiency under different temperature conditions

[0113]

[0114] From the results in Table 3, it can be seen that the flushing efficiency of the oil clearing agent prepared in Example 4 of the present invention increases with increasing temperature, and has a good flushing effect.

[0115] The heat 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 aged at 120°C, 150°C, and 180°C for 6 h, 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 rotation viscometer is 2.0 g / cm 3 .

[0116] Table 4 Flushing efficiency after aging

[0117]

[0118] As shown in Table 4, the oil cleaning agent prepared in Example 4 of the present invention has a flushing efficiency of over 90% after high-temperature aging, which can meet the needs of cementing after using oil-based drilling fluid in deep well drilling.

[0119] The salt tolerance of MOD-4 prepared in Example 4 was evaluated by taking 400 mL of clean water, adding 20 g, 40 g, 60 g, 100 g, 120 g, and 144 g of NaCl, 2 g, 4 g, and 8 g of CaCl2, respectively. After dissolution, 8 g of suspending agent was added, and 60 g of oil clearing agent MOD-4 was added. The mixture was stirred at a high speed of 6000 r / min for 10 minutes. 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 was 2.0 g / cm 3 .

[0120] Table 5 Salt tolerance evaluation results

[0121]

[0122] As shown in Table 5, the oil-clearing agent prepared in Example 4 of the present invention is used to prepare the flushing fluid using NaCl and CaCl2 brines of different concentrations, and the flushing efficiency exceeds 90%, which has a good flushing effect and can meet the requirements of the on-site mud shale formation for the inhibitory properties of the flushing fluid.

[0123] Comparative Example 1

[0124] (1) Add 6 g of A2 to 100 g of water and stir at a stirring rate of 600 r / min for 10 min.

[0125] (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.

[0126] (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.

[0127] (4) The solution obtained in step (3) was heated to 45°C, the reaction stirring rate was 500 r / min, and the reaction time was 1.0 h to obtain an oil-based drilling fluid clearing agent R.

[0128] Take 400 mL of clean water, add 8 g of suspending agent, and add 60 g of oil-based drilling fluid clearing agent R prepared in Comparative Example 1. Stir at 6000 r / min for 10 minutes. According to the flushing efficiency evaluation method, the flushing efficiency is 23.5%. The density of the oil-based drilling fluid used to soak the outer cylinder of the six-speed rotary viscometer is 2.2 g / cm 3 .

[0129] 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 principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An oil-clearing agent for oil-based drilling fluid, characterized in that: include: 2-15 parts by weight of penetrant; 8-30 parts by weight of emulsifier; 5-20 parts by weight of a complexing agent; 0.5-2 parts by weight of dispersant; 100 parts by weight of water; The complexing agent includes ethylenediaminetetraacetic acid sodium salt; The penetrant is selected from sodium salt of di-secondary octyl sulfosuccinate and / or polyoxyethylene ether; The emulsifier is selected from alkylphenol polyoxyethylene ether and / or polyoxyethylene sorbitan monooleate; The dispersant is selected from sodium pyrophosphate and / or sodium metaphosphate.

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

3. A method for preparing the oil-based drilling fluid clearing agent 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-based drilling fluid clearing agent.

4. The preparation method according to claim 3, characterized in that The step S) is specifically as follows: The penetrant is mixed with water and stirred for the first time, and 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.

5. The preparation method according to claim 4, characterized in that 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 are each 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 h.

6. 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.

7. The method of use according to claim 6, 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.

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