CN115247052B - Oil-based drilling fluid plugging agent and preparation method thereof - Google Patents
Oil-based drilling fluid plugging agent and preparation method thereof Download PDFInfo
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- CN115247052B CN115247052B CN202110457692.2A CN202110457692A CN115247052B CN 115247052 B CN115247052 B CN 115247052B CN 202110457692 A CN202110457692 A CN 202110457692A CN 115247052 B CN115247052 B CN 115247052B
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- 239000012530 fluid Substances 0.000 title claims abstract description 96
- 238000002360 preparation method Methods 0.000 title claims abstract description 30
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- JIGUQPWFLRLWPJ-UHFFFAOYSA-N Ethyl acrylate Chemical compound CCOC(=O)C=C JIGUQPWFLRLWPJ-UHFFFAOYSA-N 0.000 claims description 8
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- IMFACGCPASFAPR-UHFFFAOYSA-N tributylamine Chemical group CCCCN(CCCC)CCCC IMFACGCPASFAPR-UHFFFAOYSA-N 0.000 claims description 8
- CIHOLLKRGTVIJN-UHFFFAOYSA-N tert‐butyl hydroperoxide Chemical compound CC(C)(C)OO CIHOLLKRGTVIJN-UHFFFAOYSA-N 0.000 claims description 7
- USHAGKDGDHPEEY-UHFFFAOYSA-L potassium persulfate Chemical compound [K+].[K+].[O-]S(=O)(=O)OOS([O-])(=O)=O USHAGKDGDHPEEY-UHFFFAOYSA-L 0.000 claims description 5
- KOMNUTZXSVSERR-UHFFFAOYSA-N 1,3,5-tris(prop-2-enyl)-1,3,5-triazinane-2,4,6-trione Chemical compound C=CCN1C(=O)N(CC=C)C(=O)N(CC=C)C1=O KOMNUTZXSVSERR-UHFFFAOYSA-N 0.000 claims description 4
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- ZODWTWYKYYGSFS-UHFFFAOYSA-N diphenyl-bis(prop-2-enyl)silane Chemical compound C=1C=CC=CC=1[Si](CC=C)(CC=C)C1=CC=CC=C1 ZODWTWYKYYGSFS-UHFFFAOYSA-N 0.000 claims description 3
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- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 2
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Abstract
The invention discloses an oil-based drilling fluid plugging agent and a preparation method thereof, and belongs to the field of petrochemical industry. The preparation method of the oil-based drilling fluid plugging agent comprises the following steps: reacting divinyl dimethyl silane with diphenyl chloromethane in the presence of a catalyst and an initiator to obtain a crosslinking agent; uniformly mixing a cross-linking agent, an emulsifying agent, a high-temperature resistant monomer, an ester monomer and a polyene monomer to form a pre-emulsion; in the presence of an initiator, carrying out polymerization reaction on the pre-emulsion to obtain an oil-based drilling fluid plugging agent; the high temperature resistant monomer is at least one selected from styrene, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone. The preparation method can prepare the plugging agent with excellent high temperature resistance and plugging property, and can be suitable for ultra-deep oil and gas drilling and heterogeneous reservoirs with more cracks and pores when the plugging agent is used in oil-based drilling fluid.
Description
Technical Field
The invention relates to the field of petrochemical industry, in particular to an oil-based drilling fluid plugging agent and a preparation method thereof.
Background
Oil-based drilling fluid has strong temperature resistance and can effectively inhibit rock hydration, and is widely used for drilling complex formations such as shale gas. However, the phenomenon of well wall instability still exists in the oil-based drilling fluid drilling process, mainly because the oil-based drilling fluid enters a rock microcrack, and pressure transmission is generated under the action of hydrostatic column pressure, so that the well wall instability is caused. In addition, the oil-based drilling fluid easily flows into the lipophilic channel of the well wall, and is difficult to block after leakage due to small flowing resistance. The plugging agent is important for improving the plugging capability of the oil-based drilling fluid, so that it is necessary to provide a plugging agent suitable for the oil-based drilling fluid.
The related art provides an oil-based drilling fluid pressure-bearing plugging agent which is formed by chemical reaction and physical mixing, and consists of a copolymer obtained by copolymerizing three monomers of alkenylbenzene, acrylic ester and acrylic acid and an oleophilic hard inorganic material, wherein the mass ratio of alkenylbenzene, acrylic ester, acrylic acid and the oleophilic hard inorganic material is 15-30:10-25:1:8-20.
In the process of implementing the present invention, the inventors found that there are at least the following problems in the related art:
the temperature resistance of the plugging agent provided by the related art needs to be improved.
Disclosure of Invention
In view of the above, the present invention provides an oil-based drilling fluid plugging agent and a preparation method thereof, which can solve the above technical problems.
Specifically, the method comprises the following technical scheme:
in one aspect, a method for preparing an oil-based drilling fluid plugging agent is provided, the method for preparing the oil-based drilling fluid plugging agent comprises:
Reacting divinyl dimethyl silane with diphenyl chloromethane in the presence of a catalyst and an initiator to obtain a crosslinking agent;
Uniformly mixing the cross-linking agent, the emulsifying agent, the high temperature resistant monomer, the ester monomer and the polyene monomer to form a pre-emulsion;
In the presence of an initiator, carrying out polymerization reaction on the pre-emulsion to obtain the oil-based drilling fluid plugging agent;
wherein the high temperature resistant monomer is at least one selected from styrene, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone.
In some possible implementations, the reacting divinyl dimethylsilane and diphenyl chloromethane in the presence of a catalyst and an initiator to obtain the crosslinking agent comprises:
Placing the divinyl dimethyl silane and the diphenyl chloromethane into a first reactor, and dropwise adding the catalyst into the first reactor at the rotating speed of 180-250 r/min and the temperature of 50-75 ℃;
After the catalyst is added dropwise, heating a reaction system to 80-95 ℃, and then adding an initiator into the first reactor;
and (3) increasing the rotating speed to 300r/min-350r/min, and performing reaction for a set time to obtain the cross-linking agent.
In some possible implementations, the catalyst is tri-n-butylamine.
In some possible implementations, the initiator is selected from at least one of ammonium persulfate, potassium persulfate, sodium bisulfite, sodium sulfite, t-butyl hydroperoxide.
In some possible implementations, the uniformly mixing the crosslinking agent, the emulsifier, the high temperature resistant monomer, the ester monomer, and the polyene monomer to form a pre-emulsion includes:
Pre-adding the emulsifier into a second reactor filled with deionized water;
Then continuously adding the cross-linking agent into the second reactor, and uniformly stirring;
Continuously adding the high-temperature resistant monomer, the ester monomer and the polyene monomer into the second reactor, and uniformly stirring to obtain the pre-emulsion.
In some possible implementations, the emulsifier is selected from at least one of emulsifier OP-10, emulsifier OS, span 80.
In some possible implementations, the ester monomer is selected from at least one of methyl methacrylate, butyl acrylate, ethyl acrylate, 2-methyl methacrylate.
In some possible implementations, the polyene monomer is selected from at least one of triallyl isocyanurate, divinylbenzene, diallyldiphenylsilane.
In some possible implementations, the polymerizing the pre-emulsion in the presence of an initiator to obtain the oil-based drilling fluid plugging agent includes:
transferring the pre-emulsion into a third reactor, adding an initiator into the third reactor under the conditions of introducing nitrogen and stirring, and then reacting for a set time under the condition of 65-85 ℃ to obtain the oil-based drilling fluid plugging agent.
On the other hand, an oil-based drilling fluid plugging agent is provided, and the oil-based drilling fluid plugging agent is prepared by adopting the preparation method.
The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:
according to the preparation method of the oil-based drilling fluid plugging agent, provided by the embodiment of the invention, the divinyl dimethyl silane and the diphenyl chloromethane are reacted, and the obtained crosslinking agent has good temperature resistance, is not easy to degrade at high temperature, and has higher stability. In the process of synthesizing the plugging agent, not only the cross-linking agent but also a high-temperature resistant monomer is used, wherein the high-temperature resistant monomer is at least one selected from styrene, 2-acrylamide-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone, and has better thermal stability, so that the high-temperature resistance of the plugging agent can be further improved. Under the condition that an emulsifier exists, the particle size of the synthesized plugging agent is in a nanoscale, so that nanoscale microcracks and/or pores in shale can be effectively plugged, and a good plugging effect is achieved. Therefore, the plugging agent with excellent high temperature resistance and plugging property can be prepared by the preparation method, and can be suitable for ultra-deep oil and gas drilling and heterogeneous reservoirs with more cracks and pores when being used in oil-based drilling fluid.
Detailed Description
In order to make the technical scheme and advantages of the present invention more apparent, the following detailed description of the embodiments of the present invention will be provided.
In one aspect, the embodiment of the invention provides a preparation method of an oil-based drilling fluid plugging agent, which comprises the following steps:
and step 1, reacting divinyl dimethyl silane and diphenyl chloromethane in the presence of a catalyst and an initiator to obtain the cross-linking agent.
And step2, uniformly mixing the cross-linking agent, the emulsifying agent, the high-temperature resistant monomer, the ester monomer and the polyene monomer to form the pre-emulsion.
And step 3, carrying out polymerization reaction on the pre-emulsion in the presence of an initiator to obtain the oil-based drilling fluid plugging agent.
Wherein the high temperature resistant monomer is at least one selected from styrene, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone, that is, the high temperature resistant monomer can be any selected from one or a combination of any two or any three or a combination of four of styrene, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone. When two or more high temperature resistant monomers are selected in combination, the mass ratio between the monomers may be any ratio, and the embodiment of the present invention is not particularly limited herein.
Compared with the polymer composed of alkyl carbon chains, the high-temperature resistant monomer has better thermal stability, the decomposition temperature is even up to 350 ℃, in addition, the styrene has extremely high rigidity, for example, the thermal movement of molecular chains can be greatly hindered under the high-temperature condition, and the high-temperature resistant monomer is beneficial to improving the temperature resistance of the plugging agent and the pressure-bearing performance of the plugging agent.
According to the preparation method of the oil-based drilling fluid plugging agent, provided by the embodiment of the invention, the divinyl dimethyl silane and the diphenyl chloromethane are reacted, and the obtained crosslinking agent has good temperature resistance, is not easy to degrade at high temperature, and has higher stability. In the process of synthesizing the plugging agent, not only the cross-linking agent but also a high-temperature resistant monomer is used, wherein the high-temperature resistant monomer is at least one selected from styrene, 2-acrylamide-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone, and has better thermal stability, so that the high-temperature resistance of the plugging agent can be further improved. Under the condition that an emulsifier exists, the particle size of the synthesized plugging agent is in a nanoscale, so that nanoscale microcracks and/or pores in shale can be effectively plugged, and a good plugging effect is achieved. Therefore, the plugging agent with excellent high temperature resistance and plugging property can be prepared by the preparation method, and can be suitable for ultra-deep oil and gas drilling and heterogeneous reservoirs with more cracks and pores when being used in oil-based drilling fluid.
The steps involved in the above preparation method will be described below:
For step 1, the divinyl dimethylsilane and the diphenylmethane chloride are reacted in the presence of a catalyst and an initiator to obtain a cross-linking agent, which further comprises the steps of:
step 101, placing divinyl dimethyl silane and diphenyl chloromethane into a first reactor, and dropwise adding a catalyst into the first reactor at the rotating speed of 180-250 r/min and the temperature of 50-75 ℃.
Illustratively, the first reactor may be a three-necked flask to facilitate the agitation and warming operations described above.
Illustratively, the mass ratio of divinyl dimethylsilane to diphenylmethane may be 3-20:1, such as 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, etc., further, the mass ratio of divinyl dimethylsilane to diphenylmethane may be 6-10:1.
The catalyst may be slowly dropped into the first reactor to obtain a good dispersion effect, and for example, the catalyst used may be tri-n-butylamine, which can obtain an excellent catalytic effect.
Step 102, after the catalyst is added dropwise, heating the reaction system to 80-95 ℃, and then adding an initiator into the first reactor.
Illustratively, suitable initiators include, but are not limited to: at least one of ammonium persulfate, potassium persulfate, sodium bisulphite, sodium sulfite and tert-butyl hydroperoxide.
Step 103, the rotating speed is increased to 300r/min-350r/min, and the reaction setting time is carried out, so that the cross-linking agent is obtained.
Step 103 is capable of fully conducting the reaction and facilitating heat dissipation in the reaction process by increasing the rotating speed to 300r/min-350 r/min. The reaction time may be from 4 to 8 hours, for example from 5 to 6 hours. After the reaction is finished and the reaction system is cooled, the obtained reaction product is the cross-linking agent expected in the embodiment of the invention.
For example, step 1 may be performed by:
Sequentially adding 50-100g of divinyl dimethyl silane and 5-15g of diphenyl chloromethane into a 250ml three-neck flask, slowly dripping 0.05-0.10 g of tri-n-butylamine catalyst into the flask at 180-250 r/min and 50-75 ℃, continuously heating to 80-95 ℃, adding an initiator ammonium persulfate into the three-neck flask, then increasing the rotating speed to 300-350 r/min, and reacting for 4-8 hours to obtain the high-temperature-resistant cross-linking agent.
For step 2, uniformly mixing the cross-linking agent, the emulsifying agent, the high temperature resistant monomer, the ester monomer and the polyene monomer to form a pre-emulsion, wherein the method comprises the following steps of:
Step 201, adding the emulsifier into a second reactor filled with deionized water in advance. The second reactor may be, for example, a beaker.
Step 202, continuously adding the cross-linking agent into the second reactor, and uniformly stirring. For example, the stirring speed may be 450r/min to 550r/min, for example 500r/min, etc., and the stirring time may be 25min to 35min, for example 30min.
And 203, continuously adding the high-temperature resistant monomer, the ester monomer and the polyene monomer into the second reactor, and uniformly stirring to obtain the pre-emulsion. For example, the stirring speed may be 900r/min to 1100r/min, for example 1000r/min, and the stirring time may be 25min to 35min, for example 30min.
Illustratively, the mass ratio of the emulsifier, the cross-linking agent, the high temperature resistant monomer, the ester monomer and the polyene monomer is 3-8:15-50:20-50:0.5-1.0. For example, the mass number of emulsifiers includes, but is not limited to: 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, etc.; the mass number of the crosslinking agent includes, but is not limited to: 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.; the mass number of the high temperature resistant monomer includes, but is not limited to: 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc.; the mass number of the polyene monomer includes, but is not limited to: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, etc.
Illustratively, the emulsifier is selected from at least one of emulsifier OP-10, emulsifier OS, span 80.
Illustratively, the ester monomer is selected from at least one of methyl methacrylate, butyl acrylate, ethyl acrylate, and 2-methyl methacrylate.
Illustratively, the polyene monomer is selected from at least one of triallyl isocyanurate, divinylbenzene, diallyldiphenylsilane.
Wherein, when the emulsifier, the ester monomer and the polyene monomer are selected from two or more combinations, the mass ratio between the components may be any ratio, and the embodiments of the present invention are not particularly limited herein.
For example, step 2 may be performed by:
Slowly dripping 2-8g of emulsifier OP-10 into a beaker filled with 200g of deionized water, then adding 3-8g of high temperature-resistant cross-linking agent into the beaker, stirring for 30min at the stirring speed of 450-550 r/min, then sequentially adding 15-50g of high temperature-resistant monomer, 20-50g of ester monomer and 0.5-1.0g of polyene monomer, and stirring for 25-35 min at the stirring speed of 900-1100 r/min to form stable pre-emulsion.
For step 3, polymerizing the pre-emulsion in the presence of an initiator to obtain an oil-based drilling fluid plugging agent, which further comprises:
Transferring the pre-emulsion into a third reactor, adding an initiator into the third reactor under the conditions of introducing nitrogen and stirring, and then reacting for a set time at 65-85 ℃ to obtain the oil-based drilling fluid plugging agent.
Wherein, the initiator can be selected in a solution form, and the mass fraction of the initiator in the solution can be 15% -25%, for example 20%, etc., so as to obtain good initiation effect.
Illustratively, suitable initiators include, but are not limited to: at least one of ammonium persulfate, potassium persulfate, sodium bisulphite, sodium sulfite and tert-butyl hydroperoxide.
When the initiator is of the type described above, the solution of the initiator may be an aqueous solution of the initiator.
For example, step 3 may be performed by:
The pre-emulsion prepared as described above is transferred to a third reactor, nitrogen is introduced into the third reactor, and the stirring speed is maintained at 150r/min to 250r/min, for example 200r/min. Then, under the stirring condition, adding 2ml-5ml of an initiator aqueous solution with the mass concentration of 20% into a third reactor, and reacting for 4h-6h at the temperature of 65-85 ℃ to obtain a reaction product, namely the oil-based drilling fluid plugging agent expected by the application.
On the other hand, the embodiment of the invention also provides an oil-based drilling fluid plugging agent, which is prepared by adopting the preparation method.
The plugging agent for the oil-based drilling fluid provided by the embodiment of the invention has excellent high temperature resistance, has the particle size of nano scale, can effectively plug nano-scale microcracks and/or pores in shale, has a good plugging effect, and can be suitable for ultra-deep oil gas drilling and is suitable for heterogeneous reservoirs with more cracks and pores when being used in the oil-based drilling fluid.
The invention will be further described by means of specific examples:
Example 1
This example 1 prepared an oil-based drilling fluid plugging agent, the preparation method of which is as follows:
Preparation of high temperature resistant cross-linking agent:
70g of divinyl dimethyl silane and 10g of diphenyl chloromethane are put into a three-neck flask which is sequentially added with 250ml of the three-neck flask, 0.075g of tri-n-butylamine is slowly dripped into the flask at 200r/min and 60 ℃, the temperature is continuously increased to 90 ℃, ammonium persulfate serving as an initiator is added into the three-neck flask, the rotating speed is increased to 300r/min, the reaction is carried out for 5h, and after the reaction is completed, a reaction product is taken out and cooled, so that the high-temperature-resistant cross-linking agent is obtained.
Preparation of the pre-emulsion:
Firstly, 3g of an emulsifier OP-10 is slowly dripped into a beaker filled with 200g of deionized water, then 4g of a cross-linking agent is added into the beaker, and the mixture is stirred for 30min at a stirring speed of 500r/min, then 30g of styrene, 20g of methyl methacrylate, 10g of ethyl acrylate and 0.6g of divinylbenzene are sequentially added into the beaker, and the mixture is stirred for 30min at a stirring speed of 1000r/min, so that a stable pre-emulsion is formed.
And (3) synthesis of a plugging agent:
Transferring the prepared pre-emulsion into a reaction container, introducing nitrogen into the reaction container, keeping the stirring speed at 200r/min, adding 3ml of 20% (mass fraction) ammonium persulfate aqueous solution into the reaction container, and reacting for 4 hours at 70 ℃, wherein the obtained emulsion is the oil-based drilling fluid plugging agent provided in the embodiment 1.
Example 2
This example 2 prepared an oil-based drilling fluid plugging agent, the preparation method of which is as follows:
Preparation of high temperature resistant cross-linking agent:
80g of divinyl dimethyl silane and 10g of diphenylmethane are put into a three-neck flask which is sequentially added with 250ml of the three-neck flask, 0.08g of catalyst tri-n-butylamine is slowly dripped into the flask at 220r/min and 70 ℃, the temperature is continuously heated to 85 ℃, initiator ammonium persulfate is added, the rotating speed is increased to 350r/min, the reaction is carried out for 6 hours, and the high-temperature-resistant cross-linking agent is obtained after taking out and cooling after the reaction is completed.
Preparation of the pre-emulsion:
Firstly, 5g of emulsifier OP-10 is slowly dripped into a beaker filled with 200g of deionized water, then 8g of high temperature-resistant cross-linking agent is added into the beaker, the mixture is stirred for 40min at a stirring speed of 450r/min, then 30g of styrene, 25g of methyl methacrylate, 10g of butyl acrylate and 0.6g of triallyl isocyanurate are sequentially added, and the mixture is stirred for 30min at a stirring speed of 1100r/min, so that stable pre-emulsion is formed.
And (3) synthesis of a plugging agent:
Transferring the prepared pre-emulsion into a reaction container, introducing nitrogen into the reaction container, keeping the stirring speed at 200r/min, adding 4ml of 20% (mass fraction) potassium persulfate aqueous solution into the reaction container, and reacting at 75 ℃ for 5 hours to obtain emulsion, namely the oil-based drilling fluid plugging agent provided in the embodiment 2.
Example 3
This example 3 prepared an oil-based drilling fluid plugging agent, the preparation method of which is as follows:
Preparation of high temperature resistant cross-linking agent:
60g of divinyl dimethyl silane and 8g of diphenyl chloromethane are put into a three-neck flask which is sequentially added with 250ml of the three-neck flask, 0.06g of tri-n-butylamine is slowly dripped into the flask at 180r/min and 50 ℃, the temperature is continuously heated to 80 ℃, ammonium persulfate serving as an initiator is added into the three-neck flask, the rotating speed is increased to 300r/min, the reaction is carried out for 5h, and after the reaction is completed, a reaction product is taken out and cooled, so that the high-temperature-resistant cross-linking agent is obtained.
Preparation of the pre-emulsion:
firstly, 3g of emulsifier span 80 is slowly dripped into a beaker filled with 200g of deionized water, then 4g of cross-linking agent is added into the beaker, and the mixture is stirred for 30min at a stirring speed of 500r/min, then 40g of sodium styrene sulfonate, 15g of methyl methacrylate, 15g of ethyl acrylate and 0.7g of divinylbenzene are sequentially added into the beaker, and the mixture is stirred for 35min at a stirring speed of 1000r/min, so that stable pre-emulsion is formed.
And (3) synthesis of a plugging agent:
Transferring the prepared pre-emulsion into a reaction container, introducing nitrogen into the reaction container, keeping the stirring speed at 200r/min, adding 3ml of 20% (mass fraction) ammonium persulfate aqueous solution into the reaction container, and reacting for 4 hours at 70 ℃, wherein the obtained emulsion is the oil-based drilling fluid plugging agent provided in the embodiment 3.
Example 4
This example 4 prepared an oil-based drilling fluid plugging agent, the preparation method of which is as follows:
Preparation of high temperature resistant cross-linking agent:
90g of divinyl dimethyl silane and 10g of diphenyl chloromethane are put into a three-neck flask which is sequentially added with 250ml of the three-neck flask, 0.085g of catalyst tri-n-butylamine is slowly dripped into the flask at 200r/min and 60 ℃, the temperature is continuously increased to 90 ℃, an initiator ammonium persulfate is added into the three-neck flask, the rotating speed is increased to 300r/min, the reaction is carried out for 5h, and after the reaction is completed, a reaction product is taken out and cooled, so that the high-temperature-resistant cross-linking agent is obtained.
Preparation of the pre-emulsion:
Firstly, 3g of an emulsifier OP-10 is slowly dropped into a beaker filled with 200g of deionized water, then 6g of a cross-linking agent is added into the beaker, and the mixture is stirred for 30min at a stirring speed of 500r/min, then 30g of 2-acrylamido-2-methylpropanesulfonic acid, 25g of 2-methyl methacrylate, 15g of ethyl acrylate and 0.6g of divinylbenzene are sequentially added into the beaker, and the mixture is stirred for 30min at a stirring speed of 1000r/min, so that a stable pre-emulsion is formed.
And (3) synthesis of a plugging agent:
Transferring the prepared pre-emulsion into a reaction container, introducing nitrogen into the reaction container, keeping the stirring speed at 200r/min, adding 3ml of 20% (mass fraction) sodium sulfite aqueous solution into the reaction container, and reacting for 6 hours at 85 ℃, wherein the obtained emulsion is the oil-based drilling fluid plugging agent provided in the embodiment 4.
Example 5
The technical scheme adopted is the same as that of the embodiment 1, and the difference is that: the divinylbenzene loading was 0.9g.
Example 6
The technical scheme adopted is the same as that of the embodiment 1, and the difference is that: the amount of the emulsifier OP-10 added is 7g.
Comparative example 1
The technical scheme adopted is basically the same as that of the embodiment 1, and the difference is that: the preparation and addition of the crosslinking agent are not involved.
Comparative example 2
The technical scheme adopted is basically the same as that of the embodiment 2, and the difference is that: the amount of styrene was adjusted to 10g.
Comparative example 3
The technical scheme adopted is basically the same as that of the embodiment 1, and the difference is that: the amount of methyl methacrylate was reduced to 10g and the amount of ethyl acrylate was reduced to 5g.
Comparative example 4
The technical scheme adopted is basically the same as that of the embodiment 1, and the difference is that: no polyene monomer is added: divinylbenzene.
Test case
The plugging agent prepared in each example was subjected to the following performance evaluation:
(1) Influence of oil-based drilling fluid plugging agent on rheological property and fluid loss of oil-based drilling fluid base slurry
Preparing oil-based drilling fluid base slurry:
The basic formula comprises the following components: oil-water ratio (white oil: caCl 2 aqueous solution=8:2) +2% primary emulsifier+1.5% secondary emulsifier+3% organoclay+3% cao.
Adding 16g of CaCl 2 into 80ml of water to prepare a CaCl 2 water solution with the mass fraction of 20%; 320ml of white oil is taken and added into a stirring cup, 8g of main emulsifier, 6g of auxiliary emulsifier, 12gCaO g of organic soil and CaCl 2 solution prepared before are added into the stirring cup, and stirring is carried out for 40min at a stirring speed of 6000r/min, so as to prepare the oil-based drilling fluid base slurry.
Preparing drilling fluid samples: 10 parts of 400ml of the drilling fluid base slurry were poured into a stirring cup, 4g of the plugging agent provided in the above example and 4g of the comparative example provided in the comparative example were added thereto, and stirred at 7000r/min for 20min, so that the drug was sufficiently dissolved in the drilling fluid base slurry.
Testing the performance of the normal-temperature drilling fluid base slurry: the rheological parameters and demulsification voltages of the prepared drilling fluid samples were tested according to GB/T16783.2-2012, the normal temperature and pressure fluid loss (FL API) was tested according to GB/T16783.1-2014, and the experimental results are shown in Table 1.
(2) Property change of drilling fluid sample after high temperature treatment
Aging treatment of drilling fluid: drilling fluid samples are respectively filled into different ageing tanks, and hot rolled for 16 hours in a roller furnace at 220 ℃.
Performance test after aging: after aging, taking out and cooling to normal temperature, stirring for 40min at a stirring speed of 6000r/min, testing rheological parameters, high-temperature high-pressure fluid loss (FL HTHP) and demulsification voltage of the aged drilling fluid sample according to GB/T16783.2-2012, wherein the high-temperature high-pressure fluid loss testing condition is that the temperature is 200 ℃ and the pressure difference is 3.5MPa, testing normal-temperature normal-pressure fluid loss (FL API) according to GB/T16783.1-2014, and the experimental results are shown in Table 2.
(3) Medium pressure sand bed experiment
The depth of penetration of the medium pressure sand bed of the drilling fluid sample before and after aging (aging for 16 hours in a roller furnace at 220 ℃) was measured, sand of 120-140 meshes was poured into a cylindrical perspective drilling fluid cup, the mixture was laid flat, the drilling fluid sample before aging (after aging) was poured into the drilling fluid cup, the test pressure was 0.6MPa, and the maximum penetration depth was measured for 30 minutes, and the experimental results are shown in Table 3.
(4) Breakthrough pressure determination
The breakthrough pressure of the drilling fluid samples before and after aging (aging for 16 hours in a roller oven at 220 ℃) was determined. In the measuring process, a constant flow pump is used for driving a drilling fluid sample, the confining pressure is ensured to be 0.5-1MPa higher than the pumping pressure all the time, the displacement rate is 1mL/min, and when the drilling fluid continuously flows out, the pumping pressure at the moment is the breakthrough pressure. The breakthrough pressures of the drilling fluid samples of the examples and comparative examples before aging are shown in Table 4, and the breakthrough pressures of the drilling fluid samples of the examples and comparative examples after aging are shown in Table 5.
The addition amounts of the blocking agents in the tables below are all mass volume percentages, taking "base stock+1% example 1" as an example, i.e. 100ml of base stock requires the addition of 1g of the blocking agent provided in example 1.
TABLE 1
From table 1, it can be seen that the samples of the examples are added into the drilling fluid base slurry, the viscosity and the shear force are both increased, the normal temperature and pressure fluid loss (FL API) is obviously reduced, and the demulsification voltage is obviously increased, which indicates that the plugging agent can effectively improve the performance of the drilling fluid. The higher viscosity and lower fluid loss of the examples compared to the comparative examples indicate that each experimental drug in the synthesis has a greater impact on the performance of the oil-based drilling fluid plugging agent. Compared with the embodiment 1, the increase of the addition amount of the high-temperature-resistant cross-linking agent in the embodiment 2 can effectively increase the viscosity of drilling fluid samples, reduce the fluid loss and increase the demulsification voltage, which shows that the high-temperature-resistant cross-linking agent can enhance the performance of the plugging agent. Example 5 the amount of the polyene monomer divinylbenzene was changed, and it was found that increasing the amount of divinylbenzene increased the viscosity of the samples and decreased the fluid loss. The amounts of styrene, ester monomers (methyl methacrylate and ethyl acrylate) were changed in examples 3 and 4, respectively, and the rheological parameters and the fluid loss were changed to some extent. Example 6 changed the amount of emulsifier, and compared with example 1, the rheological parameters and normal temperature and pressure fluid loss of drilling fluid samples did not change significantly, indicating that a small amount of emulsifier change did not have a significant effect on the performance of the synthetic plugging agent.
In comparative example 1, compared with example 1, it is obvious that the rheological parameter and demulsification voltage value of the drilling fluid sample are obviously reduced, and the fluid loss is increased, which indicates that the high temperature-resistant crosslinking agent has a larger influence on the performance of the plugging agent at normal temperature and normal pressure, and firstly, the plugging agent can prevent coalescence of liquid drops, so that the stable demulsification voltage of the emulsion is increased; secondly, the high-temperature-resistant crosslinking agent can lightly crosslink the single-molecule polymer in the polymerization reaction, and the molecular weight and the rigidity of a molecular structure are increased, so that the viscosity can be effectively increased, and the filtration loss can be reduced. Compared with the embodiment 1, the addition of the ester monomer is reduced by half in the comparative example 3, the viscosity of the drilling fluid sample is reduced by the filtration loss, but the change is smaller, which shows that the addition of the ester monomer has a certain influence on the performance of the plugging agent, but the free movement of a polymer molecular chain can be effectively limited due to the existence of the high-temperature-resistant crosslinking agent and the polyene monomer, and the crosslinking degree of the polymer is improved, so that the performance of the plugging agent is maintained. As can be seen from comparative examples 1 and 4, the drilling fluid samples without the nano-crosslinker and with the organic crosslinker divinylbenzene have larger rheological parameters, fluid loss and breaking voltage than those of example 1, which shows that the high temperature-resistant crosslinker has larger influence on the performance of the plugging agent, and the crosslinking effect of the high temperature-resistant crosslinker is larger than that of the common organic crosslinker.
TABLE 2
As can be seen from table 2, after 220 ℃ hot roll aging, the rheological and normal temperature and pressure fluid loss (FL API) parameters of the drilling fluid sample were significantly changed: the viscosity is reduced, the fluid loss is increased, the demulsification voltage is reduced, but the basic performance of the embodiment added with the plugging agent product is obviously better than that of the base slurry, which shows that the plugging agent polymer can be degraded at high temperature to a certain extent, but the drilling fluid performance can be obviously improved, and the excellent high-temperature plugging resistance is shown. Compared with the embodiment 1, the embodiment 2 increases the addition amount of the high-temperature-resistant cross-linking agent, so that the viscosity of a drilling fluid sample can be obviously increased, the fluid loss is reduced, and the demulsification voltage is improved; in comparative example 1, the rheological parameter, the fluid loss and the demulsification voltage data of the drilling fluid sample are basically similar to those of the base slurry measured data without adding the high-temperature-resistant cross-linking agent; the high-temperature-resistant cross-linking agent has an important effect on improving the high-temperature resistance of the plugging agent, and the high-temperature-resistant cross-linking agent can moderately cross-link a single-molecule polymer, so that the high-temperature resistance of the plugging agent can be effectively improved. Compared with example 1, the styrene in example 3 is increased to 40g, the rheological parameter, the fluid loss and the demulsification voltage of the drilling fluid sample are obviously changed, but the performance of the sample in example 3 before aging is not obviously changed, which indicates that the benzene ring structure is introduced into the synthesized plugging agent, so that the thermal stability of polymer molecules can be increased, and the plugging agent has a certain high temperature resistance. The addition of styrene was reduced to 10g in comparative example 2 and the properties of the drilling fluid samples were better than the base slurry properties, indicating that moderate crosslinking during polymerization could significantly improve the temperature and hydrolysis resistance of the polymer.
High temperature and high pressure fluid loss (FL HTHP) was measured at 200℃and 3.5MPa pressure differential, and as shown in Table 2, FL HTHP in the examples was less than 12.8mL of the base slurry, indicating that the plugging agent was significantly effective. The data in the examples are significantly better than the data in the base slurry and comparative examples, and the FL HTHP in example 2 is reduced to 8.2mL, indicating that the plugging agent not only has good temperature resistance, but also has excellent pressure-bearing characteristics.
TABLE 3 Table 3
| Sample name | Immersion depth/cm of sand bed before aging | Immersion depth/cm of sand bed after aging |
| Base slurry | 6.2 | 7.8 |
| Base stock +1% example 1 | 4.4 | 5.6 |
| Base stock +1% example 2 | 3.4 | 4.0 |
| Base stock +1% example 3 | 3.8 | 4.6 |
| Base stock +1% example 4 | 4.0 | 5.2 |
| Base stock +1% example 5 | 3.4 | 4.8 |
| Base stock +1% example 6 | 4.4 | 5.4 |
| Base slurry +1% comparative example 1 | 5.8 | 7.0 |
| Base slurry +1% comparative example 2 | 5.0 | 6.8 |
| Base stock +1% comparative example 3 | 5.0 | 6.0 |
| Base stock +1% comparative example 4 | 5.6 | 6.6 |
As can be seen from Table 3, according to the comparison of the properties of the drilling fluid samples of the examples with the base slurry and the comparative examples, the immersion depth of the sand bed before and after aging is obviously reduced after the nano plugging agent is added, which indicates that the nano high temperature resistant plugging agent can effectively plug microcracks/pores of the sand bed under the conditions of normal temperature and high temperature, and reduces the immersion depth of the drilling fluid in the sand bed. As can be seen from the embodiment 2 and the comparative example 1, the immersion depth of the sand bed before and after aging can be remarkably reduced by increasing the addition amount of the high-temperature-resistant cross-linking agent; otherwise, if the high-temperature-resistant cross-linking agent is not added, the sand bed of the drilling fluid sample is 5.8cm and 6.8cm before and after immersion depth aging respectively, the performance of the drilling fluid sample and the base slurry are relatively close, and the effect is poor. As can be seen from the example 3 and the comparative example 2, the immersion depth of the sand bed before aging of the drilling fluid sample is ideal after the addition of the styrene is reduced to 10g, but the immersion depth of the sand bed after aging reaches 6.8cm, so that the effect is extremely poor; when the addition amount of the styrene reaches 40g, the immersion depth of the sand bed before and after aging is obviously reduced compared with that of the comparative example 2; because the benzene ring structure is introduced into the synthesized plugging agent, the benzene ring has better thermal stability, and the thermal movement of molecular chains can be greatly hindered under the high-temperature condition, so that the proper amount of styrene is increased in the process of synthesizing the plugging agent, which is very important for improving the performance of the plugging agent.
TABLE 4 Table 4
| Sample name | Core permeability/10 -3μm2 | Breakthrough pressure/MPa |
| Base slurry | 115.3 | 0.5 |
| Base stock +1% example 1 | 108.6 | 5.2 |
| Base stock +1% example 2 | 111.2 | 6.8 |
| Base stock +1% example 3 | 114.5 | 6.2 |
| Base stock +1% example 4 | 106.8 | 5.8 |
| Base stock +1% example 5 | 107.5 | 6.2 |
| Base stock +1% example 6 | 112.5 | 5.2 |
| Base slurry +1% comparative example 1 | 113.7 | 2.3 |
| Base slurry +1% comparative example 2 | 108.9 | 3.8 |
| Base stock +1% comparative example 3 | 107.8 | 5.2 |
| Base stock +1% comparative example 4 | 105.4 | 4.3 |
As can be seen from table 4, the core permeability is selected to be substantially between 105-116×10 -3μm2, so that the core permeability does not have a significant effect on the experimental results. As can be seen from the comparison of the breakthrough pressures of the examples and the base slurry and the drilling fluid samples of the comparative examples, the pump pressure required for the drilling fluid to break through the core is significantly increased after the nano plugging agent is added, which indicates that the nano plugging agent can effectively plug micro-cracks, micro-pores and smaller flow channels in the core, and plug a larger part of micro-nano cracks and pores with smaller size in the core.
TABLE 5
| Sample name | Core permeability/10 -3μm2 | Breakthrough pressure/MPa |
| Base slurry | 110.6 | 0.3 |
| Base stock +1% example 1 | 112.5 | 4.2 |
| Base stock +1% example 2 | 108.7 | 6.2 |
| Base stock +1% example 3 | 109.4 | 5.6 |
| Base stock +1% example 4 | 106.3 | 4.8 |
| Base stock +1% example 5 | 113.4 | 5.2 |
| Base stock +1% example 6 | 111.2 | 4.4 |
| Base slurry +1% comparative example 1 | 109.4 | 1.6 |
| Base slurry +1% comparative example 2 | 106.4 | 3.2 |
| Base stock +1% comparative example 3 | 113.4 | 4.2 |
| Base stock +1% comparative example 4 | 111.5 | 3.0 |
As can be seen from Table 5, the breakthrough pressures of the drilling fluid samples of the examples and comparative examples were reduced to different extents after aging, but the amount of change was small, indicating that the sealant polymer was slightly degraded and hydrolyzed at high temperatures, but the performance of the sealant was not greatly affected. As can be seen from the comparison of the breakthrough pressures of the examples and the base slurry and the drilling fluid samples of the comparative examples, the breakthrough pressure in the examples is significantly improved after the addition of the nano plugging agent, which indicates that the performance of the nano plugging agent is not greatly affected under the high temperature condition. Compared with the example 2 before aging, the breakthrough pressure of the example 2 after aging is only reduced by 0.6MPa, and the reduction rate is only 8.8%, which indicates that the high-temperature-resistant cross-linking agent can lightly cross-link a single-molecule polymer in the process of synthesizing the plugging agent polymer, and the cross-linking structure can keep the basic structure of the cross-linking agent not damaged under the high-temperature condition, and has good temperature resistance. Compared with the example 1, the addition amount of the styrene is increased in the example 3, the breakthrough pressure is increased to 5.6MPa, and the benzene ring structure is introduced in the process of synthesizing the plugging agent polymer, so that the thermal stability and the rigidity of the polymer can be increased; because of the rigid benzene ring structure and the toughness of the high polymer, the drilling fluid cannot leak under the condition of larger liquid column pressure difference. The comparison shows that the base slurry containing the nano plugging agent can still maintain excellent plugging capability under a larger pressure difference after aging, and has very high temperature resistance and better pressure bearing capability.
The experimental results show that the oil-based drilling fluid plugging agent provided by the embodiment of the invention has the following remarkable advantages: firstly, a high-temperature-resistant cross-linking agent is adopted in the process of synthesizing the plugging agent, the high-temperature-resistant cross-linking agent can lightly cross-link a single-molecule polymer, and the cross-linked structure can keep the basic structure of the single-molecule polymer undamaged under the high-temperature condition, so that the single-molecule polymer has good temperature resistance. And secondly, a benzene ring structure is introduced in the synthesis process, the particle size of the synthesized plugging agent is in a nanoscale, and the nanoparticle and the benzene ring structure have high thermal stability and rigidity, so that the plugging agent has a certain promotion effect on the high temperature resistance and the pressure bearing capacity of the plugging agent. Finally, as the particle size of the plugging agent is in the nanometer level, the plugging agent can effectively plug microcracks/pores in the rock and prevent drilling fluid from flowing into stratum rock.
In embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" refers to two or more, unless explicitly defined otherwise.
The foregoing description is only for the convenience of those skilled in the art to understand the technical solution of the present invention, and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. The preparation method of the oil-based drilling fluid plugging agent is characterized by comprising the following steps of:
the method comprises the steps of (1) placing divinyl dimethyl silane and diphenyl chloromethane in a first reactor, and dropwise adding a catalyst into the first reactor under the conditions of rotating speed of 180 r/min-250 r/min and temperature of 50-75 ℃;
After the catalyst is added dropwise, heating a reaction system to 80-95 ℃, and then adding an initiator into the first reactor;
increasing the rotating speed to 300r/min-350r/min, and performing reaction for a set time to obtain a crosslinking agent;
Adding an emulsifying agent into a second reactor filled with deionized water in advance, then continuously adding the crosslinking agent into the second reactor, uniformly stirring, continuously adding a high-temperature resistant monomer, an ester monomer and a polyene monomer into the second reactor, and uniformly stirring to obtain a pre-emulsion;
In the presence of an initiator, carrying out polymerization reaction on the pre-emulsion to obtain the oil-based drilling fluid plugging agent;
Wherein the high temperature resistant monomer is at least one selected from styrene, 2-acrylamido-2-methylpropanesulfonic acid, sodium styrenesulfonate and N-vinyl pyrrolidone;
The polyene monomer is at least one of triallyl isocyanurate, divinylbenzene and diallyl diphenyl silane;
wherein the catalyst is tri-n-butylamine, and the mass ratio of the divinyl dimethyl silane to the diphenyl chloromethane is 6-10:1;
The emulsifier is at least one selected from emulsifier OP-10, emulsifier OS and span 80;
The ester monomer is at least one selected from methyl methacrylate, butyl acrylate, ethyl acrylate and 2-methyl methacrylate;
The initiator is at least one selected from ammonium persulfate, potassium persulfate and tert-butyl hydroperoxide.
2. The method for preparing the oil-based drilling fluid plugging agent according to claim 1, wherein the step of polymerizing the pre-emulsion in the presence of an initiator to obtain the oil-based drilling fluid plugging agent comprises the following steps:
transferring the pre-emulsion into a third reactor, adding an initiator into the third reactor under the conditions of introducing nitrogen and stirring, and then reacting for a set time under the condition of 65-85 ℃ to obtain the oil-based drilling fluid plugging agent.
3. An oil-based drilling fluid plugging agent, which is prepared by the preparation method according to any one of claims 1-2.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5465792A (en) * | 1994-07-20 | 1995-11-14 | Bj Services Company | Method of controlling production of excess water in oil and gas wells |
| CN104194750A (en) * | 2014-07-30 | 2014-12-10 | 中国石油天然气集团公司 | Nanometer blocking agent for oil-based drilling fluid and preparation method of nanometer blocking agent |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5465792A (en) * | 1994-07-20 | 1995-11-14 | Bj Services Company | Method of controlling production of excess water in oil and gas wells |
| CN104194750A (en) * | 2014-07-30 | 2014-12-10 | 中国石油天然气集团公司 | Nanometer blocking agent for oil-based drilling fluid and preparation method of nanometer blocking agent |
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