CN106634897B - Emulsion microsphere plugging agent for drilling fluid and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of additives for drilling fluid, and particularly relates to an emulsion microsphere plugging agent for drilling fluid and a preparation method thereof. The blocking agent is obtained by inverse emulsion polymerization of the following components in parts by weight: 70-90 parts of white oil, 5-10 parts of polyglycerol monostearate, 0.5-2 parts of polyoxyethylene sorbitan monooleate, 50-70 parts of N, N-dimethylacrylamide, 100-130 parts of distilled water, 10-15 parts of sodium carbonate, 15-25 parts of acrylic acid, 2-7 parts of vinyltrimethoxysilane, 0.2-0.5 part of a complexing agent, 0.5-1.5 parts of an initiator and 0.02-0.05 part of a chain terminator. The obtained product has a micro-nano core-shell structure, can effectively plug micro cracks with different magnitudes, has good plugging and fluid loss reducing effects, and has a lubricating effect comparable to that of a lubricating agent.

Description

Emulsion microsphere plugging agent for drilling fluid and preparation method thereof

technical field

The invention belongs to the field of additives for drilling fluids, in particular to an emulsion microsphere plugging agent for drilling fluids and a preparation method thereof.

Background technique

Wellbore instability has always been a major problem in the field of oil drilling, which has always existed and has not been well resolved. More than 90% of wellbore instability occurs in shale formations. Wellbore instability not only affects drilling speed, logging and cementing quality, but also makes it impossible to drill to the target layer in some areas, affecting the realization of exploration goals.

For mud shale formations with well-developed bedding and fractures, in order to prevent wellbore instability, the drilling fluid is required to have strong sealing properties, which can effectively seal formation bedding and fractures, prevent drilling fluid and its filtrate from entering the formation, and improve formation performance. Pressure bearing capacity, stable well wall and prevention of lost circulation. However, the existing plugging agents are mainly used in soil slurry to have a better fluid loss reduction effect; for solid-free drilling fluids, common plugging agents (such as: starch, cellulose, resins, etc.) etc.) It is difficult to achieve the effect of reducing fluid loss.

Contents of the invention

The first technical problem to be solved by the present invention is to provide an emulsion microsphere plugging agent for drilling fluid, which is obtained by inverse emulsion polymerization of the following components, in parts by weight, said components include: 70-90 parts of white oil, 5-10 parts of polyglycerol monostearate, 0.5-2 parts of polyoxyethylene sorbitan monooleate, 50-70 parts of N,N-dimethylacrylamide, 100 parts of distilled water ~130 parts, 10~15 parts of soda ash, 15~25 parts of acrylic acid, 2~7 parts of vinyltrimethoxysilane, 0.2~0.5 parts of complexing agent, 0.5~1.5 parts of initiator, 0.02~0.05 parts of chain terminator.

Preferably, in the above-mentioned emulsion microsphere plugging agent for drilling fluid, in parts by weight, the components include: 80 parts of white oil, 7 parts of polyglycerol monostearate, polyoxyethylene sorbitan mono-oil 1 part of acid ester, 60 parts of N,N-dimethylacrylamide, 120 parts of distilled water, 12 parts of soda ash, 20 parts of acrylic acid, 5 parts of vinyltrimethoxysilane, 0.5 part of complexing agent, 1 part of initiator, chain termination 0.05 parts.

Wherein, in the above emulsion microsphere plugging agent for drilling fluid, the complexing agent is disodium edetate, and the chain terminator is sodium nitrite.

Wherein, in the aforementioned emulsion microsphere plugging agent for drilling fluid, the initiator is potassium persulfate or sodium formaldehyde sulfoxylate.

The second technical problem to be solved by the present invention is to provide the preparation method of the above-mentioned emulsion microsphere plugging agent for drilling fluid, the method comprises the following steps:

(1) Preparation of the oil phase: at room temperature, add 70-90 parts of white oil to the reaction kettle, slowly add 5-10 parts of polyglycerol monostearate, polyoxygen 0.5 to 2 parts of ethylene sorbitan monooleate, stirred for 30 to 60 minutes to obtain an oil phase, and set aside;

(2) Water phase preparation:

Add 100-130 parts of distilled water into another reaction kettle, start stirring at a speed of 60-70r/min, slowly add 10-15 parts of soda ash, stir for 20-40 minutes, then slowly add 15-25 parts of acrylic acid, N, N - 50-70 parts of dimethylacrylamide, 2-7 parts of vinyltrimethoxysilane, stirred for 50 minutes to obtain the water phase, and set aside;

(3) Aggregation:

Slowly add the water phase obtained in step (2) into the oil phase obtained in step (1), turn on the cooling water and adjust the speed of the agitator to 100-110r/min and stir for 20-40min, then pass nitrogen gas to deoxygenate for 25-35min , add 0.5-1.5 parts of initiator, 0.2-0.5 parts of complexing agent, react at a constant temperature of 33-37°C for 2.8-3.2h, then raise the temperature to 58-62°C and polymerize for 1.6-2.2h; then close the nitrogen, add 0.02 ~0.05 parts, react for 25~35 minutes to get the final product.

Wherein, in the preparation method of the emulsion microsphere plugging agent for drilling fluid, the complexing agent is disodium edetate, and the chain terminator is sodium nitrite.

Wherein, in the above preparation method of the emulsion microsphere plugging agent for drilling fluid, the initiator is potassium persulfate or sodium formaldehyde sulfoxylate.

The beneficial effects of the present invention are: compared with the ordinary plugging fluid loss reducer, the particle size of the plugging agent of the present invention is in the micronano (≤50 μm) range, and the plugging agent has a core-shell structure, and the elastic core makes it possible to Microscopic plastic deformation occurs, and the peripheral hydrophilic shell ensures the coalescence stability of the plugging agent, thereby effectively sealing micro-cracks of different magnitudes. In addition, the product of the present invention has a good plugging and fluid loss reduction effect, and has a lubricating effect comparable to that of lubricants; and has temperature resistance (180°C) and salt resistance, good compatibility, and is suitable for fresh water and salt water drilling and completion fluids ; At the same time, it also overcomes the danger to personnel caused by the dust generated during the use of solid products.

Detailed ways

The invention provides an emulsion microsphere plugging agent for drilling fluid. The plugging agent is obtained by inverse emulsion polymerization of the following components. In parts by weight, the components include: 70-90 parts of white oil , 5-10 parts of polyglycerol monostearate, 0.5-2 parts of polyoxyethylene sorbitan monooleate, 50-70 parts of N,N-dimethylacrylamide, 100-130 parts of distilled water, 10 parts of soda ash ~15 parts, 15~25 parts of acrylic acid, 2~7 parts of vinyltrimethoxysilane, 0.2~0.5 parts of complexing agent, 0.5~1.5 parts of initiator, 0.02~0.05 parts of chain terminator.

Preferably, in the above-mentioned emulsion microsphere plugging agent for drilling fluid, in parts by weight, the components include: 80 parts of white oil, 7 parts of polyglycerol monostearate, polyoxyethylene sorbitan mono-oil 1 part of acid ester, 60 parts of N,N-dimethylacrylamide, 120 parts of distilled water, 12 parts of soda ash, 20 parts of acrylic acid, 5 parts of vinyltrimethoxysilane, 0.5 part of complexing agent, 1 part of initiator, chain termination 0.05 parts.

Wherein, in the above-mentioned emulsion microsphere plugging agent for drilling fluid, the complexing agent is disodium edetate, the chain terminator is sodium nitrite, and the initiator is potassium persulfate or formaldehyde. sodium bisulfate.

Further, the present invention also provides a preparation method of the above-mentioned emulsion microsphere plugging agent for drilling fluid, the method comprising the following steps:

(1) Oil phase preparation: under normal temperature conditions, add 70-90 parts of white oil into the reaction kettle, slowly add emulsifier polyglycerol monostearate 5-10 parts under stirring condition of 60-70r/min, 0.5 to 2 parts of polyoxyethylene sorbitan monooleate, stirred for 30 to 60 minutes to obtain an oil phase, and set aside;

(2) Water phase preparation:

Add 100-130 parts of distilled water into another reaction kettle, start stirring at a speed of 60-70r/min, slowly add 10-15 parts of soda ash, stir for 20-40 minutes, then slowly add 15-25 parts of acrylic acid, N, N - 50-70 parts of dimethylacrylamide, 2-7 parts of vinyltrimethoxysilane, stirred for 50 minutes to obtain the water phase, and set aside;

(3) Aggregation:

Slowly add the water phase obtained in step (2) into the oil phase obtained in step (1), turn on the cooling water and adjust the speed of the agitator to 100-110r/min and stir for 20-40min, then pass nitrogen gas to deoxygenate for 25-35min , add 0.5-1.5 parts of initiator, 0.2-0.5 parts of complexing agent, react at a constant temperature of 33-37°C for 2.8-3.2h, then raise the temperature to 58-62°C and polymerize for 1.6-2.2h; then close the nitrogen, add 0.02 ~0.05 parts, react for 25~35 minutes to get the final product.

Wherein, in the preparation method of the above-mentioned emulsion microsphere plugging agent for drilling fluid, the complexing agent is disodium edetate, the chain terminator is sodium nitrite, and the initiator is potassium persulfate or Sodium formaldehyde sulfoxylate.

Furthermore, the present invention also provides the application of the emulsified microsphere plugging agent for drilling fluid in solid-free drilling fluid.

The emulsion microsphere plugging agent for drilling fluid prepared by the above method is a kind of plugging fluid loss control agent, which has a good fluid loss control effect in solid-free drilling fluid; this product adopts reverse phase emulsion synthesis technology to ensure sealing The particle size of the plugging agent is in the micronano range (≤50um); the plugging agent has a core-shell structure, the elastic core enables microscopic plastic deformation, and the peripheral hydrophilic shell ensures the coalescence stability of the plugging agent, thus effectively Seal micro-cracks of different magnitudes. This product has a good plugging and fluid loss reduction effect and has a lubricating effect comparable to that of lubricants. It also has temperature resistance (180°C) and salt resistance, and is suitable for drilling and completion fluids in fresh water and salt water.

The present invention will be further explained and illustrated below in conjunction with the examples, and the protection scope of the present invention will not be limited thereby.

Example 1

The emulsion microsphere plugging agent for drilling fluid is prepared according to the following method:

(1) Oil phase preparation:

Under the condition of normal temperature, start the stirring, the rotating speed is 65r/min, add 80 parts of white oil into the reaction kettle, slowly add emulsifier polyglycerol stearate 7 parts, polyoxyethylene sorbitan monooleic acid 1 part of ester, stirred for 45min to obtain the oil phase, set aside;

(2) Water phase preparation:

Add 120 parts of distilled water into another reaction kettle, start stirring at 65r/min, slowly add 12 parts of soda ash, stir for 30 minutes, then slowly add 20 parts of acrylic acid, 60 parts of N,N-dimethylacrylamide, ethylene 5 parts of trimethoxysilane, stirred for 50min to obtain the water phase, set aside;

(3) Aggregation:

Slowly add the water phase obtained in step (2) into the oil phase obtained in step (1), turn on the cooling water and adjust the speed of the agitator to 100r/min and stir at a high speed for 30min, then pass through nitrogen to remove oxygen for 30min, then add the initiator formaldehyde 1 part of sodium bisulfite, 0.5 part of complexing agent disodium ethylenediamine tetraacetate, react at a constant temperature of 35°C for 3 hours, then raise the temperature to 60°C for polymerization for 2 hours, then turn off the nitrogen, add 0.05 part of polymerization terminator sodium nitrite, and react The produced product can be obtained in 30 minutes, then loaded into barrels, sampled and tested, and put into storage.

The products obtained in the above examples (product particle size ≤ 50um) were tested according to conventional testing methods in the art, and the testing results are shown in Table 1.

Table 1. Performance of emulsion microsphere plugging agent for drilling fluid obtained in embodiment

project Indicator requirements Test results Exterior milky white viscous liquid milky white viscous liquid Adhesion coefficient reduction rate ≥40% 56% Normal temperature filtration loss (fresh water) ≤25mL 18mL 180℃ aging filtration loss (fresh water) ≤28mL 17.5mL Filtration loss at room temperature (4wt% brine) ≤25mL 21mL 180°C aging fluid loss (4wt% brine) ≤28mL 19mL

Example 2

In order to investigate the fluid loss reduction effect of the product of Example 1 in the solid-free drilling fluid, the following 6 groups of parallel experiments were done, simulating the solid-free drilling fluid with clear water, adding 2wt% carboxymethylcellulose sodium salt (CMC ), modified starch, sodium polyanion cellulose, lignite resin, embodiment 1 product, investigate wherein pressure filtration loss. The test results are shown in Table 2. It can be seen from Table 2 that the fluid loss control effect of this patented product in solid-free drilling fluid is unparalleled by conventional plugging fluid loss control agents.

Table 2.

serial number project Medium pressure fluid loss 1 clear water lost all 2 Clear water+2wt%CMC lost all 3 Clear water+2wt% modified starch lost all 4 Clear water+2wt% sodium polyanion cellulose lost all 5 Clear water+2wt% lignite resin lost all 6 Clear water+2wt% embodiment 1 product 18mL

The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (4)

1. drilling fluid lotion microballoon sealing agent, which is characterized in that the sealing agent is obtained by the inverted emulsion polymerization of following components, Based on parts by weight, the component includes: 70~90 parts of white oil, and 5~10 parts of polyglycerol monostearate, polyoxyethylene mountain 0.5~2 part of pears alcohol monoleate, 50~70 parts of N,N-DMAA, 100~130 parts of distilled water, soda ash 10~15 Part, 15~25 parts of acrylic acid, 2~7 parts of vinyl front three oxosilane, 0.2~0.5 part of complexing agent, 0.5~1.5 part of initiator, chain 0.02~0.05 part of terminator；

The preparation method of the sealing agent the following steps are included:

(1), oil is mutually prepared: under normal temperature conditions, 70~90 parts of white oil being added in a kettle, 60~70r/min stirring condition 5~10 parts of polyglycerol monostearate, 0.5~2 part of polyoxyethylene sorbitan monooleate are slowly sequentially added down, are stirred 30~60min obtains oily phase, spare；

(2) water phase is prepared: 100~130 parts of distilled water being added in another reaction kettle, opens stirring, revolving speed is 60~70r/ Min is slowly added to 10~15 parts of soda ash, stirs 20~40min, is then successively slowly added to 15~25 parts of acrylic acid, N, N- bis- 50~70 parts of Methacrylamide, 2~7 parts of vinyl front three oxosilane stir 50min, obtain water phase, spare；

(3) it polymerize: the water phase that step (2) obtains is slowly added into oily phase obtained by step (1), opens cooling water blender and turn Velocity modulation is to 100~110r/min and stirs 20~40min, and after then passing to 25~35min of nitrogen deoxygenation, initiator 0.5 is added ~1.5 parts, 0.2~0.5 part of complexing agent, 33~37 DEG C of 2.8~3.2h of isothermal reaction then heat to 58~62 DEG C of polymerizations 1.6 ~2.2h；It is then shut off nitrogen, is added 0.02~0.05 part of polymerization terminator, 25~35min of reaction obtains finished product.

2. drilling fluid according to claim 1 lotion microballoon sealing agent, which is characterized in that based on parts by weight, described Component includes: 80 parts of white oil, and 7 parts of polyglycerol monostearate, 1 part of polyoxyethylene sorbitan monooleate, N, N- diformazan 60 parts of base acrylamide, 120 parts of distilled water, 12 parts of soda ash, 20 parts of acrylic acid, 5 parts of vinyl front three oxosilane, complexing agent 0.5 Part, 1 part of initiator, 0.05 part of chain terminating agent.

3. drilling fluid according to claim 1 or 2 lotion microballoon sealing agent, which is characterized in that the complexing agent is second Edetate disodium, the chain terminating agent are sodium nitrite.

4. drilling fluid according to claim 1 or 2 lotion microballoon sealing agent, which is characterized in that the initiator was Potassium sulfate or sodium formaldehyde sulphoxylate.