阅读说明：本技术 钻井液用成膜剂及其制备方法和应用 (Film-forming agent for drilling fluid and preparation method and application thereof ) 是由 王义虎 李昂 王兴宇 全威 刘涛光 刘敬礼 段利波 高峰 李捷 于 2020-07-15 设计创作，主要内容包括：本发明属于钻井液技术领域,尤其涉及钻井液用成膜剂及其制备方法和应用。该成膜剂由包括如下重量份数的原料制备而得：异佛尔酮二异氰酸酯20-30份、聚己内酯20-30份、扩链剂5-10份、丙烯酸单体20-30份、2-丙烯酰胺基-2-甲基丙磺酸8-15份、助溶剂5-10份、引发剂1-5份、去离子水20-30份。该成膜剂主要用于页岩气钻井中,不仅能够吸附在粘土表面抑制其水化,还可以吸附在岩石表面自发聚合形成一层聚合物膜,起到封堵泥页岩微孔隙和微裂缝,降低次生裂缝发育以及钻井液压力传递的作用。同时,该膜状物阻止钻井液中的固相和液相侵入储层,达到保护储层的目的。(The invention belongs to the technical field of drilling fluid, and particularly relates to a film-forming agent for drilling fluid, and a preparation method and application thereof. The film forming agent is prepared from the following raw materials in parts by weight: 20-30 parts of isophorone diisocyanate, 20-30 parts of polycaprolactone, 5-10 parts of a chain extender, 20-30 parts of an acrylic monomer, 8-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5-10 parts of a cosolvent, 1-5 parts of an initiator and 20-30 parts of deionized water. The film-forming agent is mainly used in shale gas drilling, can be adsorbed on the surface of clay to inhibit the hydration of the clay, and can also be adsorbed on the surface of rock to spontaneously polymerize to form a polymer film, thereby playing the roles of blocking the micropores and microcracks of the clay shale, reducing the development of secondary cracks and reducing the pressure transmission of drilling fluid. Meanwhile, the membrane prevents solid phase and liquid phase in the drilling fluid from invading into a reservoir, thereby achieving the purpose of protecting the reservoir.)

1. The film forming agent for the drilling fluid is characterized by being prepared from the following raw materials in parts by weight: 20-30 parts of isophorone diisocyanate, 20-30 parts of polycaprolactone, 5-10 parts of a chain extender, 20-30 parts of an acrylic monomer, 8-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5-10 parts of a cosolvent, 1-5 parts of an initiator and 20-30 parts of deionized water.

2. The film former as claimed in claim 1 wherein the acrylic monomer comprises at least one of beta-hydroxyethyl acrylate, butyl acrylate, methyl methacrylate, and octadecyl acrylate.

3. The film former as claimed in claim 1 wherein said initiator comprises at least one of potassium persulfate, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride.

4. The film former as claimed in claim 1 wherein the chain extender comprises at least one of dimethylolpropionic acid, 1, 4-butanediol.

5. The film forming agent of claim 1, wherein the co-solvent comprises at least one of ethylene glycol monobutyl ether, isopropyl alcohol.

6. The preparation method of the film forming agent for the drilling fluid, disclosed by any one of claims 1-5, is characterized by comprising the following steps of:

adding polycaprolactone into a reaction kettle, carrying out vacuum dehydration for 2h at 120 ℃, and cooling to 80 ℃;

adding isophorone diisocyanate and a cosolvent, reacting for 3 hours, and cooling to 70 ℃;

adding a chain extender, reacting for 2 hours, cooling to 60 ℃, reacting for 1.5 hours, and cooling to 40 ℃;

adding acrylic monomer and 2-acrylamide-2-methylpropanesulfonic acid, and stirring for 0.5 h;

adding deionized water, emulsifying and dispersing at high speed, adding an initiator, carrying out free radical polymerization at 80 ℃ for 3.5h, cooling and discharging to obtain the film forming agent.

7. The film forming agent for the drilling fluid, which is disclosed by any one of claims 1-5, is applied to drilling of shale gas and coal bed gas.

Technical Field

The invention belongs to the technical field of drilling fluid, and particularly relates to a film-forming agent for drilling fluid, and a preparation method and application thereof.

Background

With the increasing development of drilling technology, high-difficulty wells such as ultra-deep wells, horizontal wells, extended reach wells and the like are becoming the main research direction of oil and gas drilling. Such as shale gas drilling which is gradually increased in recent years, the shale gas drilling is mainly formed in shale and mudstone which are rich in organic matters in an adsorption state and a free state, and is different from the traditional coal bed gas drilling which is formed in a coal bed in an adsorption state. In addition, the development of shale gas is deeper and more complex compared with the coal bed gas burial, the drilling difficulty is higher, the shale gas mainly takes an extended reach well and a horizontal well as the main aspects, the stratum inclination angle is large, the number of folds and faults is large, the stratum is broken, the dark shale stratum is easy to hydrate, expand and collapse, the stratum has the characteristic of micro-crack development, the invasion of external liquid phase caused by capillary self-adsorption is easy to occur, and further the underground complex conditions such as expansion and collapse caused by activity change are caused.

In order to avoid the problems in the drilling process, the conventional drilling fluid usually adopts a plugging agent, the plugging agent is mainly solid particles of various different particles for matching, and the microcracks are temporarily plugged, so that the aim of temporarily plugging the microcracks is fulfilled, however, the microcracks fall off after a long time to cause plugging failure, and water molecules cannot be prevented from entering mud shale, so that the mud shale is hydrated and expanded, and the borehole wall is unstable.

Disclosure of Invention

The film-forming agent provided by the invention can be adsorbed on the surface of clay to inhibit the hydration of the clay, and can also be adsorbed on the surface of rock to spontaneously polymerize to form a polymer film, so that the film-forming agent plays a role in blocking micropores and microcracks of shale, reducing the development of secondary cracks and reducing the pressure transmission of drilling fluid.

The invention provides a film-forming agent for drilling fluid, which is prepared from the following raw materials in parts by weight: 20-30 parts of isophorone diisocyanate, 20-30 parts of polycaprolactone, 5-10 parts of a chain extender, 20-30 parts of an acrylic monomer, 8-15 parts of 2-acrylamido-2-methylpropanesulfonic acid, 5-10 parts of a cosolvent, 1-5 parts of an initiator and 20-30 parts of deionized water.

Further, the acrylic monomer comprises at least one of beta-hydroxyethyl acrylate, butyl acrylate, methyl methacrylate and octadecyl acrylate.

Further, the initiator comprises at least one of potassium persulfate, azobisisobutylamidine hydrochloride and azobisisobutylimidazoline hydrochloride.

Further, the chain extender comprises at least one of dimethylolpropionic acid (DMPA) and 1, 4-Butanediol (BDO).

Further, the cosolvent comprises at least one of ethylene glycol monobutyl ether and isopropanol.

The invention also provides a preparation method of the film forming agent for the drilling fluid, which comprises the following steps:

adding polycaprolactone into a reaction kettle, carrying out vacuum dehydration for 2h at 120 ℃, and cooling to 80 ℃;

adding isophorone diisocyanate (IPDI) and a cosolvent, reacting for 3 hours, and cooling to 70 ℃;

adding a chain extender, reacting for 2 hours, cooling to 60 ℃, reacting for 1.5 hours, and cooling to 40 ℃;

adding acrylic monomer and 2-acrylamide-2-methylpropanesulfonic acid, and stirring for 0.5 h;

adding deionized water, emulsifying and dispersing at high speed, adding an initiator, carrying out free radical polymerization at 80 ℃ for 3.5h, cooling and discharging to obtain the film forming agent.

The invention also provides application of the film-forming agent for the drilling fluid in shale gas drilling.

The invention has the following advantages:

the film-forming agent provided by the invention can be adsorbed on the clay surface to inhibit the hydration of the clay surface, and can also be adsorbed on the rock surface to spontaneously polymerize to form a polymer film, so that the effects of blocking the micropores and microcracks of the shale, reducing the development of secondary cracks and reducing the pressure transmission of drilling fluid are achieved. Meanwhile, the membrane prevents solid phase and liquid phase in the drilling fluid from invading a reservoir, inhibits hydration expansion of the shale, and achieves the purpose of protecting the reservoir. The film forming agent for the drilling fluid can be used for shale gas drilling and has a good film forming effect.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention.

In the drawings:

FIG. 1 is a scanning electron micrograph of a film-forming agent according to example 1 before and after film formation on the surface of filter paper;

wherein, fig. 1(a) is a scanning electron micrograph of the surface of the filter paper, and fig. 1(b) is a film forming of the film forming agent on the surface of the filter paper.

FIG. 2 is a scanning electron micrograph of the film-forming agent of example 1 before and after film formation on the side surface of the filter paper;

wherein, fig. 2(a) is a scanning electron micrograph of the side surface of the filter paper, and fig. 2(b) is a film forming of the film forming agent on the side surface of the filter paper.

FIG. 3 is a scanning electron micrograph of the film-forming agent of example 1 before and after forming a film on the surface of the sandstone;

wherein, fig. 3(a) is the sand surface, and fig. 3(b) is the film forming agent after forming the film on the sand surface.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The embodiment of the invention provides a film-forming agent for drilling fluid, which is prepared from the following raw materials in parts by weight: 20-30 parts of isophorone diisocyanate (IPDI), 20-30 parts of polycaprolactone, 5-10 parts of a chain extender, 20-30 parts of an acrylic monomer, 8-15 parts of 2-acrylamido-2-methylpropanesulfonic Acid (AMPS), 5-10 parts of a cosolvent, 1-5 parts of an initiator and 20-30 parts of deionized water.

The embodiment of the invention adopts IPDI, polycaprolactone and acrylic acid monomers as main components, and the IPDI, the polycaprolactone and the acrylic acid monomers are used together with AMPS, a chain extender and other auxiliaries to prepare the film forming agent. The film forming agent can form a film similar to a chemical 'sealing shell' on the surface of the rock core, and can block micro cracks. The film forming agent has a small structure, can enter the pores of the shale, strongly adsorb or chemically react with the shale to form a substance with a large cementing power, so that mineral particles such as clay and the like are coagulated into a firm whole. Can prevent water and drilling fluid filtrate from entering the stratum, inhibit hydration expansion of the shale and achieve the aim of protecting the reservoir. Meanwhile, the film forming agent in the embodiment of the invention can realize gel breaking and achieve the purpose of improving later-stage drainage and mining.

In an embodiment of the present invention, the acrylic monomer includes at least one of beta-hydroxyethyl acrylate (HEMA), Butyl Acrylate (BA), Methyl Acrylate (MA), Methyl Methacrylate (MMA), and octadecyl acrylate.

In an embodiment of the present invention, the initiator includes at least one of potassium persulfate, azobisisobutylamidine hydrochloride, and azobisisobutylimidazoline hydrochloride.

In an embodiment of the present invention, the chain extender includes at least one of dimethylolpropionic acid (DMPA) and 1, 4-Butanediol (BDO).

In an embodiment of the present invention, the cosolvent includes at least one of ethylene glycol monobutyl ether and isopropyl alcohol.

In one embodiment of the present invention, the molecular weight of polycaprolactone is 10000-.

The embodiment of the invention also provides a preparation method of the film forming agent for the drilling fluid, which comprises the following steps:

adding polycaprolactone into a reaction kettle, carrying out vacuum dehydration for 2h at 120 ℃, and cooling to 80 ℃;

adding isophorone diisocyanate (IPDI) and a cosolvent, reacting for 3 hours, and cooling to 70 ℃;

adding a chain extender, reacting for 2 hours, cooling to 60 ℃, reacting for 1.5 hours, and cooling to 40 ℃;

adding acrylic monomer and 2-acrylamide-2-methylpropanesulfonic acid and stirring for 0.5 h;

adding deionized water, emulsifying and dispersing at high speed, adding water-soluble initiator, free radical polymerizing at 80 deg.C for 3.5h, cooling, and discharging to obtain film-forming agent. In the embodiment of the invention, the film forming agent is milky viscous flowing liquid. The initiator is added in the form of an aqueous solution.

In an embodiment of the present invention, the chain extender is a chain extender subjected to drying and dehydration treatment.

The embodiment of the invention also provides application of the film-forming agent for the drilling fluid in drilling of shale gas and coal bed gas. The film forming agent obtained by the invention can be used for not only coal bed gas but also shale gas. In contrast, shale gas is more deeply buried, more complex, and more difficult to drill than coal bed gas. In the prior art, the drilling fluid is mainly used for coal bed gas drilling, and the film forming agent for the drilling fluid has a good film forming effect in shale gas drilling.

The present invention will be described in detail with reference to examples.