JP2020100675A - Filler and use thereof - Google Patents

Abstract

To provide a filler or the like that can temporarily fill pores even under a high temperature environment.SOLUTION: A filler is powder of a resin composition containing polyurethane resin, the polyurethane resin is at least one of an aliphatic isocyanate polyurethane resin and aromatic isocyanate polyurethane resin, and a sheet-like molding molded from the resin composition has a 23°C durometer type D hardness of 29 or more.SELECTED DRAWING: None

Description

The present invention relates to a sealing agent for temporarily sealing a pit wall and its use.

Oil and gas produced from conventional oil wells and hydrocarbon resources such as shale gas and shale oil, which have been attracting attention in recent years, are generally drilled in rock formations rich in oil and gas. Produced through wells.

For drilling and finishing work of wells, excavation generated from around the drill during well drilling is transported to the ground surface, underground pressure is adjusted to maintain stability inside the well, suppress geological collapse, and A circulating fluid (muddy water or finishing fluid) is used to cool the.

Here, if the reservoir, which is the production layer, is a highly permeable stratum, or if there is a natural fracture (crack) in the shale layer, the fluid will be washed away through the highly permeable strata and the cracks in the well wall, and the circulating mud The volume may decrease and the muddy column pressure may decrease.

As a result, not only is there a risk of destabilizing the inside of the well, reducing the efficiency of drilling and processing work, and causing production failure of the reservoir due to the fluid remaining in the reservoir, as well as highly functional and expensive fluid. There is a possibility that the excavation cost will increase due to the outflow of water. Therefore, in order to suppress the outflow of fluid as much as possible, a method of temporarily sealing the pit wall using a degradable sealing agent is used.

Calcium carbonate or the like is generally used as the eye-blocking agent, but when shifting to production, it is necessary to decompose calcium carbonate, which is the eye-blocking agent, by acid treatment. In addition to the work time required for carrying out this acid treatment, insufficient acid treatment may reduce the amount of resource recovery due to insoluble residues such as residual calcium carbonate, which is a sealing agent.

Therefore, in order to reduce the acid treatment cost while shortening the work time required for the acid treatment and prevent the reduction of the amount of resource recovery due to the remaining of the sealing agent, it is disassembled after a predetermined period and the sealing function is Eye-catching agents using degradable materials that disappear are attracting attention.

Patent Document 1 describes a synthetic resin-containing sealing agent having a sealing function for a period of 40 days or less at a temperature of 93°C (200°F) to 204°C (400°F).

International publication WO2015/072317

With the decrease in the amount of oil and gas recoverable in individual wells and the increase in energy consumption that increases year by year as production progresses, oil development moves from easy locations to more severe locations, and polar areas with severe weather conditions. There is a demand for deep well drilling in the deep water well development area of the ocean. In particular, as the depth of the well increases, the conditions for laying the well become severer. For example, at a high depth of more than about 3000 m in the ground, a high temperature environment of about 110° C. or higher is obtained depending on the location. Therefore, there is a demand for a sealing agent that can be temporarily sealed even in such a high temperature environment.

Further, the fracture has various widths, among them, the width of the crack in the opening or inside of the fracture is several mm or less, or several hundred μm to several μm in the highly permeable stratum, especially around 50 μm. There is a need for a sealing agent that can temporarily seal the narrow pores.

However, Patent Document 1 does not describe any filling agent capable of temporarily filling pores at an appropriate time.

The present invention has been made in view of the above problems, and an object thereof is to provide a sealing agent or the like that can suitably temporarily stop pores that cause loss of drilling fluid even in a high temperature environment. is there.

In order to solve the above-mentioned problems, the present inventors have made earnest studies, and as a result, have reached the following present invention.

The sealing agent according to the present invention is a sealing agent for sealing a pit wall, wherein the sealing agent is a powder of a resin composition containing a polyurethane resin, and the polyurethane resin is an aliphatic isocyanate type. At least one of a polyurethane resin and an aromatic isocyanate-based polyurethane resin, wherein a sheet-like molded article molded from the above resin composition has a durometer type D hardness at 23° C. of 29 or more. ..

Further, in the sealing agent according to the present invention, the aliphatic isocyanate constituting the aliphatic isocyanate-based polyurethane resin comprises hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane diisocyanate. It is preferably at least one aliphatic isocyanate selected from the group.

Further, in the sealing agent according to the present invention, the aromatic isocyanate constituting the aromatic isocyanate polyurethane resin is at least selected from the group consisting of diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate. It is preferably one aromatic isocyanate.

Further, in the sealing agent according to the present invention, at least one of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin preferably contains at least a polyester skeleton.

Moreover, in the sealing agent according to the present invention, the resin composition may further contain a crosslinking agent.

In the sealing agent according to the present invention, the polyurethane resin is composed of the aliphatic isocyanate polyurethane resin, and the weight ratio of the aliphatic isocyanate polyurethane resin to the crosslinking agent is 99.8:0. It is preferably in the range of 2 to 50:50.

Further, in the sealing agent according to the present invention, the polyurethane resin is composed of the aromatic isocyanate polyurethane resin, and the weight ratio of the aromatic isocyanate polyurethane resin and the crosslinking agent is 100:0 to 50: It is preferably in the range of 50.

Further, in the sealing agent according to the present invention, the cross-linking agent is selected from the group consisting of a polyfunctional isocyanate compound, a monomer having an ethylenically unsaturated group, a polyvalent amine, a polyhydric alcohol, and a polyfunctional epoxy compound. It is preferably at least one crosslinking agent.

Further, in the sealing agent according to the present invention, the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin are contained, and the weight ratio of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin is , 80:20 to 0:100 is preferable.

The well fluid according to the present invention is characterized by containing the above-mentioned plugging agent.

Further, the well drilling method according to the present invention is characterized in that the above-mentioned filling agent is used to perform temporary filling.

INDUSTRIAL APPLICABILITY The present invention has an effect of being able to provide a sealing agent or the like capable of temporarily sealing pores even in a high temperature environment.

It is a figure which shows schematically the plug testing machine used for the sealing test by the sealing agent which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described in detail.

<Stopper>
In the present embodiment, the time-degradable-lost circulation materials typically means to temporarily stop the well wall in various steps of well drilling (well laying). For purposes, it refers to the material that is incorporated into the well fluid.

The sealing agent according to the present embodiment is a powder formed from a resin composition having a durometer type D hardness of 29 or more at 23°C. Here, the resin composition contains a polyurethane resin, and the polyurethane resin is at least one of an aliphatic isocyanate polyurethane resin and an aromatic isocyanate polyurethane resin. As will be described later, the aliphatic isocyanate-based polyurethane resin and aromatic isocyanate-based polyurethane resin, which are polyurethane resins, may be crosslinked with a crosslinking agent.

By using a powder formed from such a resin composition as a sealing agent, for example, even in a high temperature environment of 110° C. or higher and 200° C. or lower, a high penetration layer having pores with a width of about 1 μm to 800 μm can be obtained. It can be stopped temporarily.

Since the sealing agent according to the present embodiment is formed of the resin composition having a durometer type D hardness of 29 or more at 23° C., the sealing portion having pores blocked by the sealing agent has If the pressure applied to the stopper cannot be withstood, it deforms or collapses, and the time the stopper is released (stopping time) is 110°C or more and 200°C or less, for example, 1 hour or more and 960 hours (40 days). It can be in the following range. As a result, it is possible to release the plugging by the end of the various works while securing various working times inside and outside the well during the plugging.

[Resin composition]
The resin composition is the main material of the sealing agent. Since the resin composition contains the polyurethane resin and the durometer type D hardness at 23° C. is 29 or more, the well wall can be suitably stopped temporarily in a high temperature environment of 110° C. or more and 200° C. or less. An eye stop agent can be obtained.

The resin composition may have a hardness (durometer type D hardness at 23° C.) of 29 or more. The durometer type D hardness at 23° C. is preferably 29 or more and 80 or less, and more preferably 29 or more and 75 or less. Here, if the sealing agent is too soft, the sealing portion is more likely to disintegrate, and even if it is too hard, the resin composition or the like with reduced strength contained in the sealing agent is discharged from the gap of the sealing portion. It becomes easy to leak. On the other hand, when the durometer type D hardness at 23° C. is in the above-mentioned preferable range, the sealing agent is neither too soft nor too hard, so that the pores are more preferably temporarily stopped at a high temperature. be able to.

The durometer type D hardness of the resin composition is measured using a sheet-shaped molded product formed from the resin composition. The durometer type D hardness can be measured according to ISO7619/JIS K6253. The measurement position of the hardness measuring test piece is 12 mm or more inside from the end of the test piece. When measuring hardness at a plurality of locations, the distance between the measurement points is 6 mm or more. The thickness of the test piece is usually 6 mm or more. As the molded body (test piece) of the resin composition for measuring the durometer type D hardness, two sheets obtained by melt-extruding the resin composition in a sheet form are laminated in accordance with ISO7619/JIS K 6253. It is possible to use the one having 6 mm. When the resin composition is a thermoplastic polyurethane resin, the molded body is a part of the resin composition obtained by melt-kneading the polyurethane resin when producing the sealing agent with a known kneading extruder or the like. Can be sampled and, if necessary, formed into a sheet by using a processing method such as hot pressing. In the case where the resin composition is a thermosetting polyurethane resin, for example, the thermosetting polyurethane resin raw material before curing is poured into a mold for producing a test piece for hardness measurement, and heated to a predetermined temperature after defoaming. Hold for a predetermined time. Thereby, the resin raw material can be cured to obtain a test piece. In addition, before the test, the test piece may be heat-treated at a predetermined temperature for a predetermined time in order to remove mechanical strain during molding and stabilize the hardness, if necessary.

The sealing agent is formed into a powder form by melt-kneading an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin, which are polyurethane resins, and crushing the obtained resin composition. When a cross-linking agent is added to the resin composition, the polyurethane resin containing the cross-linking agent may be melt-kneaded.

The heating temperature and time during melt-kneading may be appropriately adjusted in consideration of the melting points of the aliphatic isocyanate-based polyurethane resin and aromatic isocyanate-based polyurethane resin and the reaction temperature of the crosslinking agent. The eye-blocking agent is obtained by appropriately pulverizing a resin composition obtained by melt-kneading by a known method.

The shape of the particles of the powder formed by the resin composition is not limited, but is spherical, scale-like, plate-like, ellipsoidal, prismatic, rod-like, star-like, polygonal and fibrous. (Short fiber) or the like, or may be porous with small pores. Further, of these, a combination of those having different shapes and a combination of those having different particle sizes may be used.

The melt-kneaded resin composition may be pulverized into powder by freeze pulverization, for example. This makes it possible to obtain a sealing agent in which the median diameter of the particles formed from the resin composition is small.

The powder formed by the resin composition, that is, the sealing agent, has a median diameter (50% D) of preferably 50 μm or more and 800 μm or less, more preferably 100 μm or more and 750 μm or less, and 300 μm or more and 700 μm or less. Is more preferable. Here, when powder is formed using a resin composition having a low durometer type D hardness, the median diameter (50% D) of the powder is preferably larger within the above range.

Further, when the powder is formed by using the resin composition having a high durometer type D hardness, the median diameter (50% D) is preferably smaller within the above range. The resin composition or the like having reduced strength is less likely to leak from the sealing portion, and the pores can be more suitably temporarily sealed at high temperature.

When using a sealing agent, it is preferable to prepare several kinds of powders having different median diameters and to mix and use them. Here, the median diameter of each powder to be mixed is within the above range. It is more preferable that As a result, it is possible to obtain a sealing agent that can more appropriately seal the pores.

[Polyurethane resin]
The sealing agent is formed from a resin composition prepared by using a polyurethane resin as a base resin of the resin composition and having a durometer type D hardness at 23° C. of 29 or more.

Polyurethane resin generally refers to a polymer compound derived from an isocyanate compound with or without a urethane bond. Specifically, it is a polymer compound composed of a urethane bond, and in some cases, a chemical bond such as a urea bond or an amide bond. Examples of the polyurethane resin include thermoplastic polyurethane resin and thermosetting polyurethane resin.

The thermoplastic polyurethane resin and the thermosetting polyurethane resin can be formed from an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin. Therefore, in the present specification, when simply described as “polyurethane resin”, the “polyurethane resin” includes “thermoplastic polyurethane resin” and “thermosetting polyurethane resin”, and “aliphatic isocyanate-based polyurethane resin”. , And “aromatic isocyanate-based polyurethane resin”.

The thermoplastic polyurethane resin is a polyurethane resin that can be repeatedly brought into a molten state by heating, and is a polyurethane resin having a branched structure among aliphatic isocyanate-based polyurethane resin and aromatic isocyanate-based polyurethane resin. Although it may exist, a polyurethane resin having a linear structure is more preferable.

Further, the thermosetting polyurethane resin is a polyurethane resin obtained by curing a prepolymer in a molten state by heating. More specifically, it is a polyurethane resin that can be obtained by crosslinking a thermoplastic polyurethane resin or a prepolymer of a polyurethane resin with a crosslinking agent. Examples of the thermosetting polyurethane resin include those obtained by a molding processing method such as (i) to (iii) below.
(I) Millable gum mold processing method For example, a hydroxyl group-terminated prepolymer having a skeleton such as polyester polyol and a structure derived from an aliphatic isocyanate or an aromatic isocyanate is produced, and a cross-linking agent is kneaded by roll kneading, It can be obtained by putting it in a mold and heating it to promote crosslinking.
(Ii) Cast Molding Method For example, after producing an isocyanate group-terminated prepolymer having a skeleton such as a polyester polyol and a structure derived from an aliphatic isocyanate or an aromatic isocyanate, and adding a crosslinking agent thereto It is obtained by pouring a liquid mixture into a mold and connecting the ends by chain extension or crosslinking.
(Iii) Thermoplastic molding method For example, it is obtained by melting pellets of a thermoplastic polyurethane resin by heating and performing extrusion molding or injection molding. Further, a partially cross-linked polyurethane resin can be obtained by adding a cross-linking agent as needed during melting. Further, if necessary, the thermoplastic polyurethane resin to which a crosslinking agent is added is heat-treated at a predetermined temperature for a predetermined time, whereby crosslinking can be promoted and hardness can be adjusted.

[Adjustment of hardness]
The durometer type D hardness of the resin composition is determined by at least one method of (1) combination of a plurality of polyurethane resins, (2) cross-linking with a cross-linking agent, and heat treatment of the polyurethane resin with the cross-linking agent added (3) electron beam irradiation. Adjusted.

(1) Combined Use of Plural Polyurethane Resins In one embodiment, the durometer type D hardness of the resin composition can be adjusted by jointly using plural polyurethane resins having different hardnesses.

Here, the aliphatic isocyanate-based polyurethane resin generally has low hardness and a high decomposition rate. Further, the aromatic isocyanate-based polyurethane resin has a higher hardness and a lower decomposition rate than the aliphatic isocyanate-based polyurethane resin.

The weight ratio of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin is preferably in the range of 80:20 to 0:100, more preferably in the range of 75:25 to 40:60. , 70:30 to 55:45 is more preferable. Thereby, the durometer type D hardness of the resin composition can be suitably adjusted so as to be within a predetermined range. Therefore, in a high temperature environment of 110° C. to 200° C., it is possible to preferably manufacture a sealing agent capable of temporarily sealing the pit wall.

Here, when the sealing agent contains an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin, the sealing retention time is the sealing maintenance time of the aliphatic isocyanate-based polyurethane resin having a low hardness, and the hardness. Of the aromatic isocyanate-based polyurethane resin having a high temperature. The term "stoppage retention time" used herein means that the stoppage portion in which the pores are stopped by a stoppage agent cannot withstand the pressure applied to the stoppage, and is deformed or collapsed until the stoppage is released. It means the time. The reason why the resin composition cannot withstand pressure is, for example, that hydrolysis or thermal decomposition lowers the strength and molecular weight of the above-mentioned resin composition contained in the sealing agent with time.

Therefore, by changing the mixing ratio of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin in the sealing agent, it becomes possible to adjust the sealing retention time. That is, it is possible to adjust the stoppage maintenance time suitable for the situation when excavating the well.

For example, when a thermosetting polyurethane resin is used as the resin composition, the weight ratio of the prepolymer containing a structure derived from an aliphatic isocyanate and the prepolymer containing a structure derived from an aromatic isocyanate is 80: The durometer type D hardness of the resin composition may be adjusted by mixing so as to be in the range of 20 to 0:100 and allowing crosslinking to proceed with a crosslinking agent described later (millable gum mold molding method or cast mold molding). Processing method).

[Aliphatic isocyanate-based polyurethane resin]
The aliphatic isocyanate-based polyurethane resin is a polyurethane resin having a structure derived from an acyclic or cyclic aliphatic isocyanate. That is, in the present specification, the “aliphatic isocyanate-based polyurethane resin” is defined by the fact that the isocyanate for producing the polyurethane resin is the “aliphatic isocyanate”. That is, the “aliphatic isocyanate-based polyurethane resin” is not defined depending on whether or not the skeleton such as the polyester skeleton constituting the main chain of the polyurethane resin has the “aliphatic” hydrocarbon skeleton.

The aliphatic isocyanate-based polyurethane resin is a polyurethane resin produced by using an aliphatic isocyanate, and the aliphatic isocyanate typically includes an aliphatic diisocyanate. Here, examples of the aliphatic diisocyanate include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), norbornane diisocyanate (NBDI), hydrogenated xylylene diisocyanate (H6XDI), and dicyclohexylmethane diisocyanate. The aliphatic isocyanate-based polyurethane resin may contain an aliphatic diisocyanate and an isocyanurate compound (trimer) of these aliphatic diisocyanates in combination. Among them, the aliphatic isocyanate is more preferably hexamethylene diisocyanate (HDI). In addition, in this specification, the aliphatic isocyanate type polyurethane resin produced using hexamethylene diisocyanate (HDI) may be called a hexamethylene diisocyanate type polyurethane resin (HDI type polyurethane resin).

Examples of the skeleton that constitutes the main chain of the aliphatic isocyanate-based polyurethane resin include a polyether skeleton, a polyester skeleton, a polyether ester skeleton, and a poly(meth)acrylate skeleton. These skeletons are aliphatic isocyanate-based polyurethanes. It may coexist as the main chain of the resin. Among them, the skeleton constituting the main chain of the aliphatic isocyanate-based polyurethane resin is either or both of a polyester skeleton and a polyether ester skeleton, from the viewpoint that desired hardness and hydrolyzability can be obtained. Is preferred. In particular, a polyol containing a polyester skeleton or a polyether ester skeleton is called a polyester polyol, and contains at least an ester skeleton. For example, by reacting a polyester polyol with an aromatic isocyanate, an aromatic isocyanate suitable as a sealing agent is obtained. A polyurethane resin is obtained.

Here, the polyester skeleton is not limited, but is formed by ring-opening polymerization of glycolide, α-acetolactone, β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone and the like. Skeletons, dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, and phthalic acid, and ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,6- It may be a skeleton formed by condensation with a diol such as hexanediol, or a skeleton formed by combining these.

Further, the polyether ester skeleton may be a copolymer of a polyether constituent unit having 1 to 6 carbon atoms in the repeating unit and a polyester constituent unit having 2 to 20 carbon atoms in the repeating unit. Here, examples of the polyether constitutional unit include polyacetal, polyethylene glycol and polytetramethylene glycol, and examples of the polyester constitutional unit include the above polyester skeleton.

The weight average molecular weight of the aliphatic isocyanate-based polyurethane resin is preferably 10,000 or more and 250,000 or less, more preferably 50,000 or more and 200,000 or less, and 100,000 or more, Most preferably, it is 150,000 or less. When the weight average molecular weight of the aliphatic isocyanate-based polyurethane resin is 10,000 or more and 250,000 or less, a sealing agent having appropriate hydrolyzability can be obtained.

As the aliphatic isocyanate-based polyurethane resin, those represented by the following chemical formula (I) are typically preferable.

Here, in the chemical formula (I), m is an integer of 1 or more and 10 or less, and n is an integer of 20 or more and 130 or less.

Examples of the aliphatic isocyanate-based polyurethane resin products include Pandex (registered trademark) T-R3080 manufactured by DIC Covestropolymer Co., Ltd., and the like.

Further, the isocyanate-terminated, hydroxyl-terminated or carboxyl-terminated prepolymer capable of forming these aliphatic isocyanate-based polyurethane resins can be preferably used for obtaining a thermosetting polyurethane resin.

[Aromatic isocyanate-based polyurethane resin]
The aromatic isocyanate-based polyurethane resin is a polyurethane resin having a structure derived from an isocyanate having an aromatic ring. That is, in the present specification, the “aromatic isocyanate-based polyurethane resin” is defined by the fact that the isocyanate for producing the polyurethane resin is the “aromatic isocyanate”. That is, the “aromatic isocyanate-based polyurethane resin” is not defined by whether or not the skeleton such as the polyester skeleton constituting the main chain of the polyurethane resin has the “aromatic” hydrocarbon skeleton.

The aromatic isocyanate-based polyurethane resin is a polyurethane resin produced using an aromatic isocyanate, and the aromatic isocyanate typically includes an aromatic diisocyanate. Here, examples of the aromatic diisocyanate include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and naphthalene diisocyanate (NDI). The aromatic isocyanate-based polyurethane resin may contain an aromatic diisocyanate and an isocyanurate compound (trimer) of these aromatic diisocyanates in combination. Among them, the aromatic isocyanate is more preferably diphenylmethane diisocyanate (MDI). In this specification, an aromatic isocyanate-based polyurethane resin produced by using diphenylmethane diisocyanate (MDI) may be referred to as a diphenylmethane diisocyanate-based polyurethane resin (MDI-based polyurethane resin).

The skeleton that constitutes the main chain of the aromatic isocyanate-based polyurethane resin has a polyether skeleton, a polyester skeleton, a polyether ester skeleton, and a poly(meth)acrylate skeleton, like the skeleton that constitutes the main chain of the aliphatic isocyanate-based polyurethane resin. Etc., but detailed description is omitted.

The weight average molecular weight of the aromatic isocyanate-based polyurethane resin is preferably 5,000 or more and 100,000 or less, more preferably 10,000 or more and 70,000 or less, and 15,000 or more, Most preferably, it is 50,000 or less. When the weight average molecular weight of the aromatic isocyanate-based polyurethane resin is 5,000 or more and 100,000 or less, a sealing agent having appropriate hydrolyzability can be obtained.

As the aromatic isocyanate-based polyurethane resin, those represented by the following chemical formula (II) are typically preferable.

Here, in the chemical formula (II), m is an integer of 1 or more and 10 or less, and n is an integer of 5 or more and 40 or less.

Examples of the MDI-based polyurethane resin product represented by the chemical formula (II) include Pandex (registered trademark) T-5070 manufactured by DIC Covestropolymer Co., Ltd., and the like.

Further, the isocyanate-terminated, hydroxyl-terminated or carboxyl-terminated prepolymer capable of forming these aromatic isocyanate-based polyurethane resins can be preferably used to obtain a thermosetting polyurethane resin.

(2) Crosslinking with Crosslinking Agent In one embodiment, the sealing agent mixes the crosslinking agent with the resin composition to adjust the durometer type D hardness at 23° C. of the resin composition.

The cross-linking agent is preferably at least one cross-linking agent selected from the group consisting of polyfunctional isocyanate compounds, monomers having an ethylenically unsaturated group, polyvalent amines, polyhydric alcohols, and polyfunctional epoxy compounds. Further, a network-like crosslinked structure can be formed in the polyurethane resin by a combination of a plurality of these. Therefore, the hardness of the resin composition can be adjusted appropriately.

As described above, the crosslinking agent may be added to the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin (thermoplastic molding method), and in addition to the prepolymer for forming these polyurethane resins. Good (Millable gum molding method and cast molding method).

(2.1) Polyfunctional isocyanate compound The resin composition may contain a polyfunctional isocyanate compound as a crosslinking agent. The polyfunctional isocyanate compound is a functional compound having an active hydrogen present at the terminal or main chain of these polyurethane resins when melt kneading either or both of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin. Crosslink to the base (thermoplastic molding method).

Examples of the polyfunctional isocyanate compound include the above-mentioned aliphatic diisocyanates and aromatic diisocyanates, and isocyanurates formed from these aliphatic diisocyanates or aromatic diisocyanates.

As an example of the polyfunctional isocyanate compound, as shown in the following general formula (III), the isocyanate group has an allophanate bond with a urethane bond existing in the main chain of the polyurethane resin.

Thereby, the main chain of one polyurethane resin and the main chain of another polyurethane resin are crosslinked via the polyfunctional isocyanate compound. When the polyurethane resin has a urea bond, the polyfunctional isocyanate can form a burette bond with the urea bond. Even by such a buret bond, the polyfunctional isocyanate compound crosslinks the main chain of one polyurethane resin and the main chain of another polyurethane resin through the polyfunctional isocyanate compound.

When the cross-linking agent is added to the aliphatic isocyanate-based polyurethane resin, the weight ratio of the aliphatic isocyanate-based polyurethane resin before addition and the cross-linking agent is in the range of 99.8:0.2 to 50:50. Thus, it is preferable to add a crosslinking agent. The weight ratio of the aliphatic isocyanate-based polyurethane resin to the cross-linking agent is more preferably added so as to be in the range of 99.7:0.3 to 60:40, and 99.6:0.4 to 70: It is more preferable to add it in the range of 30. By adding the crosslinking agent within the above range, the hardness of the crosslinked aliphatic isocyanate polyurethane resin can be further increased. Therefore, in a high temperature environment, it is possible to obtain a sealing agent that can more preferably temporarily seal the pores. When a cross-linking agent is added to the prepolymer of the aliphatic isocyanate polyurethane resin, the weight ratio of the pre-polymer and the cross-linking agent should be in the range of 99.8:0.2 to 50:50. It is preferable to add a cross-linking agent to (millable gum mold processing method). That is, the preferable range of the weight ratio of the prepolymer and the crosslinking agent is in accordance with the preferable range of the weight ratio of the aliphatic isocyanate polyurethane resin and the crosslinking agent.

When the crosslinking agent is added to the aromatic isocyanate-based polyurethane resin, the weight ratio of the aromatic isocyanate-based polyurethane resin before the addition to the crosslinking agent should be in the range of 100:0 to 50:50. It is preferable to add a crosslinking agent. It is preferable that the aromatic isocyanate polyurethane resin and the cross-linking agent are added in a weight ratio of 99.7:0.3 to 60:40, preferably 99.6:0.4 to 70:30. It is more preferable to add it so as to be within the range. By adding the crosslinking agent in the above range, the hardness of the crosslinked aromatic isocyanate-based polyurethane resin becomes higher, and the pores can be more preferably temporarily stopped at high temperature. When a cross-linking agent is added to the prepolymer of the aromatic isocyanate-based polyurethane resin, the cross-linking agent is added so that the weight ratio of the prepolymer and the cross-linking agent is in the range of 100:0 to 50:50. It is preferable to add (millable gum mold processing method). That is, the preferable range of the weight ratio of the prepolymer and the crosslinking agent is in accordance with the preferable range of the weight ratio of the aromatic isocyanate polyurethane resin and the crosslinking agent.

In addition, a part of these polyfunctional isocyanate compounds may exist in the sealing agent in an unreacted state.

(2.2) Monomer Having Ethylenically Unsaturated Group For the crosslinking agent, for example, a monomer having an ethylenically unsaturated group can be used.

Examples of the monomer having an ethylenically unsaturated group include triallyl isocyanurate (TAIC), ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol trichloride. Examples include (meth)acrylate and dipentaerythritol hexa(meth)acrylate. Such a cross-linking agent having an ethylenically unsaturated group can be cross-linked by using together with a radical polymerization initiator such as an organic peroxide, or by irradiating with an electron beam. For example, a polyurethane resin is blended with a cross-linking agent having an ethylenically unsaturated group and melt-kneaded to obtain a resin composition, which is then crushed and irradiated with an electron beam to obtain the resin composition. Adjust the hardness of the object. At this time, the cross-linking agent having an ethylenically unsaturated group contained in the resin composition can also cross-link with the main chain of the polyurethane resin while polymerizing with each other.

The irradiation dose of the electron beam is, for example, preferably 5 kGy or more and 150 kGy or less, more preferably 10 kGy or more and 120 kGy or less, and further preferably 20 kGy or more and 100 kGy or less.

(2.3) Polyvalent amine and polyhydric alcohol For the cross-linking agent, for example, polyvalent amine or polyhydric alcohol can be used. The polyvalent amine or polyhydric alcohol crosslinks by reacting with the isocyanate group remaining at the polyurethane terminal during melt-kneading with the polyurethane resin. Further, in a polyurethane resin having a polyester skeleton or a polyether ester skeleton, a transesterification reaction is caused with an ester group existing in the main chain to form a crosslinked structure via a newly generated amide bond or ester bond. can do. In particular, in the polyurethane resin having no terminal isocyanate group, or in a very small amount, by using the polyfunctional amine or the polyhydric alcohol in combination with the above-mentioned polyfunctional isocyanate compound, the hardness of the polyurethane resin is preferably adjusted. can do. The polyvalent amine and the polyhydric alcohol are also cross-linking agents for cross-linking the isocyanate group-terminated prepolymer (cast molding method).
Examples of the polyvalent amine include 3,3′-dichlorobenzidine, 4,4′-methylenebis-2-chloroaniline, and trimethylenebis(4-aminobenzoate).

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, and 2, Alkylene glycol such as 2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polyoxyalkylene glycol such as polytetramethylene glycol, and bisphenols such as bisphenol A Etc. can be used. As the trihydric or higher alcohols, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like can be used in combination.

(2.4) Polyfunctional Epoxy Compound For the cross-linking agent, for example, a polyfunctional epoxy compound can be used. The polyfunctional epoxy compound crosslinks by reacting with the hydroxyl group remaining at the terminal of the polyurethane during melt kneading with the polyurethane resin. Further, in a polyurethane resin having a polyester skeleton or a polyether ester skeleton, a crosslinked structure can be formed by reacting with a carboxyl group existing at the terminal. In particular, in a polyurethane resin having no terminal hydroxyl group or carboxyl group, or in a polyurethane resin having only a small amount, a polyfunctional epoxy compound and the above-mentioned polyvalent amine or polyhydric alcohol are used in combination to produce a polyurethane resin The hardness can be adjusted appropriately.

Examples of polyfunctional epoxy compounds include tris(2,3-epoxypropyl)isocyanurate and poly(glycidyl methacrylate).

(2.5) Heat Treatment The hardness of the polyurethane resin can be adjusted by subjecting the polyurethane resin containing a crosslinking agent to a heat treatment to further promote crosslinking. To promote crosslinking by heat treatment, the polyurethane resin containing a crosslinking agent can be held at a predetermined temperature for a predetermined time. The heat treatment may be performed in air, in an inert gas such as nitrogen, or under reduced pressure, if necessary.

(3) Electron Beam Irradiation Further, the hardness of the resin composition may be adjusted by irradiating the melt-extruded resin composition with an electron beam to cut or crosslink the main chain of the polyurethane resin. In this case, the resin composition may or may not contain a crosslinking agent.

The irradiation dose of the electron beam is, for example, preferably 5 kGy or more and 150 kGy or less, more preferably 10 kGy or more and 120 kGy or less, and further preferably 20 kGy or more and 100 kGy or less. Here, if the value of the irradiation dose of the electron beam is too small, the hardness of the polyurethane resin is not sufficiently high, and if the value of the irradiation dose is too large, the main chain of the polyurethane resin is cut more than necessary. Hardness decreases. On the other hand, when the irradiation dose of the electron beam is within the above-mentioned preferable range, a sealing material that can temporarily stop the pores can be obtained.

[Other compounding agents in resin composition]
The eye-stopping agent according to the present embodiment can further contain various compounding agents that are usually added to the eye-stopping agent within a range that does not impair the purpose of the present embodiment. For example, various additives such as a decomposition accelerator, a filler, an antioxidant, and a decomposition inhibitor can be mentioned. These various additives can be used alone or in combination of two or more.

(Decomposition accelerator)
The resin composition may contain a decomposition accelerator. The decomposition accelerator accelerates decomposition of the resin composition contained in the sealing agent, and examples thereof include an acid and an acid precursor, and an acid precursor is more preferable.

More specifically, examples of the decomposition accelerator include lactones such as glycolide and lactide, acid anhydrides such as 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), diethyl oxalate and the like. And sulfonic acid esters such as ethyl p-toluenesulfonate, and phosphoric acid esters.

The content of the decomposition accelerator in the resin composition is, for example, preferably 0.1 wt% or more and 20 wt% or less, more preferably 0.3 wt% or more and 15 wt% or less, and 0.5 wt% or more 10 wt%. % Or less is more preferable. According to the above-mentioned preferable range, the content of the decomposition accelerator is not too small, so that the decomposition promotion effect is sufficient. Moreover, since the content is not too large, the initial hardness does not decrease, and a sufficient sealing retention time can be obtained.

(filler)
The resin composition may contain a filler in a blending amount that does not depart from the scope of the present invention. Examples of the filler include organic or inorganic fibrous reinforcing materials, granular or powdery reinforcing materials, and the like, and these can be used alone or in combination of two or more kinds.

Examples of the fibrous reinforcing material include inorganic fibers such as glass fiber, carbon fiber, asbestos fiber, silica fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber and potassium titanate fiber, stainless steel. Examples thereof include metal fibrous substances such as aluminum, titanium, copper and brass, and high melting point organic fibrous substances such as aramid fiber, kenaf fiber, polyamide, fluororesin, polyester resin and acrylic resin.

As the granular or powdery reinforcing material, mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder, zinc oxide, nickel carbonate, iron oxide, quartz powder, magnesium carbonate Examples thereof include barium sulfate and the like, but a decomposable reinforcing material that does not affect production defects is more preferable. The filler may be treated with a sizing material or a surface treatment agent, if necessary.

When the filler is added to the resin composition, the content of the filler in the resin composition is preferably 2% by weight or more and 30% by weight or less, preferably 3% by weight or more and 25% by weight or less. Is more preferable, and it is more preferable that the amount is 4 wt% or more and 20 wt% or less. In the above-mentioned preferable range, the content of the filler is not too small, so that the hardness of the polyurethane resin becomes sufficiently high. Further, since the content of the filler is not too large, even if the filler remains after the decomposition of the polyurethane resin, the filling can be sufficiently canceled.

<Well fluid>
The well fluid according to the present embodiment contains the above-mentioned sealing agent.

Well fluid is also commonly referred to as a finish fluid. The sealing agent according to the present embodiment has higher dispersibility in water and higher wettability than a starch derivative which is one of the dehydration reducing agents contained in the well fluid. The high dispersibility of the filling agent in the well fluid is effective for effectively filling the pores, and a tool for injecting the well fluid into the well (for example, a drill and its peripheral members, etc.) ) Also contributes to prevent clogging by the sealing agent. Therefore, the plugging agent according to the present embodiment can be preferably used as a plugging agent to be mixed with an aqueous well fluid.

Well fluid according to the present embodiment, the environment in the well hole using the well fluid, particularly, depending on the temperature or pressure of the high temperature environment, the type of resin composition contained in the filler, the physical properties , Composition (including additives, etc.), shape, size and the like can be appropriately selected and combined. Therefore, the sealing material according to the present embodiment may use different materials or a combination of materials.

The content of the above-mentioned sealing agent in the well fluid according to the present embodiment is not particularly limited and is usually 1% by weight or more and 15% by weight or less, and preferably 3% by weight or more and 10% by weight or less.

In addition to the above-mentioned filler, the well fluid according to the present embodiment may contain various compounding agents that are usually added to the well fluid, as long as the purpose of the present embodiment is not impaired. For example, an inorganic weighting agent such as barite (BaSO ₄ ) and calcium carbonate, a clay swelling inhibitor of an alkali metal halide or an alkaline earth metal halogen compound (salt) such as NaCl, KCl and CaCl ₂ , or a solid-free specific gravity Regulators, organic colloid agents such as guar gum and carboxymethyl cellulose (CMC), inorganic colloid agents (clays, etc.), dispersant demulcent agents, surfactants, pH adjusters, other mud-preventing agents, converters, defoamers. Agents, lubricants, preservatives, bactericides, anticorrosion agents and the like, and they can be contained at a concentration according to the environment in the wellbore where the well fluid is used.

<How to drill wells>
In the well drilling method according to the present embodiment, the above-mentioned filling agent is used to perform temporary filling.

For example, in the well drilling method according to the present embodiment, the above-mentioned filling agent is used for drilling a well in a reservoir section using a drill, for example, for drilling a shale layer that produces shale gas and oil. Can be used for Further, in the well drilling method according to the present embodiment, the filling fluid containing the filling agent according to the present embodiment, before the well fluid of another kind is introduced into the well hole, May be made to flow into.

Further, the environment in which the sealing agent according to the present embodiment is used, in particular, depending on the temperature or pressure of a high-temperature environment, the type, physical properties, composition, shape, and size of the resin composition contained in the sealing agent are determined. It can be appropriately selected and combined.

Examples will be shown below to describe the embodiments of the present invention in more detail. Of course, the present invention is not limited to the following examples, and it goes without saying that various aspects are possible in details. Further, the present invention is not limited to the above-described embodiments, various modifications can be made within the scope of the claims, and the present invention is also applicable to embodiments obtained by appropriately combining the disclosed technical means. It is included in the technical scope of the invention. Moreover, all the documents described in this specification are incorporated by reference.

With respect to each of Examples 1 to 7 and Comparative Example, a sealing agent was prepared under the following conditions.

<Example 1>
[Manufacture of evaluation sealing agent]
(Production of hardness evaluation sample and sealing evaluation sample)
First, as the HDI-based polyurethane resin, 1800 g of Pandex (registered trademark) T-R3080 manufactured by DIC Covestro Polymer Co., Ltd. having a durometer type D hardness of 28 at 23° C. was weighed and put into a polyethylene bag. In addition, 200 g of HDI as a cross-linking agent was weighed and put into the polyethylene bag. That is, the crosslinking agent was added so that the content of the crosslinking agent in the HDI-based polyurethane resin after addition was 10% by weight. After the addition of the cross-linking agent, a polyethylene bag was hand shaken to stir the HDI-based polyurethane resin and the cross-linking agent in the polyethylene bag for 3 minutes to obtain a mixture (blend). After obtaining the blend, the blend was mixed for 5 minutes at a temperature of 230° C. and melt extruded from a die using the following kneading extruder.
・Kneading extruder: 2D30W2 (manufactured by Toyo Seiki Seisakusho Co., Ltd.)
・Screw size: Diameter 30mmφ, L/D=30
・Screw rotation speed: 50 rpm
・Pelletizer: Model SCF-150 (made by Isuzu Kakoki Co., Ltd.)
The blend obtained by melt extrusion was made into a strand, and then pelletized through a pelletizer.

In addition to the pellet, a hardness evaluation sample was also manufactured. Specifically, the process from the die to the melt extrusion was carried out in the same manner as the sample for sealing evaluation, and after the melt extrusion, it was hot press molded into a sheet having a thickness of 3 mm. Then, it heat-processed at 120 degreeC for 2 hours in nitrogen atmosphere, and obtained the sample for hardness evaluation.

(Electron beam irradiation)
The pellets obtained by melt extrusion and a 3 mm-thick sheet-like sample for hardness evaluation were irradiated with an electron beam at 60 kGy.

(Durometer type D hardness measurement)
Durometer type D hardness of the hardness evaluation sample was measured using a hardness meter according to ISO7619/JIS K 6253, by stacking two 3 mm-thick sheet-like hardness evaluation samples to a thickness of 6 mm. A durometer type D GS-720R manufactured by Teclock Co., Ltd. was used as the hardness tester.

As the evaluation sample used for measuring the durometer type D hardness, one having a sufficiently stable durometer type D hardness was used. Specifically, the durometer type D hardness after heat treatment of the evaluation sample in a nitrogen atmosphere at 120° C. for 2 hours does not change by 10% or more as compared with the durometer type D hardness before heat treatment. I was there.

When the durometer type D hardness changes by 10% or more before and after the heat treatment, the heat treatment and the measurement are repeated, and the durometer D hardness when the change in the durometer D hardness before and after the heat treatment is less than 10% is the durometer D of the evaluation sample. Hardness was used.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample after electron beam irradiation was 39.

(Production of eye-stopper by crushing sample)
The pellets after electron beam irradiation were pulverized by the freeze pulverization method by immersion in liquid nitrogen using the pulverizer shown below. In this way, a powder-shaped sealing agent for evaluation was prepared. Specifically, the pellet was cooled by immersing it in liquid nitrogen for 5 minutes, and the cooled sample was put into a pulverizer at 125 g/min to be pulverized. Liquid nitrogen was also added at the same time when the sample was put into the crusher. As a result, the evaluation sealing agent of Example 1 was obtained.
・Grinding machine: Xseed mill EM-1A type (Makino Sangyo Co., Ltd.)
・Turntable:
Pin disk diameter: 160mm
Pin diameter: 3.5 mm
Pin length: 19mm
Body side pin number: 178 body side pin array: 3 rows Body side pin interval: 3.5mm
Door side pin number: 168 Door side pin array: 3 rows Door side pin interval: 2.5 mm
・Crushing speed: Main body side pin disk: 8000 rpm (133 Hz)
・Door side pin disk: 12000 rpm (200 Hz)
(Measurement of median diameter (50% D) of the evaluation sealing agent)
The median diameter (50% D) of the obtained powdery sealing agent for evaluation was measured using SALD3000 manufactured by Shimadzu Corporation, which is a laser diffraction particle size distribution measuring device. As shown in Table 2, the median diameter (50% D) of the powdery sealing agent for evaluation was 676 μm.

[Production of evaluation fluid (hereinafter also referred to as evaluation muddy water)]
Based on the composition ratios shown in Table 1 below, the obtained sealing agent for evaluation was blended to prepare muddy water for evaluation.

The sodium chloride in the 10 wt% sodium chloride aqueous solution in Table 1 is manufactured by Junsei Chemical Co., Ltd. The AMPS polymer is Driscal (registered trademark)-D manufactured by Ternite Co., Ltd. Lignin is available from Halliburton Energy Services, Inc. DURENEX (registered trademark) PLUS manufactured by Mitsubishi. The oxygen scavenger is Ternite (registered trademark) OS-5 manufactured by Ternite Co., Ltd.

[Evaluation of eyesight]
The evaluation of sealing was performed by a sealing test using a plug tester (Fliter Press HPHT 500ML manufactured by Fann Instrument Company) including the filter disk shown in FIG. In the filling test, a Ceramic Filter Disc 50 (Part NO. 210540) manufactured by Fann Instrument Company was used as a ceramic filter having a pore size of 50 μm.

The filling test will be described below with reference to FIG. FIG. 1 is a diagram schematically showing a plug tester used for a filling test with evaluation muddy water.

As shown in FIG. 1, after putting the muddy water for evaluation in the plug tester, a pressure of 100 psi from above and a pressure of 100 psi from below were applied to the plug tester. As a result, the difference between the pressure from the top and the pressure from the bottom was 0 psi, and the filter disk was kept free from pressure before the temperature was raised.

The upper container containing the muddy water for evaluation was heated to 120° C. and held. After raising the temperature, the plug tester was subjected to a pressure of 600 psi from above. As a result, the difference between the pressure from the top and the pressure from the bottom is 500 psi, and the pressure of 500 psi from the top is applied to the filter disk as the difference.

Next, the lowering valve of the lower container was opened, and the filling test was started while maintaining the temperature and pressure.

Here, as described above, the filter has pores of 50 μm, and water is allowed to permeate from the upper container to the lower container through the pores. Therefore, the amount of water permeated from the filter was measured every predetermined time. The amount of permeation was measured by collecting water permeated through the lower valve of the lower container.

The water permeation recovery point (the point where the temporary sealing was canceled) was set when the amount of permeation of water per predetermined time increased, and the sealing test was completed.

The time from the start of the filling test to the point of reaching the water permeation recovery point is defined as the filling maintenance time, and when the filling maintenance time is 1 hour or more and 960 hours (40 days) or less, the filling evaluation is “ "○" was given, and in other cases, the blinding evaluation was given as "x".

As shown in Table 2, the sealing retention time at 120° C. was 7 hours.

<Example 2>
In Example 2, a hardness evaluation sample and an evaluation sealing agent were produced in the same manner as in Example 1 except that MDI was used instead of HDI as the crosslinking agent.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 34.

As shown in Table 2, the evaluation sealing agent of Example 2 had a median diameter (50% D) of 396 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in Example 1, and the sealing test was conducted in the same manner as in Example 1. As shown in Table 2, the sealing retention time at 120° C. was 3 hours.

<Example 3>
In Example 3, an MDI polyurethane resin was used in place of the HDI polyurethane resin, a crosslinking agent was not added, and no electron beam irradiation was performed. A stop evaluation sample was produced.

Here, in this example, Pandex (registered trademark) T-5070 manufactured by DIC Cobestropolymer Co., Ltd. having a durometer type D hardness of 60 at 23° C. was used as the MDI polyurethane resin.

As shown in Table 2, the durometer type D hardness of the durometer type D hardness at 23° C. of the hardness evaluation sample was 60.

A sealing agent for evaluation was prepared in the same manner as in the above-mentioned examples. As shown in Table 2, the median diameter (50% D) of the evaluation sealing agent was 334 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and a sealing test was performed at 120° C., 140° C. and 149° C. by the same method as in the above-mentioned examples. It was As shown in Table 2, the sealing retention time at 120°C was more than 2328 hours. The retention time at 140° C. was 65 hours. The retention time at 149° C. was 28 hours.

<Example 4>
A hardness evaluation sample and a sealing evaluation sample were produced in the same manner as in Example 3 except that 10% by weight of MDI was added as a crosslinking agent to the MDI polyurethane resin. The method of addition to the MDI-based polyurethane resin is the same as in Examples 1 and 2.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 64.

A sealing agent for evaluation was prepared in the same manner as in the above-mentioned examples. As shown in Table 2, the median diameter (50% D) of the sealing agent for evaluation was 402 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and the sealing was performed at 120°C, 130°C, 140°C and 149°C in the same manner as in the above-mentioned examples. The test was conducted. As shown in Table 2, the sealing retention time at 120° C. was longer than 1464 hours. The retention time at 130° C. was longer than 1224 hours. The retention time at 140° C. was 70 hours. The retention time at 149° C. was 31 hours.

<Example 5>
As the base resin composition, a hardness evaluation sample and an evaluation sealing agent were produced in the same manner as in Example 3 except that the MDI polyurethane resin was further added in addition to the HDI polyurethane resin.

More specifically, 1100 g of the above HDI-based polyurethane resin was weighed and 900 g of MDI-based polyurethane resin was weighed and put into a polyethylene bag. After charging, a handshake was carried out in the same manner as in the above-mentioned example, and the HDI-based polyurethane resin and the MDI-based polyurethane resin were stirred to obtain a blended product. In this way, the HDI-based polyurethane resin and the MDI-based polyurethane resin were mixed at a weight ratio of 55:45.

Then, similarly to the above-mentioned example, the blended product was melt-extruded (melt-kneaded) to manufacture a hardness evaluation sample and an evaluation sealing agent.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 34.

As shown in Table 2, the evaluation sealant produced in the same manner as in the above-mentioned example had a median diameter (50% D) of 345 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and a sealing test was performed at 120° C. by the same method as in the above-mentioned examples. As shown in Table 2, the sealing retention time at 120° C. was 62 hours.

<Example 6>
A hardness evaluation sample and an evaluation sealing agent were produced in the same manner as in Example 5 except that the HDI polyurethane resin and the MDI polyurethane resin were mixed at a weight ratio of 65:35.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 30.

As shown in Table 2, the sealing medium for evaluation produced in the same manner as in the above-mentioned example had a median diameter (50% D) of 358 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and a sealing test was performed at 120° C. by the same method as in the above-mentioned examples. As shown in Table 2, the sealing retention time at 120° C. was 1 hour.

<Example 7>
A hardness evaluation sample and an evaluation sealing agent were produced in the same manner as in Example 5 except that the HDI polyurethane resin and the MDI polyurethane resin were mixed at a weight ratio of 70:30.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 30.

As shown in Table 2, the evaluation sealing agent produced in the same manner as in the above-mentioned example had a median diameter (50% D) of 438 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and a sealing test was performed at 120° C. by the same method as in the above-mentioned examples. As shown in Table 2, the sealing retention time at 120° C. was 2 hours.

<Comparative example>
A hardness evaluation sample and an evaluation sealing agent were produced in the same manner as in Example 1 except that the crosslinking agent was not added to the HDI polyurethane resin and the electron beam was not irradiated.

As shown in Table 2, the durometer type D hardness at 23° C. of the hardness evaluation sample was 28.

As shown in Table 2, the evaluation sealing agent produced in the same manner as in the above example had a median diameter (50% D) of 337 μm.

Next, muddy water for evaluation was prepared from the obtained sealing agent for evaluation in the same manner as in the above-mentioned examples, and a sealing test was conducted at 120° C. in the same manner as in the above-mentioned examples. As shown in Table 2, the sealing retention time at 120° C. was 0 hour.

As is clear from Table 2, as a result of performing a sealing test using the sealing agents of Examples 1, 2 and 5 to 7, at 120°C, the sealing retention time was 1 hour or more and 960 hours or less. From this, the durometer type D hardness of Examples 1, 2 and 5 to 7 is 29 or more, and the sealing agent containing at least one of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin is It was found that at a high temperature of 120° C., the pores can be suitably stopped temporarily.

Moreover, as a result of performing a sealing test using the sealing agents having durometer type D hardness of 29 or more in Examples 3 and 4, at 140° C. and 149° C., the sealing retention time is 1 hour or more and 960° C. hours or less. was. From this, the durometer type D hardness of Examples 3 and 4 is 29 or more, and the sealing agent containing the aromatic isocyanate polyurethane resin is suitable for temporarily sealing the pores at a high temperature of 140° C. and 149° C. I knew I could do it.

On the other hand, the durometer type D hardness of the comparative example is 28, and as a result of a sealing test using a sealing agent containing an aliphatic isocyanate polyurethane resin, the sealing retention time is 0 hour at 120° C., It did not have a blinding function.

From the above, a durometer type D hardness of 29 or more, and a sealing agent containing at least one of an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin, is suitable for temporary pores at high temperatures. I found that I could stop it.

INDUSTRIAL APPLICABILITY The present invention can be used as a filling agent for temporarily filling pores in a high temperature environment such as a well with a deep depth, a well fluid, and the like.

Claims (11)

A filling agent that stops the pit wall,
The sealing agent is a powder of a resin composition containing a polyurethane resin,
The polyurethane resin is at least one of an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin,
A sheet-shaped molded product molded from the resin composition has a durometer type D hardness at 23° C. of 29 or more, which is a sealing agent. The aliphatic isocyanate forming the aliphatic isocyanate-based polyurethane resin is at least one aliphatic isocyanate selected from the group consisting of hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexylmethane diisocyanate. The filling agent according to claim 1, which is The aromatic isocyanate constituting the aromatic isocyanate-based polyurethane resin is at least one aromatic isocyanate selected from the group consisting of diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate. The sealing agent according to claim 1 or 2. At least 1 of the said aliphatic isocyanate type polyurethane resin and the said aromatic isocyanate type polyurethane resin contains the polyester skeleton at least, The sealing of any one of Claims 1-3 characterized by the above-mentioned. Agent. The resin composition according to claim 1, further comprising a crosslinking agent. The polyurethane resin is composed of the aliphatic isocyanate polyurethane resin, and the weight ratio of the aliphatic isocyanate polyurethane resin to the cross-linking agent is in the range of 99.8:0.2 to 50:50. The sealing agent according to claim 5, which is characterized in that The polyurethane resin comprises the aromatic isocyanate-based polyurethane resin, and the weight ratio of the aromatic isocyanate-based polyurethane resin to the cross-linking agent is in the range of 100:0 to 50:50. Item 5. A sealing agent according to item 5. The cross-linking agent is at least one cross-linking agent selected from the group consisting of polyfunctional isocyanate compounds, monomers having an ethylenically unsaturated group, polyvalent amines, polyhydric alcohols, and polyfunctional epoxy compounds. The sealing agent according to any one of claims 5 to 7. The aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin are contained, and the weight ratio of the aliphatic isocyanate-based polyurethane resin and the aromatic isocyanate-based polyurethane resin is in the range of 80:20 to 0:100. It exists, The sealing agent of any one of Claims 1-5 characterized by the above-mentioned. A well fluid comprising the plugging agent according to any one of claims 1 to 9. A well drilling method, which comprises performing temporary filling using the filling material according to any one of claims 1 to 9.

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