WO2018168530A1

WO2018168530A1 - Lost circulation material and use therefor

Info

Publication number: WO2018168530A1
Application number: PCT/JP2018/008065
Authority: WO
Inventors: 卓磨小林; 瑞輝斎藤; 浩幸佐藤; 健夫 ▲高▼橋
Original assignee: 株式会社クレハ; 独立行政法人石油天然ガス・金属鉱物資源機構
Priority date: 2017-03-16
Filing date: 2018-03-02
Publication date: 2018-09-20
Also published as: JP2020097636A

Abstract

Provided is a lost circulation material capable of temporarily sealing wide fractures even in a high temperature environment. Specifically provided is a lost circulation material for sealing the walls of a well, wherein the lost circulation material contains pellets and a powder that are each formed from a resin composition comprising a polyurethane resin, and the pellets have an indentation hardness of at least 37 at 23°C.

Description

Sealants and their use

The present invention relates to a sealant for temporarily closing a pit wall and use thereof.

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 into rock layers rich in oil and gas. Produced through wells.

For excavation and finishing work of the well, the debris generated from the periphery of the drill during the well excavation is transported to the ground surface, the underground pressure is adjusted to maintain the stability of the well, and the collapse of the formation is suppressed. Circulating fluid (muddy water or finishing fluid) is used to cool the air.

Here, if the reservoir that is the production layer is a highly permeable formation, or if natural fractures (cracks) exist in the shale layer, fluid will be lost through the high permeable formation and cracks in the well wall, and circulating mud The volume may decrease or the muddy water column pressure may decrease.

As a result, there is a risk of not only destabilizing the borehole, lowering the efficiency of excavation and processing work, and causing the production failure of the reservoir due to the fluid remaining in the reservoir, but also a highly functional and expensive fluid Excavation costs may increase due to spillage. Therefore, in order to suppress the outflow of the fluid as much as possible, a method of temporarily closing the pit wall using a decomposable sealant is used.

As the sealant, calcium carbonate or the like is generally used. However, when shifting to production, it is necessary to decompose calcium carbonate as the sealant by acid treatment. The work time for performing this acid treatment is required, and if the acid treatment is insufficient, the amount of recovered resources may be reduced due to insoluble residues such as calcium carbonate residue as a filler.

Therefore, in order to reduce the acid treatment cost while shortening the work time required for the acid treatment, and to prevent the reduction of the resource recovery amount due to the remaining of the filler, the decomposition function is decomposed after a predetermined period of time. An eye-catching agent using a degradable material that has disappeared has attracted attention.

Patent Document 1 describes a particulate filler including a degradable material for temporarily closing a well.

Patent Document 2 describes a sealing agent containing a synthetic resin 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.).

US Patent Application Publication No. 2008/0200352 International Publication WO2015 / 072317

With the decrease in oil and gas yield in individual wells and the increase in energy consumption that increases year by year as production progresses, oil development moves from easy to more severe conditions, and polar conditions with severe weather conditions. There is also a need for deep drilling in the deep water well development area of the ocean. In particular, as the depth of the well is increased, the conditions for laying the well become stricter. For example, at a high depth exceeding about 3000 m in the ground, a high temperature environment of about 110 ° C. or more is obtained depending on the location. Therefore, a sealant that can be temporarily stopped even under such a high temperature environment is demanded.

Fractures have various widths, and in particular, a sealant capable of temporarily spotting large fractures having a crack width of, for example, about 3 mm or more in the opening or inside of the fracture. Is required.

However, Patent Document 1 and Patent Document 2 do not describe at all that the filler can temporarily stop such a large fracture.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a sealant or the like that can suitably temporarily seal a large fracture even in a high temperature environment.

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

The sealant according to the present invention is a sealant for sealing a well wall, and the sealant includes pellets and powder formed from a resin composition containing a polyurethane resin, The indentation hardness at 23 ° C. is 37 or more.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sealant that can temporarily seal a large fracture even in a high temperature environment.

It is a figure which shows roughly 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.

<Closing agent>
In the present embodiment, time-degradable-lost circulation materials are typically used for temporarily closing a well wall in various steps of well drilling (well laying). For purposes, this refers to the material blended into the well fluid.

The sealant according to the present embodiment is a pellet and powder (powder) formed from a resin composition containing a polyurethane resin. Here, the pellet has an indentation hardness at 37 ° C. of 37 or more. Further, the resin composition forming the pellets and the resin composition forming the powder may be the same resin composition or different resin compositions.

Thereby, the sealant according to the present embodiment is such that the seal part where the fracture is blocked by the sealant cannot withstand the pressure applied to the seal, deforms or collapses, and the seal is released. Can be set in the range of 1 hour to 960 hours (40 days), for example, at 110 ° C. or higher and 200 ° C. or lower. Thereby, it is possible to release the seal before various operations are completed while securing various work times to be performed inside and outside the well during the seal.

In addition, according to the sealant according to the present embodiment, for example, a large fracture with a width of about 3 mm can be temporarily stopped even in a high temperature environment of 110 ° C. or more and 200 ° C. or less.

The weight ratio of the pellets to the powder in the filler is preferably 5:95 to 60:40, more preferably 10:90 to 55:45, and 15:85 to 50:50. More preferably. When the weight ratio between the pellet and the powder is within this preferable range, a large fracture can be temporarily stopped without a gap.

〔pellet〕
The pellet is a pellet formed of a resin composition containing a polyurethane resin, and the indentation hardness at 23 ° C. is 37 or more. The indentation hardness at 23 ° C. is preferably 37 or more and 98 or less, and more preferably 37 or more and 85 or less. When the indentation hardness of the pellet at 23 ° C. is 37 or more, the filler is neither too soft nor too hard, so that a large fracture can be temporarily spotted at a high temperature.

In the present application, the indentation hardness of the pellet is measured using a durometer type D hardness meter of ISO7619 / JIS K 6253. More specifically, a resin composition containing a polyurethane resin is formed into a strand having a diameter of 2.5 mmφ, and the indentation hardness of the strand is measured at 23 ° C. More precisely, in the measurement of indentation hardness, the strand is cut into a length of 3 mm. That is, the indentation hardness defined in the present application is a hardness value of a pellet having a diameter of 2.5 mmφ and a length of 3 mm measured by applying a load of 5 kgf with a durometer type D hardness meter.

The dimensions of the pellets used for indentation hardness measurement are those having a longest width of 0.5 mm to 10 mm and a shortest width of 0.5 mm to 10 mm in the projected cross section. The shape of the pellet is typically a cylinder, and may have a cone, ellipsoid, sphere, cuboid, cube, star shape, polyhedron, or a part of them.

The pellet is prepared by, for example, melt-kneading an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin, which are polyurethane resins, and appropriately molding or pulverizing the obtained resin composition by a known molding method. Can do. In addition, when mix | blending a crosslinking agent with a resin composition, it is good to melt-knead the polyurethane resin which mix | blended the crosslinking agent.

The heating temperature and time during the melt-kneading may be appropriately adjusted in consideration of the melting point of the aliphatic isocyanate-based polyurethane resin and aromatic isocyanate-based polyurethane resin and the reaction temperature of the crosslinking agent. The pellets contained in the filler are obtained by appropriately pelletizing the resin composition obtained by melt kneading by a known method. In addition, the pellets may be heat-treated at a predetermined temperature for a predetermined time before the test, if necessary, in order to remove mechanical strain during molding and stabilize the indentation hardness.

〔powder〕
The powder is a powder contained in the filler and is formed from a resin composition. Here, the resin composition may be the same resin composition as the resin composition forming the pellet. As an example, the powder may be obtained by pulverizing pellets into powder by freeze pulverization. Thereby, a powder having a small median diameter of particles formed from the resin composition can be obtained.

The powder preferably has a median diameter (50% D) of 80 μm or more and 800 μm or less, and the larger the median diameter of the powder, the larger the median diameter of the powder at the opening or inside of the fracture. preferable. Thus, by mixing with pellets, it is possible to obtain a sealing agent that can be temporarily stopped without gaps in the sealing portion even when the width of the fracture of a large fracture is about 1 mm to 3 mm. it can.

The shape of the particles of the powder is not limited, but may be spherical, scaly, ellipsoidal, prismatic, rod-like, star-shaped, polygonal, and fibrous (short fibers). Further, it may be porous with small pores. Moreover, the combination of what differs in a shape and the thing from which a particle size differs may be sufficient.

(Resin composition)
The resin composition is a main material of pellets and powder contained in the filler, and includes a polyurethane resin.

Polyurethane resin generally refers to a polymer compound derived from an isocyanate compound regardless of the presence or absence of a urethane bond. Specifically, it is a polymer compound composed of a chemical bond such as a urethane bond, and in some cases a urea bond or an amide bond. Examples of the polyurethane resin include a thermoplastic polyurethane resin and a 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 the meaning of “aromatic isocyanate-based polyurethane resin”.

The thermoplastic polyurethane resin is a polyurethane resin that can be repeatedly melted by heating, and is a polyurethane resin having a branched structure among aliphatic isocyanate-based polyurethane resins and aromatic isocyanate-based polyurethane resins. Although it may be, it is more preferably a polyurethane resin having a linear structure.

The thermosetting polyurethane resin is a polyurethane resin obtained by curing a molten prepolymer by heating. More specifically, it is a polyurethane resin that can be obtained by crosslinking a thermoplastic polyurethane resin or a polyurethane resin prepolymer with a crosslinking agent. Examples of the thermosetting polyurethane resin include those obtained by molding methods such as the following (i) to (iii).
(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 aliphatic isocyanate or aromatic isocyanate is generated, and a crosslinking agent is kneaded by roll kneading, It is obtained by heating in a mold and allowing the crosslinking to proceed.
(Ii) Cast mold forming method For example, an isocyanate group-terminated prepolymer having a skeleton such as polyester polyol and a structure derived from aliphatic isocyanate or aromatic isocyanate is generated, and a crosslinking agent is added thereto. It is obtained by pouring a liquid mixture into a mold and connecting the ends by chain extension or crosslinking.
(Iii) Thermoplastic Molding Process For example, a thermoplastic polyurethane resin pellet is melted by heating and obtained through extrusion molding or injection molding. In addition, a partially crosslinked polyurethane resin can be obtained by adding a cross-linking agent as necessary at the time of melting. Moreover, crosslinking can be advanced by heat-treating a thermoplastic polyurethane resin to which a crosslinking agent has been added at a predetermined temperature for a predetermined time as required, and the hardness can be adjusted.

[Adjustment of hardness]
Here, the indentation hardness of the pellet formed from the resin composition is (1) combined use of a plurality of polyurethane resins, (2) crosslinking of the polyurethane resin with a crosslinking agent, and heat treatment of the polyurethane resin to which the crosslinking agent is added (3) It is adjusted by crosslinking of the polyurethane resin by electron beam irradiation and (4) blending of the filler.

(1) Combination use of a plurality of polyurethane resins In one embodiment, the indentation hardness of the pellets can be adjusted by using a plurality of polyurethane resins having different hardnesses.

The polyurethane resin for adjusting the hardness of the resin composition includes an aliphatic isocyanate polyurethane resin and an aromatic isocyanate polyurethane resin. Here, the aliphatic isocyanate-based polyurethane resin generally has a low hardness and a high decomposition rate. In addition, the aromatic isocyanate-based polyurethane resin has a higher hardness and a slower decomposition rate than the aliphatic isocyanate-based polyurethane resin.

The weight ratio of the aliphatic isocyanate-based polyurethane resin to the aromatic isocyanate-based polyurethane resin is preferably in the range of 80:20 to 0: 100, more preferably in the range of 70:30 to 0: 100. 60:40 to 0: 100 is more preferable. Thereby, it can adjust suitably so that the indentation hardness of a resin composition may exist in a predetermined range. Therefore, a sealant capable of temporarily closing the well wall in a high temperature environment of 110 ° C. to 200 ° C. can be suitably produced.

Here, when the sealant contains an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin, the seal retention time is equal to the retention time of the aliphatic isocyanate-based polyurethane resin having a low hardness and the hardness. It is a time between the high-value aromatic isocyanate-based polyurethane resin and the sealing maintenance time. Note that the eye-keeping time here refers to the time when the eye-catching portion where the large fracture is eye-catching with the eye-stopping agent cannot withstand the pressure applied to the eye-opening, and is deformed or collapsed until the eye-opening is released. It means the time. The reason why it cannot withstand the pressure is, for example, that the strength over time of the resin composition contained in the filler is lowered.

Therefore, in the sealant, it is possible to adjust the seal keeping time by changing the mixing ratio of the aliphatic isocyanate polyurethane resin and the aromatic isocyanate polyurethane resin. That is, it is possible to adjust the eye keeping time suitable for the situation when drilling a well.

For example, when a thermosetting polyurethane resin is employed as the resin composition, the weight ratio of the prepolymer including a structure derived from aliphatic isocyanate to the prepolymer including a structure derived from aromatic isocyanate is 80: The indentation hardness of the resin composition may be adjusted by mixing so as to be in the range of 20 to 0: 100 and allowing the crosslinking to proceed with a crosslinking agent described later (millable gum mold forming method or cast mold forming 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 this specification, “aliphatic isocyanate-based polyurethane resin” is defined by the fact that the isocyanate for producing the polyurethane resin is “aliphatic isocyanate”. That is, the “aliphatic isocyanate-based polyurethane resin” is not defined by whether or not a skeleton such as a polyester skeleton constituting the main chain of the polyurethane resin has an “aliphatic” hydrocarbon skeleton.

The aliphatic isocyanate-based polyurethane resin is a polyurethane resin produced 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. In addition, aliphatic diisocyanate and an isocyanurate compound (trimer) of these aliphatic diisocyanates may be used in combination with the aliphatic isocyanate-based polyurethane resin. Among these, the aliphatic isocyanate is more preferably hexamethylene diisocyanate (HDI). In addition, in this specification, the aliphatic isocyanate type polyurethane resin produced | generated using hexamethylene diisocyanate (HDI) may be called a hexamethylene diisocyanate type polyurethane resin (HDI type polyurethane resin).

Examples of the skeleton constituting 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 these, from the viewpoint that desired hardness and hydrolyzability can be obtained, 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. Is preferred. In particular, a polyol containing a polyester skeleton or a polyether ester skeleton is called a polyester polyol. For example, an aromatic isocyanate-based polyurethane resin suitable as a sealant can be obtained by reacting a polyester polyol with an aromatic isocyanate.

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.

The polyether ester skeleton can 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 constituent unit include polyacetal, polyethylene glycol, and polytetramethylene glycol, and examples of the polyester constituent unit include the above-described polyester skeleton.

The weight average molecular weight of the aliphatic isocyanate polyurethane resin is preferably 10,000 or more and 250,000 or less, more preferably 50,000 or more and 200,000 or less, 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 filler having an appropriate hydrolyzability can be obtained.

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

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

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

Also, the isocyanate-terminated, hydroxyl-terminated or carboxyl-terminated prepolymer that can form these aliphatic isocyanate-based polyurethane resins can be suitably used to obtain a thermosetting polyurethane resin.

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

The aromatic isocyanate-based polyurethane resin is a polyurethane resin produced using an aromatic isocyanate, and typically an aromatic diisocyanate is exemplified as the aromatic isocyanate. Here, examples of the aromatic diisocyanate include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), and naphthalene diisocyanate (NDI). Moreover, aromatic diisocyanate and the isocyanurate compound (trimer) of these aromatic diisocyanates may be used together in the aromatic isocyanate polyurethane resin. Of these, the aromatic isocyanate is more preferably diphenylmethane diisocyanate (MDI). In the present specification, an aromatic isocyanate polyurethane resin produced using diphenylmethane diisocyanate (MDI) may be referred to as diphenylmethane diisocyanate polyurethane resin (MDI polyurethane resin).

The skeleton constituting the main chain of the aromatic isocyanate polyurethane resin is, for example, the same as the skeleton constituting the main chain of the aliphatic isocyanate polyurethane resin, the polyether skeleton, the polyester skeleton, the polyester polyol skeleton, the polyether ester skeleton, and Examples thereof include a poly (meth) acrylate skeleton, and these skeletons may coexist as a main chain of the aromatic isocyanate polyurethane resin. Among these, from the viewpoint that desired hardness and hydrolyzability can be obtained, the skeleton constituting the main chain of the aromatic isocyanate-based polyurethane resin is either or both of a polyester skeleton and a polyether ester skeleton. 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, an aromatic isocyanate suitable as a sealant by reacting a polyester polyol and an aromatic isocyanate. A polyurethane resin is obtained.

The polyester polyol 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 constituent unit include polyacetal, polyethylene glycol, and polytetramethylene glycol, and examples of the polyester constituent unit include the above-described polyester skeleton.

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, 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 filler having an appropriate hydrolyzability can be obtained.

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

Here, in the chemical formula (II), m ² is an integer of 1 to 10, and n ² is an integer of 5 to 40.

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

In addition, an isocyanate-terminated, hydroxyl-terminated or carboxyl-terminated prepolymer capable of forming these aromatic isocyanate-based polyurethane resins can be suitably used to obtain a thermosetting polyurethane resin.

(2) Crosslinking with a crosslinking agent In one embodiment, the filler suppresses the indentation hardness at 23 ° C. of pellets formed from the resin composition by blending the resin composition with a crosslinking agent.

The crosslinking agent is preferably at least one crosslinking agent 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. Moreover, a network-like crosslinked structure can be formed in a polyurethane resin by a combination of these. For this reason, the hardness of a resin composition can be prepared suitably.

In addition, as above-mentioned, a crosslinking agent may be added to an aliphatic isocyanate type polyurethane resin and an aromatic isocyanate type polyurethane resin (thermoplastic molding method), and in addition to the prepolymer for forming these polyurethane resins. Also good (millable gum mold processing and cast mold processing).

(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 group having active hydrogen present at the terminal or main chain of the polyurethane resin when one or both of an aliphatic isocyanate polyurethane resin and an aromatic isocyanate polyurethane resin is melt-kneaded. Crosslink to the base (thermoplastic molding process).

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

This crosslinks the main chain of one polyurethane resin and the main chain of another polyurethane resin via the polyfunctional isocyanate compound. When the polyurethane resin has a urea bond, the polyfunctional isocyanate can form the urea bond and the burette bond. The polyfunctional isocyanate compound also crosslinks the main chain of one polyurethane resin and the main chain of another polyurethane resin via the polyfunctional isocyanate compound by such a burette bond.

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

When the crosslinking agent is added to the aromatic isocyanate polyurethane resin, the weight ratio of the aromatic isocyanate polyurethane resin before addition to the crosslinking agent is in the range of 100: 0 to 50:50. It is preferable to add a crosslinking agent. It is preferable to add so that the weight ratio of the aromatic isocyanate polyurethane resin and the crosslinking agent is in the range of 99.7: 0.3 to 60:40, and 99.6: 0.4 to 70:30. It is more preferable to add so that it may become this range. By adding a cross-linking agent within the above-mentioned range, the hardness of the cross-linked aromatic isocyanate-based polyurethane resin becomes higher, and the pores can be more appropriately temporarily spotted at a high temperature. When a crosslinking agent is added to the prepolymer of the aromatic isocyanate polyurethane resin, the crosslinking agent is added so that the weight ratio of the prepolymer to the crosslinking agent is in the range of 100: 0 to 50:50. It is preferable to add (millable gum mold forming method). That is, the preferable range of the weight ratio between the prepolymer and the crosslinking agent conforms to the preferable range of the weight ratio between the aromatic isocyanate polyurethane resin and the crosslinking agent.

In addition, some of these polyfunctional isocyanate compounds may be present in the filler in an unreacted state.

(2.2) Monomer having an ethylenically unsaturated group For the cross-linking agent, for example, a monomer having an ethylenically unsaturated group can be used.

Examples of monomers having an ethylenically unsaturated group include triallyl isocyanurate (TAIC), ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and dipentaerythritol tris. (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. are mentioned. Such a cross-linking agent having an ethylenically unsaturated group can be cross-linked by, for example, using in combination with a radical polymerization initiator such as an organic peroxide or by irradiating an electron beam. For example, after blending a polyurethane resin with a crosslinking agent having an ethylenically unsaturated group and melt-kneading to obtain a resin composition, the resin composition is pulverized and irradiated with an electron beam. Adjust the hardness of the object. At this time, the crosslinking agent having an ethylenically unsaturated group contained in the resin composition can also be crosslinked with the main chain of the polyurethane resin while polymerizing each other.

The electron beam irradiation dose 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) Polyhydric amine and polyhydric alcohol As the crosslinking agent, for example, polyhydric amine or polyhydric alcohol can be used. The polyvalent amine or polyhydric alcohol crosslinks by reacting with the isocyanate group remaining at the end of the polyurethane during melt-kneading with the polyurethane resin. In addition, in polyurethane resins having a polyester skeleton or a polyether ester skeleton, a cross-linked structure is formed via a newly formed amide bond or ester bond by causing an ester exchange reaction with an ester group present in the main chain. can do. In particular, in a polyurethane resin in which a terminal isocyanate group does not exist or is present only in a trace amount, the hardness of the polyurethane resin composition is suitable by using a polyvalent amine or a polyhydric alcohol in combination with the polyfunctional isocyanate compound described above. Can be prepared. The polyvalent amine and the polyhydric alcohol are also crosslinking agents that crosslink the isocyanate group-terminated prepolymer (cast mold forming 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 glycols such as 2,4-trimethyl-1,3-pentanediol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polyoxyalkylene glycols such as polytetramethylene glycol, and bisphenols such as bisphenol A Etc. can be used. In addition, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol and the like can be used in combination as trivalent or higher alcohols.

(2.4) Polyfunctional epoxy compound A polyfunctional epoxy compound can be used for a crosslinking agent, for example. The polyfunctional epoxy compound crosslinks by reacting with the hydroxyl group remaining at the end of the polyurethane during melt kneading with the polyurethane resin. In addition, 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 present at the terminal. In particular, in a polyurethane resin having no terminal hydroxyl group or carboxyl group, or in a polyurethane resin existing only in a trace amount, a polyurethane resin composition can be obtained by using a polyfunctional epoxy compound in combination with the above-mentioned polyvalent amine or polyhydric alcohol. The hardness of an object can be adjusted suitably.

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

(2.5) Heat treatment The polyurethane resin to which the crosslinking agent has been added can be further heat treated to adjust the hardness of the polyurethane resin. In order to advance the crosslinking by the heat treatment, the polyurethane resin to which the crosslinking agent is added can be carried out by holding at a predetermined temperature for a predetermined time. The atmosphere during the heat treatment may be performed in air or in an inert gas such as nitrogen, or under reduced pressure, as 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 electron beam irradiation dose 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, when the value of the electron beam irradiation dose is too small, the hardness of the polyurethane resin composition is not sufficiently high, and when the value of the irradiation dose is too large, the polyurethane resin main chain is more than necessary. It is cut and the hardness decreases. On the other hand, when the irradiation dose of the electron beam is in the above-described preferable range, a sealing material capable of suitably temporarily closing the pores is obtained.

(4) Blending of filler The filler may contain a filler. Examples of the filler include organic or inorganic fibrous reinforcing materials and granular or powder reinforcing materials, and these can be used alone or in combination of two or more.

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

Granular or powdery reinforcing materials include 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 And barium sulfate. The filler may be treated with a bundling material or a surface treatment agent as necessary. By including a filler in the resin composition that forms the pellets and / or powder, the hardness of the resin composition can be further increased.

When the filler is added to the resin composition, the filler is preferably added so that the content of the filler in the resin composition is 2% by weight or more and 30% by weight or less. It is more preferable to add so that it may become 4 wt% or more and 20 wt% or less. Here, when the content of the filler is too small, the hardness of the polyurethane resin composition is not sufficiently high, and when the content of the filler is too large, the filler remains even after decomposition of the polyurethane resin. If you do this, you may not be able to fully unlock the eyes. On the other hand, when the content of the filler in the resin composition is in the above-described preferred range, a strong alkaline well fluid (including a filler containing the resin composition, a xanthan gum, a shale stabilizer, and the like ( Even when muddy water is used, for example, a large fracture having a width of 0.5 mm or more and 10 mm or less can be suitably observed.

The size (diameter, length, etc.) of the filler may be in a range that does not significantly affect the particle size of the filler, and may be, for example, 1 μm or more and 3,000 μm or less, 3 μm or more, 000 μm or less is preferable, and 5 μm or more and 500 μm or less is more preferable.

[Other compounding agents in resin composition]
The sealant according to the present embodiment can further contain various compounding agents that are usually added in the sealant as long as the purpose of the present embodiment is not impaired. Examples thereof include various additives such as a decomposition accelerator, an antioxidant, and a decomposition inhibitor. These various additives can be used alone or in combination of two or more.

(Degradation accelerator)
The sealant may contain a decomposition accelerator. A decomposition accelerator accelerates | stimulates decomposition | disassembly of the resin composition contained in a filler, and can mention 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. Carboxylic acid esters, 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% by weight to 20% by weight, more preferably 0.3% by weight to 15% by weight, and more preferably 0.5% by weight to 10% by weight. % Or less is more preferable. According to the preferable range described above, the decomposition promoting effect is sufficient because the content of the decomposition accelerator is not too small. Moreover, since there is not too much content, initial hardness does not fall and sufficient eye keeping time can be obtained.

<Well fluid>
The well fluid according to the present embodiment includes the above-described sealant.

The well fluid is not particularly limited, and for example, muddy water can be used.

The sealant according to the present embodiment may have a dispersibility and wettability in muddy water, especially in a muddy water, compared to a starch derivative or the like which is one of dehydration reducing agents contained in muddy water. The high dispersibility of the sealant in the well treatment fluid is effective for efficiently locating large fractures, and a tool for injecting the well treatment fluid into the well (for example, a drill and its surroundings). This also contributes to prevention of clogging caused by the sealant in the member. For this reason, the well fluid is preferably an aqueous mud.

The well fluid according to the present embodiment is the type and physical properties of the resin composition contained in the sealant depending on the environment in the wellbore that uses the well fluid, particularly the temperature or pressure of the high temperature environment. The composition (including additives and the like), shape, size, and the like can be appropriately selected and combined. Therefore, the sealant according to the present embodiment may use different materials or combinations of materials.

The content of the aforementioned filler in the well fluid according to the present embodiment is not particularly limited, and is usually 1% by weight to 20% by weight, and preferably 5% by weight to 15% by weight.

The well fluid according to the present embodiment can contain various compounding agents that are usually added in the well fluid, in addition to the above-described sealant, in a range that does not impair the purpose of the present embodiment. For example, inorganic weighting agents such as barite (BaSO ₄ ) and calcium carbonate, alkali metal halides such as NaCl, KCl and CaCl ₂ or alkaline earth metal halides (salts), clay swelling inhibitors, or solid-free specific gravity Organic colloid agents (thickeners) such as regulators, AMPS polymers, xanthan gum, guar gum and carboxymethyl cellulose (CMC), inorganic colloid agents (clays, etc.), dispersed anti-powder agents, surfactants, pH regulators, etc. Anti-mudging agents, conversion agents, antifoaming agents, lubricants, antiseptics, bactericides, anticorrosion agents, etc. are mentioned, and contain them at a concentration according to the environment in the wellbore where the well fluid is used. Can do.

<Well drilling method>
The well excavation method according to the present embodiment performs temporary sealing using the above-described sealing agent.

For example, in the well drilling method according to the present embodiment, the above-described sealant is used as a well such as a shale layer for producing well drilling in a reservoir section using a drill, shale gas / oil, or the like. Can be used in excavation. Further, in the well drilling method according to the present embodiment, the fluid of the filler containing the filler according to the present embodiment is introduced into the well prior to flowing the well fluid into the well hole. It may be allowed to flow.

In addition, depending on the environment in which the sealant according to this embodiment is used, particularly the temperature or pressure of the high temperature environment, the type, physical properties, composition, shape, and size of the resin composition contained in the sealant are determined. It can select suitably and can combine.

<Summary>
The sealant according to an embodiment of the present invention is a sealant that seals a well wall, and the sealant includes pellets and powder formed from a resin composition containing a polyurethane resin, The pellet is characterized by an indentation hardness at 23 ° C. of 37 or more.

Further, in the sealant according to one embodiment of the present invention, the indentation hardness at 23 ° C. of the pellet is preferably 98 or less.

In the sealant according to one embodiment of the present invention, the polyurethane resin is preferably at least one of an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin.

Further, in the sealant according to one embodiment of the present invention, the aliphatic isocyanate constituting the aliphatic isocyanate-based polyurethane resin is hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, hydrogenated xylylene diisocyanate, and dicyclohexyl. Preference is given to at least one aliphatic isocyanate selected from the group consisting of methane diisocyanate.

In the sealant according to one embodiment of the present invention, the aromatic isocyanate constituting the aromatic isocyanate-based polyurethane resin is selected from the group consisting of diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and naphthalene diisocyanate. Preferably it is at least one aromatic isocyanate selected.

In the sealant according to one embodiment of the present invention, it is preferable that at least one of the aliphatic isocyanate polyurethane resin and the aromatic isocyanate polyurethane resin includes a polyester skeleton.

Moreover, in the filler according to one embodiment of the present invention, the resin composition further includes a crosslinking agent,
The content of the crosslinking agent in the resin composition is preferably 0.2% by weight or more and 50% by weight or less.

Moreover, in the sealant according to one embodiment of the present invention, the crosslinking agent is a 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. Preferably, at least one cross-linking agent selected from:

Moreover, in the sealant according to one embodiment of the present invention, the resin composition further includes a filler, and the content of the filler in the resin composition is 2 wt% or more and 30 wt% or less. It is preferable.

In the sealant according to one embodiment of the present invention, the filler is preferably an organic or inorganic fibrous reinforcing material.

In the sealant according to one embodiment of the present invention, the weight ratio of the pellets to the powder is preferably 5:95 to 60:40.

Further, a well fluid according to an embodiment of the present invention is characterized by including the above-mentioned sealant.

Moreover, the well excavation method according to an embodiment of the present invention is characterized in that the sealing is performed temporarily using the above-mentioned sealing agent.

Examples will be shown below, and the embodiments of the present invention will be described 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 detail. The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the respective technical means disclosed herein are also included in the present invention. It is included in the technical scope of the invention. Moreover, all the literatures described in this specification are used as reference.

For Examples 1 to 18 and Comparative Examples 1 to 3, sealants were prepared under the following conditions.

<Example 1>
[Manufacture of sealants for evaluation]
(Manufacture of pellets and powder)
First, as an HDI polyurethane resin having a polybutylene adipate skeleton, 1,800 g of Pandex (registered trademark) T-R3080 manufactured by DIC Covestro Polymer Co., Ltd. was weighed and put into a polyethylene bag. Further, 200 g of MDI as a cross-linking agent was weighed and put into the polyethylene bag. That is, the crosslinking agent was added so that the content with respect to the HDI polyurethane resin after the addition of the crosslinking agent was 10% by weight. After the addition of the cross-linking agent, the HDI polyurethane resin and the cross-linking agent in the polyethylene bag were stirred for 3 minutes by handshaking with a polyethylene bag to obtain a resin composition as a mixture (blend). After obtaining the blend, the blend was melt kneaded at a temperature of 230 ° C. for 5 minutes 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 Chemical Industries, Ltd.)
After making the blend obtained by melt extrusion into a strand, a pellet having a diameter of 2.5 mmφ × length of 3 mm was obtained through a pelletizer. Thus, the maximum length of the long piece of pellet was 3 mm.

(Heat treatment)
The pellets obtained by melt extrusion were heat-treated at 120 ° C. for 12 hours using a hot air forced circulation dryer TDH-3 manufactured by Takasugi Seisakusho.

(Electron beam irradiation to pellets)
Using an electron beam irradiation apparatus manufactured by Nippon Electron Irradiation Service Co., Ltd., the pellets after the heat treatment were irradiated with an electron beam of 60 kGy.

(Indentation hardness measurement)
After irradiating the pellet with an electron beam, the hardness of the pellet was measured under a load of 5 kgf using a hardness meter. As a hardness meter, a durometer type D hardness meter GS-720R manufactured by Teclock Co., Ltd. was used. As shown in Table 3 (Table 3 is divided into two parts. Tables 3-1 and 3-2 are collectively referred to as Table 3 below), the pellets after electron beam irradiation were pressed at 23 ° C. The hardness was 38.

(Pulverization of pellets)
Next, a part of the pellets after the heat treatment was pulverized by a freeze pulverization method by immersion in liquid nitrogen using a pulverizer shown below to prepare a powder. Here, the pellets immersed in liquid nitrogen for 5 minutes and cooled were charged into a pulverizer at 125 g / min, and at the same time, liquid nitrogen was also charged into the pulverizer.
・ Crusher: Exceed Mill EM-1A type (manufactured by Hadano Industry Co., Ltd.)
・ Turntable:
Pin disc diameter: 160mm
Pin diameter: 3.5mm
Pin length: 19mm
Number of pins on main unit side: 178 Main unit side pin arrangement: 3 rows Main unit side pin spacing: 3.5 mm
Number of door side pins: 168 Door side pin arrangement: 3 rows Door side pin spacing: 2.5 mm
・ Crushing rotation speed: Main body side pin disc: 8000 rpm (133 Hz)
-Door side pin disk: 12000rpm (200Hz)
(Measurement of median diameter of powder (50% D))
The median diameter (50% D) of the obtained powder was measured using a SALD3000 manufactured by Shimadzu Corporation, which is a laser diffraction particle size distribution measuring device. As shown in Table 3, the median diameter (50% D) of the powder was 396 μm.

(Manufacture of sealants for evaluation)
7 g of pellets after electron beam irradiation and 28 g of powder were weighed and put into a polyethylene bag, and then stirred for 3 minutes by handshaking to obtain a blend of pellets and powder. Thus, the pellet and the powder were mixed at a weight ratio of 20:80 to obtain an evaluation filler.

[Manufacture of evaluation fluid (hereinafter also referred to as evaluation mud)]
The obtained evaluation filler and each component of Table 1 below were mixed at a weight ratio shown in Table 1 to prepare an evaluation mud.

In addition, the sodium chloride in the 10 weight% sodium chloride aqueous solution in Table 1 is a pure chemical company make. The AMPS polymer is Driscal (registered trademark) -D manufactured by Ternite Co., Ltd. Cross-linked starch is Terpolymer DX manufactured by Ternite Co., Ltd. The oxygen scavenger is Ternite (registered trademark) OS-5 manufactured by Ternite Co., Ltd.

[Evaluation for closing]
The seal evaluation was performed by a seal test using a plug tester (Flitter Press HPHT 500ML manufactured by Fann Instrument Company) including the slot disk shown in FIG. In the sealing test, a slot disk (material: SUS304) having a diameter of 63 mm and a thickness of 6 mm having a rectangular hole having a width of 1 mm and a length of 20 mm was used.

Hereinafter, the sealing test will be described with reference to FIG. FIG. 1 is a diagram schematically showing a plug tester used for a test for evaluating the performance of plugging evaluation mud water.

As shown in FIG. 1, after putting the evaluation muddy water mixed with the evaluation sealant into the plug tester, a pressure of 200 psi was applied to the plug tester from above, and the initial sealability at 23 ° C. was confirmed. Here, the initial sealing property means that by applying pressure from above, it is confirmed whether or not the sealing agent can form a cake layer on the pores of the slot disk. If it was confirmed, it was judged that there was an initial sealing ability.

After confirming the initial sealability, the plug tester was heated from 23 ° C. to 120 ° C. and held with a pressure of 200 psi from above. After raising the temperature, a pressure of 500 psi was applied to the plug tester from above. As a result, a pressure of 500 psi was applied to the slot disk from above.

After the pressure was increased to 500 psi, the sealing test was started while maintaining the temperature and pressure.

Here, as described above, the slot disk has a rectangular hole having a width of 1 mm and a length of 20 mm, and water is transmitted from the container through the hole. Therefore, the amount of water permeated from the filter every predetermined time was measured.

When the amount of permeation increased every predetermined time, the permeation recovery point (the point where the temporary sealing was released) was set, and the sealing test was completed.

The time until the water permeation recovery point is reached after the start of the eye stop test is set as the eye end maintenance time, and when the eye end maintenance time is 1 hour or more and 960 hours (40 days) or less, the eye end evaluation is " “A”, and otherwise, the evaluation was “B”.

In addition, for those having a mesh maintenance time of 12 hours or more at 120 ° C., the measurement of the mesh maintenance time is interrupted every 12 hours, and the following (1) to (3) are performed. Repeated.
(1) In an autoclave container different from the container shown in FIG. 1, the muddy water for evaluation retained in advance from the start of the sealing test at 120 ° C. was taken out from the autoclave container. The composition of the evaluation muddy water is the same as that of the evaluation muddy water in Table 1.
(2) The sealing agent was filtered off from the extracted muddy water for evaluation and washed with water. Since this sealant is held at 120 ° C. from the start of the seal, the sealant deteriorates with time in the container shown in FIG. 1 and is decomposed to the same extent as the sealant in a decomposed state. It can be said that.
(3) A muddy water for evaluation was newly produced using the sealant in a decomposed state, and was put into a container of a new plug tester. After the injection, the measurement of the retention time was resumed. Thus, every 12 hours, the evaluation mud substantially the same as the evaluation mud in the plug tester was put into the container of the plug tester, and the sealing test was continued.

When this method is used, when the water permeation recovery point is observed after the repetition of (1) to (3), the time previously stored in the autoclave container at 120 ° C. and the time after the test is restarted in the plug tester. The sum of the time until the permeable recovery point was observed was taken as the maintenance time.

As a result of conducting the sealing test under the above conditions, the sealing maintenance time at 120 ° C. was 120 hours as shown in Table 3.

<Example 2>
In Example 2, an MDI polyurethane resin having a polycaprolactone skeleton was used in place of the HDI polyurethane resin, these were not subjected to heat treatment, and were not irradiated with an electron beam, as in Example 1. Pellets and powders were made. As the MDI polyurethane resin, Pandex (registered trademark) T-5070 manufactured by DIC Covestro Polymer Co., Ltd. having a durometer type D hardness of 60 at 23 ° C. was used.

As shown in Table 3, the indentation hardness (hardness) of the pellet at 23 ° C. was 68. The median diameter (50% D) of the powder was 334 μm.

Pellets and powder were mixed in the same weight ratio as in Example 1 to prepare an evaluation filler. Further, an evaluation muddy water was produced from the obtained sealing agent for evaluation in the same manner as in Example 1, and a sealing test was performed at 120 ° C. using a slot disk having a width of 1 mm in the same manner as in Example 1. As shown in Table 3, the maintenance time at 120 ° C. was 224 hours.

<Example 3>
In Example 3, MDI was used as a cross-linking agent, 10% by weight of the cross-linking agent was added to the MDI polyurethane resin, and the pellet was treated in the same manner as in Example 1 except that it was heat-treated in the same manner as in Example 1. And powder was produced.

The method for adding the crosslinking agent was as follows. That is, first, 1800 g of MDI polyurethane resin was weighed and put into a polyethylene bag. Further, 200 g of MDI as a cross-linking agent was weighed and put into the polyethylene bag. After the addition of the cross-linking agent, the MDI polyurethane resin and the cross-linking agent in the polyethylene bag were stirred for 3 minutes by handshaking with a polyethylene bag to obtain a blend. The melt extrusion after obtaining the blend was carried out in the same manner as in the above examples.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 73. The median diameter (50% D) of the powder was 402 μm.

The pellets and the powder were similarly mixed at the same weight ratio as in the above-described Examples to produce an evaluation filler. An evaluation muddy water was produced from the obtained sealing agent for evaluation in the same manner as in the above-described example, and a sealing test was performed at 120 ° C. using a slot disk having a width of 1 mm in the same manner as in the above-described example. . As shown in Table 3, the maintenance time at 120 ° C. was 672 hours.

<Example 4>
In Example 4, pellets and powder were prepared in the same manner as in Example 3 except that the addition amount of the crosslinking agent was changed from 10% by weight to 20% by weight.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 73. The median diameter (50% D) of the powder was 203 μm.

Pellets and powder were mixed at a weight ratio of 40:60 to produce a sealant for evaluation. An evaluation muddy water was prepared from the evaluation sealant in the same manner as in the above-described example, and a seal test was performed at 149 ° C. using a slot disk having a width of 1 mm in the same manner as in the above-described example. As shown in Table 3, the maintenance time at 149 ° C. was 3 hours.

<Example 5>
In Example 5, pellets and powder were prepared in the same manner as in Example 4 except that the addition amount of the crosslinking agent was changed from 20% by weight to 30% by weight.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 71. The median diameter (50% D) of the powder was 146 μm.

Pellets and powder were mixed at the same weight ratio as in Example 4 to produce an evaluation filler. From the obtained evaluation sealant, an evaluation muddy water was prepared in the same manner as in the above-described example, and a seal test was performed at 149 ° C. using a slot disk having a width of 1 mm in the same manner as in the above-described example. It was. As shown in Table 3, the maintenance time at 149 ° C. was 4 hours.

<Example 6>
In Example 6, pellets and powder were prepared in the same manner as in Example 2 except that the resin composition used as the base further includes the above-mentioned HDI polyurethane resin in addition to the above MDI polyurethane resin.

More specifically, 1,000 g of the above-mentioned MDI polyurethane resin was weighed and 1,000 g of HDI polyurethane resin was weighed and put into a polyethylene bag. After the addition, handshaking was performed in the same manner as in the above-described example, and the MDI polyurethane resin and the HDI polyurethane resin were stirred to obtain a blend. Thus, the MDI polyurethane resin and the HDI polyurethane resin were mixed at a weight ratio of 50:50. Thereafter, the blend was melt-extruded (melt-kneaded) in the same manner as in the above-described example to obtain pellets and powder.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 38. The median diameter (50% D) of the powder was 352 μm.

Pellets and powder were mixed at a weight ratio of 40:60 to produce a sealant for evaluation. From the obtained evaluation sealant, an evaluation muddy water was prepared in the same manner as in the above-described example, and a seal test was performed at 110 ° C. using a slot disk having a width of 1 mm in the same manner as in the above-described example. It was. As shown in Table 3, the maintenance time at 110 ° C. was 2 hours.

<Example 7>
In Example 7, except that the slot disk width in the plug tester was changed from 1 mm to 3 mm, an evaluation sealant and an evaluation muddy water were produced under the same conditions as in Example 3, and the same as in the above example. The sealing test was conducted at 120 ° C. by the above method.

As shown in Table 3, the maintenance time at 120 ° C. was 168 hours.

<Example 8>
In Example 8, a sealing agent for evaluation and a muddy water for evaluation were prepared under the same conditions as in Example 7 except that a sealing test was performed at 149 ° C. instead of 120 ° C., and the sealing was performed using a slot disk having a width of 3 mm. Evaluation was performed. As shown in Table 3, the eye keeping time at 149 ° C. was 2 hours.

<Example 9>
In Example 9, a sealant for evaluation was prepared in the same manner as in Example 3 except that the pellet and powder were further irradiated with 20 kGy of an electron beam.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 74, and the median diameter (50% D) of the powder was 448 μm.

An evaluation muddy water was produced from the obtained evaluation sealant in the same manner as in the above-described Examples, and the evaluation was performed at 120 ° C. using a slot disk having a width of 3 mm. As shown in Table 3, the maintenance time at 120 ° C. was 4 hours.

<Example 10>
In Example 10, a sealant for evaluation was prepared in the same manner as in Example 9 except that the pellet and powder were irradiated with 60 kGy instead of 20 kGy.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 74, and the median diameter (50% D) of the powder was 402 μm.

An evaluation muddy water was produced from the obtained evaluation sealant in the same manner as in the above-described Examples, and the evaluation was performed at 120 ° C. using a slot disk having a width of 3 mm. As shown in Table 3, the maintenance time at 120 ° C. was 336 hours.

<Example 11>
In Example 11, instead of mixing pellets and powder at a weight ratio of 20:80, an evaluation filler was prepared in the same manner as in Example 10, except that the mixture was mixed at a weight ratio of 40:60.

<Example 12>
In Example 12, a sealing agent for evaluation and a muddy water for evaluation were prepared under the same conditions as in Example 10 except that a sealing test was performed at 149 ° C. instead of 120 ° C., and the sealing was performed using a slot disk having a width of 3 mm. Evaluation was performed. As shown in Table 3, the maintenance time at 149 ° C. was 7 hours.

<Example 13>
In Example 13, a sealant for evaluation was prepared in the same manner as in Example 12 except that 100 kGy was irradiated instead of 60 kGy of the electron beam to the pellets and powder.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 74, and the median diameter (50% D) of the powder was 685 μm.

An evaluation muddy water was produced from the obtained evaluation sealant by the same method as in the above-described example, and the evaluation was performed at 149 ° C. using a slot disk having a width of 3 mm. As shown in Table 3, the maintenance time at 149 ° C. was 5 hours.

<Example 14>
In Example 14, pellets and powder were prepared in the same manner as in Example 12 except that the addition amount of the crosslinking agent was changed from 10% by weight to 20% by weight.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 75. The median diameter (50% D) of the powder was 534 μm.

Pellets and powder were mixed at the same weight ratio as in Example 12 to produce an evaluation filler. From the obtained evaluation sealant, an evaluation muddy water was prepared in the same manner as in the above-described example, and a seal test was performed at 149 ° C. using a slot disk having a width of 3 mm in the same manner as in the above-described example. It was. As shown in Table 3, the maintenance time at 149 ° C. was 4 hours.

<Example 15>
In Example 15, a sealant for evaluation was prepared in the same manner as in Example 14 except that the pellet and powder were irradiated with 100 kGy instead of 60 kGy.

As shown in Table 3, the indentation hardness at 23 ° C. of the pellet was 73, and the median diameter (50% D) of the powder was 580 μm.

An evaluation muddy water was produced from the obtained evaluation sealant by the same method as in the above-described example, and the evaluation was performed at 149 ° C. using a slot disk having a width of 3 mm. As shown in Table 3, the maintenance time at 149 ° C. was 4 hours.

<Example 16>
In Example 16, triallyl isocyanate (TAIC) was used instead of MDI as a crosslinking agent, and the addition amount of the crosslinking agent was changed from 10% by weight to 0.476% by weight (≈0.5% by weight). Produced a sealing agent for evaluation in the same manner as in Example 9.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 63, and the median diameter (50% D) of the powder was 291 μm.

An evaluation muddy water was produced from the obtained evaluation sealant by the same method as in the above-described example, and the evaluation was performed at 149 ° C. using a slot disk having a width of 3 mm. As shown in Table 3, the maintenance time at 149 ° C. was 3 hours.

<Example 17>
[Manufacture of sealants for evaluation]
(Manufacture of pellets)
In Example 17, in order to produce pellets, first, 1,900 g of the above-mentioned MDI polyurethane resin was weighed and put into a polyethylene bag. Further, as a filler, 100 g of 03JAFT592S manufactured by Owens Corning Co., Ltd., glass fiber (GF) having a diameter (D) of 10 μm and an aspect ratio (L / D) of 30 was weighed and put into the polyethylene bag. That is, 5% by weight of a filler was added to the MDI polyurethane resin. After the addition of the filler, the MDI polyurethane resin in the polyethylene bag and the filler were stirred for 3 minutes by handshaking with a polyethylene bag to obtain a blend. After obtaining the blend, it was melt-extruded in the same manner as in the above examples to obtain pellets.

As shown in Table 3, the indentation hardness of the pellet at 23 ° C. was 58.

(Manufacture of powder)
In Example 17, powder was produced under the same conditions as in Example 3. As shown in Table 3, the median diameter (50% D) of the powder was 402 μm.

(Manufacture of sealants for evaluation)
14 g of pellets and 21 g of powder were weighed and put into a polyethylene bag, and then stirred for 3 minutes by handshaking to obtain a blend of pellets and powder. Thus, pellets and powder were mixed at a weight ratio of 40:60 to obtain an evaluation filler.

[Manufacture of evaluation fluid (hereinafter also referred to as evaluation mud)]
The obtained sealant for evaluation and each component of Table 2 below were mixed at a weight ratio shown in Table 2 to prepare a xanthan gum evaluation muddy water as an evaluation muddy water.

The xanthan gum in Table 2 is MI L. L. C. This is DUO-VIS PLUS. The shale stabilizer is MI L.I. L. C. ULTRAHIB made by The disinfectant is MI L.I. L. C. SAFE-CIDE made. Cross-linked starch is terpolymer DX manufactured by Ternite Co., Ltd.

[Evaluation for closing]
In place of the muddy water for evaluation in Examples 1 to 16, the muddy water for xanthan gum evaluation was used and evaluation was performed at 120 ° C. using a slot disk having a width of 3 mm in the same manner as in the above-described example. As shown in Table 3, the maintenance time at 120 ° C. was 72 hours.

<Example 18>
In Example 18, GF-containing powder obtained by pulverizing part of the pellets of Example 17 instead of powder obtained by adding 10% by weight of a MDI crosslinking agent to the MDI-based polyurethane resin. Except that was used, pellets and powder were obtained in the same manner as in Example 17.

As shown in Table 3, the median diameter (50% D) of the powder was 171 μm.

Pellets and powder were mixed at a weight ratio of 40:60 to produce a sealant for evaluation. From the obtained sealing agent for evaluation, a muddy water for xanthan gum evaluation was produced in the same manner as in Example 17, and a sealing test was performed at 120 ° C. using a slot disk having a width of 3 mm in the same manner as in the above-mentioned Examples. It was. As shown in Table 3, the maintenance time at 120 ° C. was 72 hours.

<Comparative Example 1>
In Comparative Example 1, pellets and powder were prepared in the same manner as in Example 1 except that no crosslinking agent was added to the HDI polyurethane resin, the pellet was not heat-treated, and no electron beam was irradiated.

As shown in Table 4, the indentation hardness of the pellet at 23 ° C. was 31. The median diameter (50% D) of the powder was 337 μm.

Pellets and powder were mixed in the same weight ratio as in Example 1 to prepare an evaluation filler. An evaluation muddy water was produced from the obtained sealing agent for evaluation in the same manner as in Example 1, and a sealing test was performed at 110 ° C. using a slot disk having a width of 1 mm in the same manner as in Example 1. As shown in Table 4, the maintenance time at 110 ° C. was 0 hour.

<Comparative example 2>
In Comparative Example 2, an evaluation filler was prepared in the same manner as Comparative Example 1 except that the pellets and powder were mixed at a weight ratio of 40:60 instead of being mixed at a weight ratio of 20:80.

An evaluation mud was prepared from the obtained sealant for evaluation by the same method as in Comparative Example 1, and the seal evaluation was performed at 110 ° C. using a slot disk having a width of 1 mm. As shown in Table 4, the maintenance time at 110 ° C. was 0 hour.

<Comparative Example 3>
In Comparative Example 3, an evaluation sealant and an evaluation muddy water were prepared under the same conditions as in Comparative Example 2 except that a sealing test was performed at 120 ° C. instead of 110 ° C., and a slot disk having a width of 1 mm was used. An eye-opening evaluation was performed. As shown in Table 4, the maintenance time at 120 ° C. was 0 hour.

In Tables 3 and 4, HDI TPU and MDI TPU refer to HDI polyurethane resin and MDI polyurethane resin, respectively.

As is apparent from Tables 3 and 4, as a result of conducting a sealing test using the temporary sealants of Examples 1 to 16, the eye was observed at any of 110 ° C., 120 ° C., and 149 ° C. The stop evaluation was “A”. Therefore, as in Examples 1 to 16, the filler is made of pellets and powder of a resin composition containing a polyurethane resin, and the long pieces of the pellets are larger than 0.8 mm, and the pellets at 23 ° C. When the indentation hardness is 37 or more and the median diameter (50% D) of the powder is 800 μm or less, the pores have a width of 1 mm or 3 mm at a high temperature of 110 ° C., 120 ° C., and 149 ° C. It has been found that a large fracture can be suitably temporarily observed.

Further, as in Examples 17 and 18, even when the evaluation muddy water is xanthan gum evaluation muddy water exhibiting strong alkalinity, the pellets contain GF as a filler, so that the pores are 3 mm at a high temperature of 120 ° C. It turns out that a large fracture with a width can be temporarily spotted.

On the other hand, as in Comparative Examples 1 to 3, a pellet and powder are included, and the pellet and the powder are a resin composition including a polyurethane resin, the long piece of the pellet is larger than 0.8 mm, and the median diameter of the powder Even when (50% D) is 800 μm or less, as long as the indentation hardness of the pellet at 23 ° C. is less than 37, regardless of the weight ratio of the pellet and the powder, the sealing test temperature, etc., the sealing maintenance time Was 0 hours, and it was found that it has no sealing function.

DETAILED DESCRIPTION OF THE INVENTION The present invention can be used as a sealant and well fluid for temporarily closing a large fracture in a high temperature environment such as a deep well.

Claims

A sealant that seals the pit wall,
The filler includes pellets and powder formed from a resin composition containing a polyurethane resin,
The pellet has an indentation hardness at 37 ° C. of 37 or more.
The sealant according to claim 1, wherein the indentation hardness of the pellet at 23 ° C is 98 or less.
3. The filler according to claim 1, wherein the polyurethane resin is at least one of an aliphatic isocyanate-based polyurethane resin and an aromatic isocyanate-based polyurethane resin.
The aliphatic isocyanate constituting 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 sealant according to claim 3, wherein
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 sealant according to claim 3 or 4.
The eye stop according to any one of claims 3 to 5, wherein at least one of the aliphatic isocyanate polyurethane resin and the aromatic isocyanate polyurethane resin contains at least a polyester skeleton. Agent.
The resin composition further includes a crosslinking agent,
The filler according to any one of claims 1 to 6, wherein the content of the crosslinking agent in the resin composition is 0.2 wt% or more and 50 wt% or less.
The cross-linking agent is at least one cross-linking agent 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. The sealant according to claim 7.
The resin composition further includes a filler,
The filler according to any one of claims 1 to 8, wherein the content of the filler in the resin composition is 2 wt% or more and 30 wt% or less.
The filler according to claim 9, wherein the filler is an organic or inorganic fibrous reinforcing material.
The sealant according to any one of claims 1 to 10, wherein a weight ratio of the pellet to the powder is 5:95 to 60:40.
A well fluid containing the filler according to any one of claims 1 to 11.
A well excavation method characterized by performing temporary sealing using the sealing agent according to any one of claims 1 to 11.