CN106381134A

CN106381134A - Drilling fluid additive composition suitable for coal-bed gas wells and its application, water-based drilling fluid and its application

Info

Publication number: CN106381134A
Application number: CN201610729914.0A
Authority: CN
Inventors: 蒋官澄; 贺垠博; 刘冲; 葛庆颖; 杨丽丽; 王勇; 张永清; 王照辉; 程琳; 胡景东
Original assignee: China University of Petroleum Beijing
Current assignee: China University of Petroleum Beijing
Priority date: 2016-08-25
Filing date: 2016-08-25
Publication date: 2017-02-08
Anticipated expiration: 2036-08-25
Also published as: CN106381134B

Abstract

The invention relates to the drilling field of petroleum industry, in particular to a drilling fluid additive composition suitable for coal-bed gas wells and its application, a water-based drilling fluid and its application. The drilling fluid additive composition contains a tackifying and shear strength improving agent, a coating agent and a filtrate reducer, wherein the tackifying and shear strength improving agent is a copolymer containing a structural unit shown as formula (1), a structural unit shown as formula (2) and a structural unit shown as formula (3), the coating agent is a combtype polysaccharide compound, and the filtrate reducer is nanocrystalline cellulose. Through cooperation of the tackifying and shear strength improving agent, the coating agent and the filtrate reducer, the composition provided by the invention can be used as an additive in a solid-free brine drilling fluid so as to endow the brine drilling fluid with the advantage of high penetration rate and low residue rate. (formula (1), formula (2), formula (3)).

Description

It is applied to drilling fluid additive composition and its application and the water-based drilling of coal bed gas well Liquid and its application

Technical field

The present invention relates to the drilling applications of petroleum industry, in particular it relates to a kind of drilling fluid being applied to coal bed gas well adds Plus agent composition and its application and water-base drilling fluid and its application.

Background technology

China's coal bed gas rich reserves, but not yet realize large-scale commercial exploitation, it is the reason one of important Coalbed methane reservoir has high sensitivity characteristic, is easily polluted by outside fluid, solid phase in drilling process, thus blocking coal-bed methane seepage Fissure channel, leads to affect coal bed gas desorption, gas output declines to a great extent.

In the case that foam drilling fluid technology and under-balanced drilling technology are not yet highly popular, bore coal bed gas well at present Solid free brine drilling liquid technology can be adopted, not use bentonite, barite and remaining solid phase particles, and by adding Salt (such as KCl, NaCl etc.) carries out increasing the salt-water drilling fluid of gained, but at present still untapped obtain can be to coal bed gas Well has the solid free brine drilling fluid compared with high-adaptability.

Content of the invention

It is an object of the invention to provide a kind of drilling fluid additive group that can preferably be applied to coal bed gas well drilling well Compound and its application and water-base drilling fluid and its application.

To achieve these goals, the present invention provides a kind of drilling fluid additive composition being applied to coal bed gas well, should Composition contains thickening extracting and cutting agent, coating agent and fluid loss additive, wherein：

Described thickening extracting and cutting agent is containing the construction unit shown in the construction unit shown in formula (1), formula (2) and formula (3) institute The copolymer of the construction unit showing, wherein：

Wherein, R¹、R^1'、R²、R^2'、R⁵、R^5'、R⁴With each R⁷It is each independently selected from the alkyl of H and C1-C8；R³、R⁶And R⁸ It is each independently selected from the alkylidene of C0-C8；X is selected from-NH- or-O-；N is the integer of 1-4；

Described coating agent is combed polysaccharide compound, and the side chain of described combed polysaccharide compound is shown in lower formula (I) Compound and formula (II) shown in compound provide, wherein, described sulfonate polysaccharide class compound is the starch of sulfonation, sulfonation Cellulose compound or the xanthans of sulfonation：

Wherein, L¹、L^1'、L²And L^2'It is each independently selected from the alkyl of H and C1-C6；

Described fluid loss additive is nano-crystal cellulose.

Present invention also offers above-mentioned composition is as the application of the additive in drilling fluid.

Present invention also offers the water-base drilling fluid containing above-mentioned composition.

Present invention also offers application in coal bed gas well drilling well for the above-mentioned water-base drilling fluid.

The composition of the present invention, by the mating reaction of above-mentioned thickening extracting and cutting agent, coating agent and fluid loss additive, can with As additive so that this salt-water drilling fluid obtains rate of penetration height (because of Solid Free, machine in the salt-water drilling fluid of Solid Free Tool with bore hinder little), the advantage of relatively low residue rate, the efficient drilling well of coal bed gas well and low to coalbed methane reservoir can be reached The purpose of injury.

Other features and advantages of the present invention will be described in detail in subsequent specific embodiment part.

Specific embodiment

Hereinafter the specific embodiment of the present invention is described in detail.It should be appreciated that it is described herein concrete Embodiment is merely to illustrate and explains the present invention, is not limited to the present invention.

Herein the end points of disclosed scope and any value are not limited to this accurate scope or value, these scopes or Value should be understood to comprise the value close to these scopes or value.For number range, between the endpoint value of each scope, respectively Between the endpoint value of individual scope and single point value, and can be obtained one or more between single point value with combination with one another New number range, these number ranges should be considered herein specifically to disclose.

The present invention provides a kind of drilling fluid additive composition being applied to coal bed gas well, and said composition contains thickening and carries cuts Agent, coating agent and fluid loss additive, wherein：

Described fluid loss additive is nano-crystal cellulose.

According to the present invention, above-mentioned composition in being added into drilling fluid, in the presence of Solid Free, you can for coal bed gas well Drilling well in, its main cause is that each composition can play good synergy in no bentonitic saltwater environment, so logical Mating reaction between each composition of the composition crossing the present invention, can reach high power auger in the drilling well for coal bed gas well The effect of fast, low reservoir damage.In order to preferably play the mating reaction between each composition, under preferable case, described Thickening extracting and cutting agent, the weight ratio of coating agent and fluid loss additive are for 100：5-50：100-300, preferably 100：6-30：120-200, More preferably 100：7-25：150-180.

According to the present invention, the copolymer as described thickening extracting and cutting agent can be sufficiently spread out strand in salt solution, and phase Mutually it is wound high intensity space grid structure, cut thus even showing good thickening in DWSW liquid system and carrying Performance.Even at a higher temperature, the Efficient Adhesive Promotion that this copolymer provides also can lift DWSW liquid effectively The apparent viscosity of system, yield value and gel strength.Thus by together with other neccessary compositions with the composition of the present invention, being added into In salt-water drilling fluid, can be high, relatively low residual in the drilling well of coal bed gas well, reaching rate of penetration under without solid-phase component The effect of slag rate, to realize efficient drilling well and the Low Damage to coalbed methane reservoir of coal bed gas well.

According to the present invention, wherein, the alkyl of above-mentioned C1-C8 can be for example methyl, ethyl, n-propyl, isopropyl, positive fourth Base, isobutyl group, sec-butyl, the tert-butyl group, n-pentyl, isopentyl, n-hexyl, n-heptyl, n-nonyl etc..

The alkylidene of above-mentioned C0-C8 for example can the alkylidene that formed of alkylidene by C0, the alkyl of above-mentioned C1-C8. Wherein, the alkylidene of C0 can consider is only connecting key or does not exist, and the group at this group two ends will be joined directly together.

In order to preferably play described copolymer as the effect of extracting and cutting agent, under preferable case, as described thickening In the copolymer of extracting and cutting agent, R¹、R^1'、R²、R^2'、R⁵、R^5'、R⁴With each R⁷It is each independently selected from the alkyl of H and C1-C6；R³、 R⁶And R⁸It is each independently selected from the alkylidene of C0-C6；N is the integer of 1-3.

It is highly preferred that R¹、R^1'、R²、R^2'、R⁵、R^5'And R⁴It is each independently selected from the alkyl of H and C1-C4；Each R⁷Each Alkyl independently selected from C1-C6；R³Alkylidene selected from C0-C4；R⁶And R⁸It is each independently selected from the alkylidene of C1-C6.

It is further preferred that R¹、R^1'、R²、R^2'、R⁵、R^5'And R⁴Be each independently selected from H, methyl, ethyl, n-propyl, Isopropyl and normal-butyl；Each R⁷It is each independently selected from methyl, ethyl, n-propyl, isopropyl and normal-butyl；R³Selected from C0's Alkylidene ,-CH₂-、-CH₂-CH₂-、-CH₂-CH₂-CH₂-、-CH(CH₃)-CH₂-、-CH₂-CH(CH₃)-or-CH₂-(CH₂)₂- CH₂-；R⁶And R⁸It is each independently selected from-CH₂-、-CH₂-CH₂-、-CH₂-CH₂-CH₂-、-CH(CH₃)-CH₂-、-CH₂-CH (CH₃)-、-CH₂-(CH₂)₂-CH₂-、-CH₂-CH(CH₃)-CH₂-、-C(CH₃)₂-CH₂-、-CH₂-C(CH₃)₂-、-CH₂-(CH₂)₃- CH₂- and-CH₂-(CH₂)₄-CH₂-.

According to the present invention, in the copolymer as described thickening extracting and cutting agent, under preferable case, the weight average of described copolymer divides Son is measured as 1,000,000-6,000,000g/mol, more preferably 2,000,000-5,500,000g/mol, still more preferably For 2,500,000-5,000,000g/mol, more preferably 3,000,000-4,500,000g/mol, for example, 3,000,000- 4,000,000g/mol.When this copolymer weight average molecular weight within the above range when, particularly 3,000,000-4,500, During 000g/mol scope, the polymer of gained can be well used as extracting and cutting agent, can keep preferable in salt-water drilling fluid Salt resistance and heat-resisting property.The molecular weight distribution index of described copolymer can be for example 1.2-4, preferably 1.5-3.

According to the present invention, in the copolymer as described thickening extracting and cutting agent, although shown in the formula (1) that described copolymer contains The amount of construction unit, the construction unit shown in formula (2) and the construction unit shown in formula (3) can become in wider scope Dynamic, but it is in order at the thickening of copolymer, salt resistance and the heat-resisting property consideration optimizing gained, under preferable case, the knot shown in formula (1) The mol ratio of the construction unit shown in structure unit, formula (2) and the construction unit shown in formula (3) is 10-40：1-10：1, more preferably For 15-30：2-5：1, still more preferably for 18-25：3-4：1.

According to the present invention, in the copolymer as described thickening extracting and cutting agent, described copolymer is understood as a kind of line Property copolymer, can be random, block, alternate, but generally be understood as a kind of linear random copolymer. Although described copolymer can also include some do not affect its as the other structures unit of extracting and cutting agent performance it should be appreciated that , for the sake of convenience, shown in construction unit shown in formula (1) for the described copolymer, the construction unit shown in formula (2) and formula (3) Construction unit constitute, but end group is not particularly limited, but under normal circumstances be hydrogen.

According to the present invention, the copolymer as described thickening extracting and cutting agent can adopt the method for the routine of this area to be obtained, As long as can coordinate with the other compositions of the composition of the present invention, play when in for salt-water drilling fluid preferably to viscosify to carry and cut Effect, is suitable for the drilling well of coal bed gas well.Under preferable case, as the preparation method of the copolymer of described thickening extracting and cutting agent Including：

In aqueous solvent, in the presence of radical initiator and chain-transferring agent, by the (1') shown compound of formula, formula (2') shown compound and the (3') shown compound of formula carry out Raolical polymerizable, wherein,

Wherein, each substituent that the monomer in said method is related to is as described above, will not be described here.Formula (1') the (2') shown compound of shown compound, formula and the (3') shown compound of formula can also be according to described above The specific construction unit species of copolymer properly selected.

Wherein, the instantiation of the (1') shown compound of formula can be for example one of compound shown in following formula Or it is multiple：

In formula (1'-1)：R¹And R^1'For H (also referred to as acrylamide)；In formula (1'-2)：R¹For methyl, R^1'For H (also referred to as Methacrylamide)；In formula (1'-3)：R¹For ethyl, R^1'For H (also referred to as ethyl acrylamide)；Formula (1^'- 4) in：R¹For H, R^1'For methyl (also referred to as 2- crotonamide).

Wherein, the instantiation of the (2') shown compound of formula can be for example one of compound shown in following formula Or it is multiple：

In formula (2'-1)：R⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n=2 (also referred to as NVP)； In formula (2'-2)：R⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n=1；In formula (2'-3)：R⁴、R²And R^2'For H, R³Selected from C0 Alkylidene, n=3；In formula (2'-4)：R⁴、R²And R^2'For H, R³It is selected from-CH₂-, n=2；In formula (2'-5)：R⁴、R²And R^2'For H, R³It is selected from-CH₂-, n=1；In formula (2'-6)：R⁴、R²And R^2'For H, R³It is selected from-CH₂-, n=3.

Wherein, the instantiation of the (3') shown compound of formula can be for example one of compound shown in following formula Or it is multiple：

In formula (3'-1)：R⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-CH₂-CH₂- (also referred to as 3- [N, N- dimethyl-[2- (methacryloxy) ethyl] ammonium] propyl group -1- sulfonate)；

In formula (3'-2)：R⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-CH(CH₃)-CH₂- (also referred to as 3- [N, N- dimethyl-[2- (methacryloxy) ethyl] ammonium] isobutyl group -1- sulfonic acid Salt)；

In formula (3'-3)：R⁵And R^5'For H, X is selected from-NH-, R⁶It is selected from-CH₂-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-CH₂-CH₂- (also referred to as [3- (methacrylamido) propyl group] dimethyl (3- sulfopropyl) ammonium hydroxide)；

In formula (3'-4)：R⁵And R^5'For H, X is selected from-NH-, R⁶It is selected from-CH₂-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-(CH₂)₂-CH₂- (also referred to as [3- (methacrylamido) propyl group] dimethyl (3- thiobutyl) ammonium hydroxide)；

In formula (3'-5)：R⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸It is selected from-CH (CH₃)₂-CH₂- (also referred to as 3- [N, N- dimethyl-[2- (methacryloxy) ethyl] ammonium] tert-butyl group -1- sulfonate).

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, the consumption of above-mentioned monomer is permissible The accounting of the construction unit according to required copolymer and molecular weight are selected, under preferable case, the (1') shown chemical combination of formula The mol ratio of the (2') shown compound of thing, formula and the (3') shown compound of formula is 10-40：1-10：1, more preferably 15- 30：2-5：1, still more preferably for 18-25：3-4：1, for example, 20-25：3-4：1.Anti- in order to be suitable to described radical polymerization The carrying out answering, and reasonably control the molecular weight of copolymer of gained, under preferable case, (1') shown with respect to the formula of 1mol The (2') shown compound of compound, formula and mole total amount of the (3') shown compound of formula, the consumption of described aqueous solvent is 400-1000mL, preferably 400-600mL.Wherein, described aqueous solvent can be single water or miscible have Do not affect the solute (for example, one or more of sodium chloride, potassium chloride, sodium bromide, KBr etc.) of the reaction of the present invention The mixture of water, preferably water certainly.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, described Raolical polymerizable Can be caused using the conventional multiple radical initiators adopting in this area, it is contemplated that anti-between above-mentioned monomer Ying Xing, under preferable case, described radical initiator be 4,4'- azo (4- cyanopentanoic acid), azo diisobutyl amidine hydrochloride, One or more of azo dicyclohexyl formonitrile HCN hydrochloride and azo diisobutyl imidazoline hydrochloride.Described free radical draws The consumption sending out agent can change it is preferable that the (1') shown compound of the formula with respect to 1mol, formula (2') institute in relative broad range The compound showing and mole total amount of the (3') shown compound of formula, the consumption of described radical initiator is 0.1-0.2mmol, It is preferably 0.11-0.14mmol.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, described chain-transferring agent can be adopted With the conventional multiple chain-transferring agents adopting in this area, it is contemplated that the copolymer of more particularly suitable molecular weight can be obtained, excellent In the case of choosing, described chain-transferring agent is selected from one or more of sodium formate, sodium acetate, ammonium hydroxide and urea, more preferably Sodium formate and/or sodium acetate.The consumption of described chain-transferring agent can change it is preferable that with respect to 1mol's in relative broad range The (2') shown compound of the (1') shown compound of formula, formula and mole total amount of the (3') shown compound of formula, described chain turns The consumption moving agent is 0.1-0.2mmol, preferably 0.13-0.15mmol.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, under preferable case, described freedom The condition of base polymerisation includes：Temperature is 40-80 DEG C, and the time is 6-12h.It is highly preferred that described Raolical polymerizable Condition includes：Temperature is 50-70 DEG C, and the time is 7-10h.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, in order in the system of going out Some possible metal ingredients it is preferable that in the preparation method of above-mentioned copolymer, described Raolical polymerizable is also in chelating Carry out in the presence of agent.In this case, by the effect of chelating agent, just can be smoothly through chelation and suppress some possible Metal ion.Described chelating agent for example can be selected from ethylenediamine tetra-acetic acid and its salt (such as sodium ethylene diamine tetracetate), ammonia three second In acid and its salt (sodium ammonium triacetate), hexa metaphosphoric acid and its salt (calgon) and diethylenetriamine penta one Plant or multiple.Preferably, the (2') shown compound of the (1') shown compound of the formula with respect to 1mol, formula and formula are (3') shown Compound mole total amount, the consumption of described chelating agent is 0.01-0.05mmol, more preferably 0.01-0.02mmol.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, in order to keep initiator Deng activity, the method can also include：Described Raolical polymerizable is carried out in an inert atmosphere, for example can be to body It is passed through one or more of nitrogen, helium, neon, argon gas etc. in system and replace atmosphere therein (this process for example can carry out 5- 300min, mainly deoxygenation).

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, in order to better control over The carrying out of above-mentioned Raolical polymerizable is it is preferable that the method includes：First will be (2') shown to the (1') shown compound of formula, formula Compound, the (3') shown compound of formula and aqueous solvent are mixed, and (this mixing condition for example can include in 100- 10-40min is mixed under the mixing speed of 300rpm, at 10-40 DEG C), it is re-introduced into described radical initiator, chain-transferring agent and appoint The chelating agent of choosing is mixed, and under an inert atmosphere (this inert atmosphere formation above described in) carry out as described in oneself By base polymerisation.

According to the present invention, in the preparation method as the copolymer of described thickening extracting and cutting agent, in order to by described copolymerization Thing extracts in product from the reactions above, and the method can also include：By the product of described Raolical polymerizable in 70- 2-5h is dried at 100 DEG C.

According to the present invention, as in the preparation method of the copolymer of described thickening extracting and cutting agent it should be appreciated that above-mentioned side Copolymer prepared by method typically refers to the direct product without purification for the said method (or merely through the above drying Afterwards), the product of even now is probably the mixture of multiple polymers, but the present invention also includes such situation at this In bright scope.

According to the present invention, described combed polysaccharide compound may be considered and connects on the main chain of sulfonate polysaccharide class compound The side chain of the compound shown in formula (I) and the offer of the compound shown in formula (II) on branch, this side chain can be shown in formula (I) Copolymer compound chain shown in compound and formula (II) or be the equal poly chain that compound shown in formula (I) provides respectively With the equal poly chain with the compound shown in formula (II).Described combed polysaccharide compound when for drilling fluid as coating agent, By the multiple spot suction-operated to landwaste for the polar group on strand, effectively the landwaste coalescence of high degree of dispersion is become big grain Footpath particle simultaneously removes during solid controlling, plays excellent encapsulation action, and above-mentioned combed polysaccharide compound can also protected Demonstrate,prove and under preferable encapsulation action, obtain excellent temperature resistance and anti-salt property.And, surprisingly, it is coated compared to linear For agent polymer, the combed polysaccharide compound of the present invention can not only obtain and higher be coated performance, heat-resisting property and anti- Salt performance, additionally it is possible to obtain preferably water-soluble, is so just more applicable for water-base drilling fluid.Thus by the group with the present invention Other neccessary compositions of compound together, are added in salt-water drilling fluid, can be under without solid-phase component, for coal bed gas well In drilling well, reach that rate of penetration is high, the effect of relatively low residue rate, to realize the efficient drilling well of coal bed gas well and coal bed gas stored up The Low Damage of layer.

According to the present invention, wherein, the alkyl of above-mentioned C1-C6 can be for example methyl, ethyl, n-propyl, isopropyl, positive fourth Base, isobutyl group, sec-butyl, the tert-butyl group, n-pentyl, isopentyl, n-hexyl etc..

In order to preferably play described combed polysaccharide compound as the effect of coating agent, under preferable case, R¹、 R^1'、R²And R^2'It is each independently selected from H, methyl, ethyl, n-propyl, isopropyl and normal-butyl.

Wherein, the instantiation of the compound shown in formula (I) can be for example one of compound shown in following formula Or it is multiple：

In formula (I-1)：R¹And R^1'For H (also referred to as acrylamide)；In formula (I-2)：R¹For methyl, R^1'For H (also referred to as first Base acrylamide)；In formula (I-3)：R¹For ethyl, R^1'For H (also referred to as ethyl acrylamide)；In formula (I-4)：R¹For H, R^1'For Methyl (also referred to as 2- crotonamide).

Wherein, the instantiation of the compound shown in formula (II) can be for example one of compound shown in following formula Or it is multiple：

In formula (II-1)：R²And R^2'For H (also referred to as acrylic acid)；In formula (II-2)：R²For methyl, R^2'For H (also referred to as first Base acrylic acid).

According to the present invention, as in the combed polysaccharide compound of described coating agent, described sulfonate polysaccharide class compound is The xanthans of the starch of sulfonation, the cellulose compound of sulfonation or sulfonation.The polysaccharide compound of these sulfonation can be city Sell product, it would however also be possible to employ in the present invention, process described below is prepared.It is considered that the polysaccharide compound of sulfonation is many The structure of some sulfonic groups or other sulfur-containing groups is defined on saccharide compound, this is the conventional cognitive of this area, the present invention Will not be described here.

Wherein, the cellulose compound of described sulfonation be the carboxymethylcellulose calcium of sulfonation, the hydroxymethyl cellulose of sulfonation, The carboxyethyl cellulose of sulfonation, the hydroxypropyl methyl fibre of the hydroxyethyl cellulose of sulfonation, the hydroxypropyl cellulose of sulfonation or sulfonation Dimension element.

According to the present invention, although the present invention to the sulfur-containing group on the polysaccharide compound after sulfonation (as sulfonic group, sulfuric acid Ester group, mercapto etc.) content there is no particular limitation, but be able to obtain the combed polysaccharide being more applicable for coating agent Class compound is it is preferable that in described sulfonate polysaccharide class compound, the content of sulfur-containing group is 20-35 weight %, preferably 25- 30 weight %.

According to the present invention, as in the combed polysaccharide compound of described coating agent, described combed polysaccharide compound Molecular weight can change in relative broad range, in order to obtain the combed polysaccharide compound being more applicable for coating agent, excellent Selection of land, the weight average molecular weight of described combed polysaccharide compound is 9,000,000-15,000,000g/mol, preferably 9,500, 000-14,500,000g/mol, more preferably 10,000,000-13,500,000g/mol, still more preferably for 12,000, 000-13,500,000g/mol.

According to the present invention, as in the combed polysaccharide compound of described coating agent it is preferable that described combed polysaccharide In compound, the content of the construction unit of the compound shown in formula (I) and the offer of the compound shown in formula (II) is 80-95 weight Amount %, preferably 85-92 weight %, more preferably 88-92 weight %.Compound shown in when the formula (I) of offer side chain and formula (II) construction unit of the sulfonate polysaccharide class compound of the construction unit of the compound shown in and offer main chain meets above-mentioned weight Than under, can preferably play the synergy of each group in combed polysaccharide compound, obtain water-soluble high, thus joining Obtain under other neccessary compositions of composition closing the present invention and excellent be coated performance, heat-resisting property and anti-salt property.

According to the present invention, as in the combed polysaccharide compound of described coating agent, although the compound shown in formula (I) and The mol ratio of the construction unit that the compound shown in formula (II) provides can change in relative broad range, it is preferable that formula (I) The mol ratio of the construction unit that the compound shown in shown compound and formula (II) provides is 1：0.2-1, preferably 1：0.2- 0.5, more preferably 1：0.24-0.4 (such as 1：0.25-0.33), still more preferably for 1：0.27-0.33.When shown in formula (I) Compound and formula (II) shown in compound provide construction unit mol ratio within the range when, be obtained in that more favourable In coordinating, with main chain, the side chain playing coating agent performance, as set forth above, it is possible to think that this side chain is that the compound shown in formula (I) carries For equal poly chain and formula (II) shown in compound equal poly chain, but the more preferably compound shown in formula (I) and formula (II) The copolymerization chain that shown compound is formed, particularly random linear copolymerization chain.This several side chain graft is in sulfonate polysaccharide class chemical combination On thing, form comb-type structure, namely the combed polysaccharide compound forming the present invention.

Although there is no particular limitation in the source to the combed polysaccharide compound as described coating agent for the present invention, permissible It is prepared using the conventional method in this area, but be able to be easy to the acquisition of described combed polysaccharide compound, preferably In the case of, the preparation method as the combed polysaccharide compound of described coating agent includes：

(1) in aqueous solvent, polysaccharide compound and sulfonating agent are carried out sulfonating reaction, obtains sulfonate polysaccharide class chemical combination Thing；

(2) in aqueous solvent, in the presence of graft copolymerization catalyst, by shown in sulfonate polysaccharide class compound, formula (I) Compound shown in compound and formula (II) carries out graft copolymerization；

Wherein, described polysaccharide compound is one or more of starch, cellulose compound and xanthans；

Wherein, the compound shown in formula (I) and the compound shown in formula (II) and its group are as described above, This repeats no more.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, step will be led in (1) Crossing described sulfonating reaction provides sulfonate polysaccharide class compound described above, and therefore, described polysaccharide compound can root Selected according to required sulfonate polysaccharide class compound, as one of starch, cellulose compound and xanthans or many Kind.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, the number of described starch Average molecular weight is usually 20,000-200 ten thousand, and it can form sediment for the conventional various native starches in this area, such as potato starch, mung bean One or more of powder, starch from sweet potato, wheaten starch etc..Wherein, described starch optionally containing it catabolite in acid, For example can one or more of the glucose containing dextrin, maltose and its more low-molecular-weight.

Wherein, described cellulose compound is carboxymethylcellulose calcium, hydroxymethyl cellulose, carboxyethyl cellulose, hydroxyl second One or more of base cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose.It should be understood that described polysaccharide Compound is usually linear macromolecular it is believed that the polysaccharide compound after the sulfonation of following gained is also linear big point Minor structure.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, described polysaccharide The molecular weight of compound can be selected according to required sulfonate polysaccharide class compound, such as be 9 in order to prepare weight average molecular weight, 000,000-15,000,000g/mol (preferably 9,500,000-14,500,000g/mol, more preferably 10,000,000- 13,500,000g/mol, still more preferably for 12,000,000-13,500,000g/mol) combed polysaccharide compound, Preferably, the weight average molecular weight of described polysaccharide compound is 100,000-2,000,000g/mol, preferably 150,000-1, 000,000g/mol, for example, 700,000-1,000,000g/mol.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, described aqueous solvent Can be solvent (for example, methyl alcohol, ethanol, the second of single water or the miscible reaction having some not affect the present invention One or more of glycol, propyl alcohol, isopropanol etc.) water mixture, preferably water certainly.It is applied in order to prepare Sulfonate polysaccharide class compound needed for the present invention it is preferable that in step (1), with respect to the described polysaccharide chemical combination of 100 weight portions Thing, the consumption of aqueous solvent is 1000-5000 weight portion, preferably 2000-4000 weight portion.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, to described sulfonating agent There is no particular limitation, as long as the sulfonate polysaccharide class compound of the present invention can be obtained, can be conventional using this area Various sulfonating agents are it is preferable that described sulfonating agent is that (concentration is for example for chlorosulfonic acid, sulfur trioxide, PS and the concentrated sulfuric acid One or more of more than 90 weight %, the concentrated sulfuric acid of particularly 98 weight %).The consumption of described sulfonating agent can be relatively Change in wide scope, the content in order to sulfur-containing group is obtained is the sulfonation of 20-35 weight % (preferably 25-30 weight %) Polysaccharide compound, under preferable case, with respect to the described polysaccharide compound of 100 weight portions, the consumption of described sulfonating agent is 20-40 weight portion, preferably 25-35 weight portion, for example, 28-30 weight portion.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, under preferable case, institute The condition stating sulfonating reaction includes：Temperature is 50-70 DEG C (preferably 55-65 DEG C), and the time is 8-20h (preferably 10-12h).

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, described in order to promote Dissolubility in aqueous solvent for the polysaccharide compound, above-mentioned sulfonating reaction is carried out also in the presence of cosolvent, described cosolvent Can be for example one or more of formic acid, acetic acid, ethanedioic acid and malonic acid.Wherein it is preferred to, with respect to 100 weight portions Described polysaccharide compound, the consumption of described cosolvent is 8-20 weight portion, preferably 10-15 weight portion.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, above-mentioned steps (1) can Using first mixing described polysaccharide compound and aqueous solvent, then to introduce sulfonating agent and the mixing of optional cosolvent gone forward side by side The mode of the described sulfonating reaction of row.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, although step (1) institute The product of the sulfonating reaction obtaining can be used in step (2) without any further process, but is able to more favourable In the carrying out of described graft copolymerization, this step (1) also includes for the product of described sulfonating reaction carrying out separation of solid and liquid (for example By the way of suction filtration) and gained solid phase is dried, thus obtaining the process of sulfonate polysaccharide class compound.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, step is passed through in (2) Compound shown in sulfonate polysaccharide class compound, formula (I) and the compound shown in formula (II) are carried out graft copolymerization, you can The polymer side that compound shown in formula (I) and the compound shown in formula (II) are formed is grafted on sulfonate polysaccharide class compound Chain, it is believed that sulfonate polysaccharide class compound here here does not occur self-polymerization to react, is only in step (1) gained On the basis of sulfonate polysaccharide class compound, pass through the graft copolymerization of step (2) again with this sulfonate polysaccharide class compound for main chain The polymer lateral chain of the compound shown in formula (I) and the formation of the compound shown in formula (II) in grafting.Although shown in described formula (I) Compound and formula (II) shown in the consumption of compound can be according to the side chain situation on required combed polysaccharide compound Properly selected, under preferable case, with respect to the described sulfonate polysaccharide class compound of 100 weight portions, the change shown in formula (I) Total consumption of the compound shown in compound and formula (II) is 500-1500 weight portion, preferably 800-1000 weight portion, more preferably For 850-950 weight portion.Can be with the side chain of main chain preferably cooperation it is preferable that the chemical combination shown in formula (I) in order to obtain The mol ratio of the consumption of compound shown in thing and formula (II) is 1：0.2-1, preferably 1：0.2-0.5, more preferably 1：0.24- 0.4 (such as 1：0.25-0.33), still more preferably for 1：0.27-0.33.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, containing in step (2) Carrying out as described above selects aqueous solvent, and in order to prepare the combed polysaccharide compound being applied to needed for the present invention, Preferably, in step (2), with respect to the described sulfonate polysaccharide class compound of 100 weight portions, the consumption of aqueous solvent is 5000- 10000 weight portions, preferably 6000-9000 weight portion, more preferably 6500-8000 weight portion.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, described graft copolymerization Catalyst can be many using the conventional catalyst for graft copolymerization in this area, the sulfonation in order to preferably be applied to the present invention The graft copolymerization that compound shown in saccharide compound, formula (I) and the compound shown in formula (II) are carried out, preferable case Under, described graft copolymerization catalyst is one or more of high-valency metal compound and persulfate.Wherein, described high price gold Belonging to compound can be for example ceric compound, cobaltous compound, the compound of pentavalent vanadium, ferric compound Deng one or more of, preferably ammonium ceric nitrate, ferric trichloride, in four (4- carboxyl phenyl) Cob altporphyrin and vanadium acetylacetonate One or more.Preferably, described persulfate is one or more of ammonium persulfate, sodium peroxydisulfate and potassium peroxydisulfate.Institute The consumption stating graft copolymerization catalyst can be adjusted it is preferable that with respect to 100 according to required combed polysaccharide compound The described sulfonate polysaccharide class compound of weight portion, the consumption of described graft copolymerization catalyst is 0.1-2 weight portion, preferably 0.2- 1 weight portion, more preferably 0.2-0.5 weight portion.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, under preferable case, step Suddenly, in (2), the condition of described graft copolymerization includes：Temperature be 10-40 DEG C (preferably 20-35 DEG C, for example, 25-35 DEG C), the time is 10-30h (preferably 16-25h, for example, 20-24h).

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, in order to keep The activity of catalyst etc., the method can also include：Described graft copolymerization is carried out in an inert atmosphere, for example permissible It is passed through one or more of nitrogen, helium, neon, argon gas etc. and replace atmosphere therein (this process for example can be entered in system Row 5-300min, mainly deoxygenation).

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, in order to more Fully react, step (2) can then introduce formula (I) institute using first mixing sulfonate polysaccharide class compound and aqueous solvent Compound shown in the compound showing and formula (II) is mixed, and a kind of or many being passed through nitrogen, helium, neon, argon gas etc. After planting and replace atmosphere therein, introduce described graft copolymerization catalyst and carry out described graft copolymerization.

According to the present invention, in the preparation method as the combed polysaccharide compound of described coating agent, the method is acceptable It is dried including by the product of described graft copolymerization, thus obtaining described combed polysaccharide compound.It should be understood that It is that the combed polysaccharide compound prepared by said method typically refers to said method and gained direct is dried without purification Product, the product of even now is probably the mixture of multiple combed polysaccharide compounds, but the present invention is also by such feelings Condition is included within the scope of the invention.

According to the present invention, in order to obtain more excellent filtrate loss controllability, as the described nano-crystal fiber of described fluid loss additive The average grain diameter of element is preferably 100-600nm, more preferably 150-320nm.

Preferably, described nano-crystal cellulose is bar-shaped.

In the present invention, nano-crystal fiber is measured using the transmission electron microscope (TEM) of Japanese JEOL company model JEM-2100 The microscopic pattern of crude granule and average grain diameter.Sample preparation methods：The nano-crystal cellulose that concentration is 0.1 weight % will be diluted to Aqueous dispersions drip in the copper micro-grid of carbon film covering, and are dried with infrared lamp.

According to the present invention, described nano-crystal cellulose can be obtained it is also possible to pass through art technology by way of commercially available Preparing, for example, described nano-crystal cellulose is prepared method known to personnel by the following method：

(1) microcrystalline cellulose is mixed with acid solution；(2) mixture obtaining step (1) is contacted with water, then The product of gained is carried out separation of solid and liquid.

According to said method, in the preparation method of described nano-crystal cellulose, in step (1), microcrystalline cellulose is molten with acid The purpose of liquid mixing is the noncrystalline domain making acid solution penetrate into microcrystalline cellulose, to accelerate the hydrolysis of microcrystalline cellulose.At this In bright, the condition of described mixing includes：The temperature of mixing is 30-70 DEG C, preferably 35-60 DEG C；The time of mixing is 1-15h, It is preferably 3-10h.Described mixing is preferably realized by homogenizer, and rotating speed can turn/min for 100-300.

According to said method, in the preparation method of described nano-crystal cellulose, in step (1), described microcrystalline cellulose and institute The weight ratio stating acid solution can change in wider scope, as long as microcrystalline cellulose can be made to hydrolyze.Typically Ground, described microcrystalline cellulose can be 1 with the weight ratio of described acid solution：20-40, preferably 1：20-30.Described acid solution Concentration can be 30-80 weight %, preferably 50-70 weight %.

According to said method, in the preparation method of described nano-crystal cellulose, the acid in described acid solution can be various normal The inorganic acid of the amorphous area that can penetrate into microcrystalline cellulose of rule or organic acid.In the present invention, described inorganic acid can be normal The various inorganic acids of rule, for example, can be one or more of hydrochloric acid, sulfuric acid, phosphoric acid and nitric acid；Described organic acid can be Conventional various organic acids, such as carbon number are unitary or the binary organic carboxyl acid of 1-5, are specifically as follows formic acid, acetic acid, wine One or more of stone acid and citric acid.

In the present invention, in the preparation method of described nano-crystal cellulose, described microcrystalline cellulose can be by commercially available side Formula obtains.In order to obtain the nano-crystal cellulose grain with specific dimensions, under preferable case, described microcrystalline cellulose crude granule flat All particle diameter is 20-80 μm, more preferably 20-50 μm.

According to said method, in the preparation method of described nano-crystal cellulose, in step (2), mixing that step (1) is obtained The purpose that thing is contacted with water is to terminate the hydrolysis of microcrystalline cellulose with water.Microcrystalline cellulose with respect to 100 weight portions Element, the consumption of water can be 2000-7500 weight portion, preferably 4000-7500 weight portion.

According to said method, in the preparation method of described nano-crystal cellulose, described in step (2), the method for separation of solid and liquid can Think various conventional solid-liquid separating methods in this area, for example, can be filtration separation and/or centrifugation.Preferable case Under, described separation of solid and liquid is centrifugation.In the present invention, to the condition of described centrifugation, there is no particular limitation, as long as permissible Gained suspension is separated and obtains crystal and liquid phase.The condition of centrifugation includes：The rotating speed of centrifugation is 3000-11000 Turn/min, preferably 6000-11000 turns/min；Centrifugation time is 5-30min, preferably 10-20min.

In the preparation method of described nano-crystal cellulose, in order to avoid the impact to follow-up filtrate reducing effect for the remaining acid, on The pH value that the method for stating preferably includes to be washed the solid being centrifugally separating to obtain with water the liquid until being centrifuged gained is 6-7, Then it is dried.The condition of described drying includes：The temperature being dried is 100-110 DEG C, and the time being dried is 8-12h.

According to the present invention, described compositions of additives can also containing the conventional additive for drilling fluid in this area, One or more of Waterproof lock agent, heavy weight additive, gel breaker etc. for example can be included.These other additives are being added to brill It is believed that being formation drilling fluid in the form of the compositions of additives of the present invention when in well liquid, it is of course also possible to be considered this Other additives are independently as the composition of drilling fluid a bit, rather than are considered as the composition of the composition of the present invention, and this all includes Within the scope of the invention.

According to the present invention, described water-base drilling fluid contains the compositions of additives of the present invention, it is possible to obtain rate of penetration height, The effect of relatively low residue rate, to realize efficient drilling well and the Low Damage to coalbed methane reservoir of coal bed gas well.Under preferable case, With respect to the water in the described water-base drilling fluid of 100 weight portions, the content of described composition is 3-10 weight portion, preferably 4-8 Weight portion, more preferably 5-6 weight portion.In the case of satisfaction is somebody's turn to do, with respect in the described water-base drilling fluid of 100 weight portions Water, the content of described thickening extracting and cutting agent is preferably 1.5-5 weight portion, preferably 2-3 weight portion.In the case of satisfaction is somebody's turn to do, relatively Water in the described water-base drilling fluid of 100 weight portions, the content of described coating agent is preferably 0.1-0.5 weight portion, preferably 0.15-0.3 weight portion.In the case of satisfaction is somebody's turn to do, with respect to the water in the described water-base drilling fluid of 100 weight portions, described fall filter The content losing agent is preferably 1-5 weight portion, preferably 3-4 weight portion.

According to the present invention, in addition to the compositions of additives and water of the present invention, described water-base drilling fluid can contain this The various conventional additives adopting in the water-base drilling fluid in field, for example, one of Waterproof lock agent, heavy weight additive etc. or many Kind.Particularly, described water-base drilling fluid is salt-water drilling fluid, thus containing the salt as heavy weight additive, and do not contain other solid phases (such as bentonite, barite etc.), is a kind of salt-water drilling fluid of Solid Free.

Wherein, the salt as heavy weight additive can adjust the density of drilling fluid and reaches desired density, for example can for KCl, One or more of NaCl, KBr and NaBr etc..Preferably, with respect to the water in the water-base drilling fluid of 100 weight portions, as The content of the salt of heavy weight additive is 5-10 weight portion.

Wherein, described Waterproof lock agent has the effect reducing drilling fluid surface tension, preventing Water-blocking damage, for example, can be One of Waterproof lock agent disclosed in polyoxethylene octylphenyl phenol ether, polyoxyethylated alkyl phenol and CN102887974A etc. Or it is multiple.Preferably, with respect to the water in the water-base drilling fluid of 100 weight portions, the content of described Waterproof lock agent is 0.1-0.5 weight Amount part.

The various materials that above-mentioned additive is can be commercially available product it is also possible to be obtained according to the conventional method in this area, this In repeat no more.

According to the present invention, the salt-water drilling fluid of described water-base drilling fluid, particularly Solid Free, it is obtained in that higher machinery Drilling speed, relatively low residue rate, can preferably be applied to the drilling well of coal bed gas well so that the efficient drilling well of coal bed gas well and to coal The Low Damage of layer gas reservoir.

Hereinafter will be described the present invention by embodiment.

In following examples and comparative example, weight average molecular weight and molecular weight distributing index are using (the experiment of GPC gel chromatography Instrument is the gel permeation chrommatograph of waters company of the U.S., model E2695) measure.

In following preparation example, the computing formula of the yield of nano-crystal cellulose：

In following preparation example, the transmission electron microscope (TEM) using Japanese JEOL company model JEM measures nano-crystal cellulose particles The microscopic pattern of grain and average grain diameter.The preparation method of sample：The water of the nano-crystal cellulose that concentration is 0.1 weight % will be diluted to In the copper micro-grid that dispersant liquid drop covers to carbon film, and dried with infrared lamp.

Fluid loss additive preparation example 1

(1) 40g microcrystalline cellulose (purchased from Hubei Zhong Liao Chemical Co., Ltd., the average grain diameter of particle is 20 μm) is added Concentration is in the 700mL aqueous sulfuric acid of 64 weight %, and with rotating speed high-speed stirred 3h of 250 turns/min at 45 DEG C；

(2) add 3L deionized water in the mixture obtaining to step (1) to terminate the hydrolysis of microcrystalline cellulose；Will The suspension obtaining is centrifuged 20min under 11000r/min, is then washed with deionized for several times by the solid of centrifugation gained, directly The pH value of the clear liquid obtaining to centrifugation is 7；The solid cleaned is dried 12h at 105 DEG C, that is, obtains the nano-crystal fiber of 35.28g Element, as fluid loss additive N1, yield is 88.2%.Measure the average grain diameter of product nano-crystal cellulose by transmission electron microscope (TEM) For 239nm, nano-crystal cellulose is bar-shaped.

Thickening extracting and cutting agent preparation example 1

By the acrylamide of 1mol total amount, NVP and 3- [N, N- dimethyl-[2- (methacryloxypropyl Base) ethyl] ammonium] (mol ratio is 25 to propyl group -1- sulfonate：4：1) it is added in the water of 500mL, stir at 150rpm, 30 DEG C Mixing 30min；And add the disodium ethylene diamine tetraacetate of 0.01mmol, the 4,4'- azo of 0.12mmol backward in this mixture (4- cyanopentanoic acid) and the sodium acetate of 0.14mmol, and it is passed through nitrogen 15min with deoxygenation；At 60 DEG C, then carry out polymerisation 8h；Polymerizate is dried at 90 DEG C 2.5h, pulverizes and obtain copolymer, as extracting and cutting agent A1.The Weight-average molecular of this polymer Measure as 4,000,000g/mol, molecular weight distribution index is 1.5, through infrared, proton nmr spectra and the detection of carbon analysis of spectrum, formula (1) construction unit (R shown in¹And R^1'For H), the construction unit (R shown in formula (2)⁴、R²And R^2'For H, R³Alkylene selected from C0 Base, n=2) and formula (3) shown in construction unit (R⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is first Base, R⁸It is selected from-CH₂-CH₂-CH₂-) mol ratio be 25：3.75：1.

Thickening extracting and cutting agent preparation example 2

By the Methacrylamide of 1mol total amount, NVP and [3- (methacrylamido) propyl group] two (mol ratio is 20 to methyl (3- sulfopropyl) ammonium hydroxide：4：1) it is added in the water of 500mL, stir at 200rpm, 30 DEG C Mixing 30min；And add the disodium ethylene diamine tetraacetate of 0.01mmol, azo two isobutyl of 0.14mmol backward in this mixture Amidine hydrochloride and the sodium formate of 0.15mmol, and it is passed through nitrogen 20min with deoxygenation；At 50 DEG C, then carry out polymerisation 10h； Polymerizate is dried at 80 DEG C 3h, pulverizes and obtain copolymer, as extracting and cutting agent A2.The weight average molecular weight of this polymer is 3, 200,000g/mol, molecular weight distribution index is 2.2, through infrared, proton nmr spectra and the detection of carbon analysis of spectrum, shown in formula (1) Construction unit (R¹For methyl, R^1'For H), the construction unit (R shown in formula (2)⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n =2) and the construction unit (R shown in formula (3)⁵And R^5'For H, X is selected from-NH-, R⁶It is selected from-CH₂-CH₂-CH₂-, R⁷It is methyl, R⁸ It is selected from-CH₂-CH₂-CH₂-) mol ratio be 18：3.2：1.

Thickening extracting and cutting agent preparation example 3

By the acrylamide of 1mol total amount, NVP and 3- [N, N- dimethyl-[2- (methacryloxypropyl Base) ethyl] ammonium] (mol ratio is 25 to propyl group -1- sulfonate：4：1) it is added in the water of 400mL, stir at 200rpm, 40 DEG C Mixing 20min；And add the disodium ethylene diamine tetraacetate of 0.02mmol, the 4,4'- azo of 0.12mmol backward in this mixture (4- cyanopentanoic acid) and the sodium acetate of 0.14mmol, and it is passed through nitrogen 10min with deoxygenation；At 70 DEG C, then carry out polymerisation 7h；Polymerizate is dried at 90 DEG C 5h, pulverizes and obtain copolymer, as extracting and cutting agent A3.The weight average molecular weight of this polymer For 3,000,000g/mol, molecular weight distribution index is 2.8, through infrared, proton nmr spectra and the detection of carbon analysis of spectrum, formula (1) Shown construction unit (R¹And R^1'For H), the construction unit (R shown in formula (2)⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n =2) and the construction unit (R shown in formula (3)⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸ It is selected from-CH₂-CH₂-CH₂-) mol ratio be 22：3.5：1.

Thickening extracting and cutting agent preparation example 4

Method according to thickening extracting and cutting agent preparation example 1, except for the difference that, as the consumption of the water of the solvent of reaction system For 1000mL, thus finally pulverize obtaining copolymer, as extracting and cutting agent A4.The weight average molecular weight of this polymer is 2,400, 000g/mol, molecular weight distribution index is 1.7, through infrared, proton nmr spectra and the detection of carbon analysis of spectrum, the knot shown in formula (1) Structure unit (R¹And R^1'For H), the construction unit (R shown in formula (2)⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n=2) and formula (3) construction unit (R shown in⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-CH₂-CH₂-) mol ratio be 25：3.75：1.

Thickening extracting and cutting agent preparation example 5

According to viscosifying the method described in extracting and cutting agent preparation example 1, except for the difference that, the polymerisation carrying out after logical nitrogen deoxygenation Temperature is 30 DEG C, thus finally pulverize obtaining copolymer, as extracting and cutting agent A5.The weight average molecular weight of this polymer is 5,100, 000g/mol, molecular weight distribution index is 2.0, through infrared, proton nmr spectra and the detection of carbon analysis of spectrum, the knot shown in formula (1) Structure unit (R¹And R^1'For H), the construction unit (R shown in formula (2)⁴、R²And R^2'For H, R³Selected from the alkylidene of C0, n=2) and formula (3) construction unit (R shown in⁵For methyl, R^5'For H, X is selected from-O-, R⁶It is selected from-CH₂-CH₂-, R⁷It is methyl, R⁸Selected from- CH₂-CH₂-CH₂-) mol ratio be 25：3.9：1.

Thickening extracting and cutting agent preparation comparative example 1

Method according to thickening extracting and cutting agent preparation example 1, except for the difference that, does not adopt 3- [N, N- dimethyl-[2- (methyl Acryloxy) ethyl] ammonium] propyl group -1- sulfonate, but be 6 using mol ratio：1 acrylamide and N- vinyl pyrrole Alkanone is as monomer, and total consumption of monomer is 1mol, thus copolymer, as extracting and cutting agent DA1 are obtained.The weight average of this polymer Molecular weight is 4,400,000g/mol, and molecular weight distribution index is 1.6.

Thickening extracting and cutting agent preparation comparative example 2

Method according to thickening extracting and cutting agent preparation example 1, except for the difference that, does not adopt NVP, but It is 25 using mol ratio：1 acrylamide and 3- [N, N- dimethyl-[2- (methacryloxy) ethyl] ammonium] propyl group -1- Sulfonate is as monomer, and total consumption of monomer is 1mol, thus copolymer, as extracting and cutting agent DA2 are obtained.The weight of this polymer Average molecular weight is 3,200,000g/mol, and molecular weight distribution index is 2.4.

Coating agent preparation example 1

(1) by the starch of 100g, (purchased from Sa En chemical technology (Shanghai) Co., Ltd., molecular weight is 1,000,000g/ Mol) it is dissolved in the water of 3000g, and adds the acetic acid of 12g and the chlorosulfonic acid of 30g, after stirring, react 12h at 60 DEG C； Products therefrom is carried out suction filtration, and gained solid is dried, thus obtaining sulfonated starch SS-1.Through the identification of infrared nuclear-magnetism, this sulfonation In starch, the content of sulfur-containing group is 28.5 weight %；

(2) the sulfonated starch SS-1 of 100g is dissolved in the water of 7000g, and adds the acrylamide of 700g and the third of 200g Olefin(e) acid, leads to nitrogen 15min after stirring, is subsequently adding the ammonium ceric nitrate of 0.2g, and reacts 24h at 25 DEG C, thus by institute Obtain product to be dried, pulverize, obtain combed polysaccharide compound, as coating agent C1.The weight of this combed polysaccharide compound Average molecular weight is 13,500,000g/mol, wherein, through the identification of infrared nuclear-magnetism, forms the propylene of combed polysaccharide compound side chain The mol ratio of the construction unit of acid amides and acrylic acid offer is 1：0.27, the construction unit being provided by acrylamide and acrylic acid Content is 90 weight %.

Coating agent preparation example 2

(1) by the carboxymethylcellulose calcium of 100g (purchased from Sa En chemical technology (Shanghai) Co., Ltd., molecular weight is 700, 000g/mol) it is dissolved in the water of 2000g, and adds the acetic acid of 12g and the chlorosulfonic acid of 30g, after stirring, react at 55 DEG C 10h；Products therefrom is carried out suction filtration, and gained solid is dried, thus obtaining sulfonation carboxymethylcellulose calcium SC-1.Through infrared nuclear-magnetism Identification, in this sulfonation carboxymethylcellulose calcium, the content of sulfur-containing group is 29.1 weight %；

(2) the sulfonation carboxymethylcellulose calcium SC-1 of 100g is dissolved in the water of 8000g, and add 710g acrylamide and The acrylic acid of 240g, leads to nitrogen 20min after stirring, is subsequently adding the ammonium persulfate of 0.5g, and reacts 22h at 25 DEG C, Thus being dried products therefrom, pulverizing, obtain combed polysaccharide compound, as coating agent C2.This combed polysaccharide The weight average molecular weight of compound is 12,500,000g/mol, wherein, through the identification of infrared nuclear-magnetism, forms combed polysaccharide compound side The mol ratio of the construction unit of the acrylamide of chain and acrylic acid offer is 1：0.3, the knot being provided by acrylamide and acrylic acid The content of structure unit is 90.5 weight %.

Coating agent preparation example 3

(1) by the hydroxypropyl methyl cellulose of 100g, (purchased from Sa En chemical technology (Shanghai) Co., Ltd., molecular weight is 150,000g/mol) it is dissolved in the water of 2000g, and adds the acetic acid of 15g and the sulfur trioxide of 28g, after stirring, in 55 DEG C Lower reaction 10h；Products therefrom is carried out suction filtration, and gained solid is dried, thus obtaining sulfonation hydroxypropyl methyl cellulose SC-2. Through the identification of infrared nuclear-magnetism, in this sulfonation hydroxypropyl methyl cellulose, the content of sulfur-containing group is 25.6 weight %；

(2) the sulfonation hydroxypropyl methyl cellulose SC-2 of 100g is dissolved in the water of 6500g, and adds the methyl-prop of 720g Acrylamide and the methacrylic acid of 230g, lead to nitrogen 10min after stirring, are subsequently adding the ammonium persulfate of 0.5g, and in 30 React 20h at DEG C, thus products therefrom being dried, pulverizing, obtain combed polysaccharide compound, as coating agent C3.Should The weight average molecular weight of combed polysaccharide compound is 12,000,000g/mol, wherein, through the identification of infrared nuclear-magnetism, forms combed many The mol ratio of the construction unit of the Methacrylamide of saccharide compound side chain and methacrylic acid offer is 1：0.31, by methyl The content of the construction unit of acrylamide and methacrylic acid offer is 90.5 weight %.

Coating agent preparation example 4

(1) step according to embodiment 1 (1) prepares sulfonated starch SS-1；

(2) step according to embodiment 1 (2), except for the difference that, the consumption of the acrylamide of employing is 620g, acrylic acid Consumption is 180g, thus finally giving combed polysaccharide compound, as coating agent C4.The weight average of this combed polysaccharide compound Molecular weight is 9,500,000g/mol, wherein, through the identification of infrared nuclear-magnetism, forms the acrylamide of combed polysaccharide compound side chain The mol ratio of the construction unit providing with acrylic acid is 1：0.26, the content of the construction unit being provided by acrylamide and acrylic acid For 88.9 weight %.

Coating agent preparation example 5

(1) step according to embodiment 1 (1) prepares sulfonated starch SS-1；

(2) step according to embodiment 1 (2), except for the difference that, the consumption of the acrylamide of employing is 880g, acrylic acid Consumption is 220g, thus finally giving combed polysaccharide compound, as coating agent C5.The weight average of this combed polysaccharide compound Molecular weight is 14,500,000g/mol, wherein, through the identification of infrared nuclear-magnetism, forms the acryloyl of combed polysaccharide compound side chain The mol ratio of the construction unit of amine and acrylic acid offer is 1：0.24, the containing of the construction unit being provided by acrylamide and acrylic acid Measure as 91.7 weight %.

Coating agent prepares comparative example 1

Using the sulfonated starch SS-1 of step (1) gained of coating agent preparation example 1 as coating agent DC1.

Coating agent prepares comparative example 2

(1) step according to coating agent preparation example 1 (1) prepares sulfonated starch SS-1；

(2) step according to coating agent preparation example 1 (2), except for the difference that, do not adopt acrylic acid, and the use by acrylamide Amount increases to 900g, thus finally giving combed polysaccharide compound, as coating agent DC2.This combed polysaccharide compound Weight average molecular weight is 14,000,000g/mol, and wherein, through the identification of infrared nuclear-magnetism, the side chain in this combed polysaccharide compound is only There is provided by acrylamide, and the content of the construction unit being provided by acrylamide is 90 weight %.

Coating agent comparative example 3

The polyacrylamide that weight average molecular weight purchased from the Tian Run chemical company AB1000 trade mark is 10,600,000g/mol As coating agent DC3.

Embodiment 1

The present embodiment is used for composition and the water-base drilling fluid of the present invention is described.

Water-based drilling formula of liquid：The water of 100 weight portions, the fluid loss additive N1 of 3.5 weight portions, extracting and cutting agent A1 of 2 weight portions, The coating agent C1 of 0.15 weight portion, Waterproof lock agent (the polyoxy second purchased from Jinan Ying Chu Chemical Industry Science Co., Ltd of 0.4 weight portion Alkene octyl phenol ether), the KCl of 5 weight portions；Thus obtaining drilling fluid Y1, its density is 1.1g/cm³.

Embodiment 2

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent C2 using extracting and cutting agent A2 Replace C1, thus obtaining drilling fluid Y2, its density is 1.1g/cm³.

Embodiment 3

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent C3 using extracting and cutting agent A3 Replace C1, thus obtaining drilling fluid Y3, its density is 1.1g/cm³.

Embodiment 4

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1,0.2 weight portion using extracting and cutting agent A4 Coating agent C4 replace C1, thus obtaining drilling fluid Y4, its density be 1.1g/cm³.

Embodiment 5

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent C5 using extracting and cutting agent A5 Replace C1, thus obtaining drilling fluid Y5, its density is 1.1g/cm³.

Comparative example 1

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent using extracting and cutting agent DA1 DC1 replaces C1, thus obtaining drilling fluid DY1, its density is 1.1g/cm³.

Comparative example 2

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent using extracting and cutting agent DA2 DC2 replaces C1, thus obtaining drilling fluid DY2, its density is 1.1g/cm³.

Comparative example 3

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, replaces A1, coating agent using extracting and cutting agent DA2 DC3 replaces C1, thus obtaining drilling fluid DY3, its density is 1.1g/cm³.

Comparative example 4

Water-based drilling formula of liquid according to embodiment 1, except for the difference that, using modified starch (purchased from Shandong get Shun Yuan The LYS of Petroleum Technology Co., Ltd) replace fluid loss additive N1, chemical industry (is tieed up purchased from Renqiu section using partially hydrolyzed polyacrylamide (PHPA) The A1225 of company) replace extracting and cutting agent A1, coating agent is replaced using polyacrylic acid potassium (purchased from HNQ of Hebei Yan Xing chemical company) C1, thus obtaining drilling fluid DY4, its density is 1.1g/cm³.

Test case 1

The rheological property of above drilling fluid, filtration property and surface tension are measured, specifically measures above-mentioned drilling well Liquid apparent viscosity (AV) before ageing, plastic viscosity (PV), yield value (YP), ratio of dynamic shear force/yield value to plastic viscosity, gel initial, 10-minute gel strength, middle press filtration Vector (API) and surface tension, the results are shown in Table shown in 1, wherein：

Apparent viscosity (AV) is using the fast viscosimeter of normal form six side according to specified in standard GB/T/T29170-2012 Method measures, and unit is mPa s,

Plastic viscosity (PV) is using the fast viscosimeter of normal form six side according to specified in standard GB/T/T29170-2012 Method measures, and unit is mPa s, PV=θ₆₀₀-θ₃₀₀.

Yield value (YP) is using the fast viscosimeter method according to specified in standard GB/T/T29170-2012 of normal form six Measure, YP=0.511 × (2 × φ 300- φ 600), unit is Pa.

Gel initial calculates by the following method：Stir 10s under the speed of 600r/min, after standing 10s, read the maximum of φ 3 Then full-scale reading is obtained gel initial divided by 2 by reading, and unit is Pa.

10-minute gel strength calculates by the following method：Stir 10s under the speed of 600r/min, after standing 10min, read φ 3 Then full-scale reading is obtained 10-minute gel strength divided by 2 by big reading, and unit is Pa.

Ratio of dynamic shear force/yield value to plastic viscosity is calculated as follows：

API refers to middle press filtration vector, is to commit a breach of etiquette using middle press filtration to be surveyed according to the method in SY/T 5621-93 standard Amount, unit is mL.

Surface tension refers to drilling fluid, and it is to adopt Contact-angle measurement according to the method in GB/T22237-2008 standard Instrument, selects sessile drop method to record.

Table 1

Excellent rheological property is had by the drilling fluid that the data of table 1 can be seen that the present invention, there is relatively low viscosity With higher yield value, gel strength, more than 0.30 ratio of dynamic shear force/yield value to plastic viscosity can be maintained, the coal petrography that carries and suspend that can be good simultaneously Bits；The drilling fluid of the present invention has relatively low filter loss, can greatly reduce in drilling fluid Free water to the leakage in coal seam；This Outward, the drilling fluid of the present invention has low surface tension, can be effectively prevented from the generation of the water lock phenomenon that capillary force leads to, thus Keep the intact of coal-bed methane seepage passage, there is good reservoir protection performance.

Test case 2

The residue rate of above-mentioned drilling fluid is measured, the results are shown in Table shown in 2, detailed process includes：Take the above-mentioned brill of 300mL Well liquid, adds the gel breaker potassium peroxydisulfate of 0.05 weight %, is placed in standing 4h at 90 DEG C after stirring evenly, and fully breaks glue；Take certain body The above-mentioned drilling fluid after breaking gel of long-pending V is put in centrifuge, is centrifuged 30min under 10000rpm rotating speed, adds after pouring out supernatant Enter distilled water and be centrifuged 30min again under the rotating speed of 10000rpm；Pour out and dry at 90 DEG C after supernatant, and after measuring drying Quality m of the remaining residue of above-mentioned drilling fluid, is calculated as follows residue rate：Residue rate=m/V, unit is mg/L.

Table 2

Can be seen that in addition to comparative example DY4 by the data of table 2, all test drilling fluids be respectively provided with 35mg/L with Under residue rate, illustrate that gel breaker can sufficiently act on the compositions of additives of the present invention, and can effectively make inorganic agent Lost efficacy or degraded, level of residue was extremely low.This performance is beneficial to the anti-row's operation after coal bed gas well finishing drilling, and low residue rate ensure that brill The Low Damage to reservoir for the well liquid inorganic agent, illustrates that the drilling fluid of the present invention is very suitable for the drillng operation of coal bed gas well.

The preferred embodiment of the present invention described in detail above, but, the present invention is not limited in above-mentioned embodiment Detail, in the range of the technology design of the present invention, multiple simple variant can be carried out to technical scheme, this A little simple variant belong to protection scope of the present invention.

It is further to note that each particular technique feature described in above-mentioned specific embodiment, in not lance In the case of shield, can be combined by any suitable means, in order to avoid unnecessary repetition, the present invention to various can The combination of energy no longer separately illustrates.

Additionally, can also be combined between the various different embodiment of the present invention, as long as it is without prejudice to this The thought of invention, it equally should be considered as content disclosed in this invention.

Claims

1. a kind of drilling fluid additive composition being applied to coal bed gas well is it is characterised in that said composition contains thickening carries and cutting Agent, coating agent and fluid loss additive, wherein：

Described thickening extracting and cutting agent is containing shown in the construction unit shown in the construction unit shown in formula (1), formula (2) and formula (3) The copolymer of construction unit, wherein：

Formula (1)Formula (2)

Formula (3)

Wherein, R¹、R^1'、R²、R^2'、R⁵、R^5'、R⁴With each R⁷It is each independently selected from the alkyl of H and C1-C8；R³、R⁶And R⁸Each Alkylidene independently selected from C0-C8；X is selected from-NH- or-O-；N is the integer of 1-4；

Described coating agent is combed polysaccharide compound, the change shown in lower formula (I) of the side chain of described combed polysaccharide compound Compound shown in compound and formula (II) provides, and wherein, described sulfonate polysaccharide class compound is the starch of sulfonation, the fiber of sulfonation Chlorins compound or the xanthans of sulfonation：

Formula (I)Formula (II)

Described fluid loss additive is nano-crystal cellulose.

2. composition according to claim 1, wherein, the weight ratio of described thickening extracting and cutting agent, coating agent and fluid loss additive For 100：5-50：100-300, preferably 100：6-30：120-200, more preferably 100：7-25：150-180.

3. composition according to claim 1 and 2, wherein, in the copolymer as described thickening extracting and cutting agent, R¹、R^1'、R²、 R^2'、R⁵、R^5'、R⁴With each R⁷It is each independently selected from the alkyl of H and C1-C6；R³、R⁶And R⁸It is each independently selected from C0-C6's Alkylidene；N is the integer of 1-3；

Preferably, R¹、R^1'、R²、R^2'、R⁵、R^5'And R⁴It is each independently selected from the alkyl of H and C1-C4；Each R⁷Independently of one another Alkyl selected from C1-C6；R³Alkylidene selected from C0-C4；R⁶And R⁸It is each independently selected from the alkylidene of C1-C6；

It is highly preferred that R¹、R^1'、R²、R^2'、R⁵、R^5'And R⁴It is each independently selected from H, methyl, ethyl, n-propyl, isopropyl and just Butyl；Each R⁷It is each independently selected from methyl, ethyl, n-propyl, isopropyl and normal-butyl；R³Selected from C0 alkylidene ,- CH₂-、-CH₂-CH₂-、-CH₂-CH₂-CH₂-、-CH(CH₃)-CH₂-、-CH₂-CH(CH₃)-or-CH₂-(CH₂)₂-CH₂-；R⁶And R⁸ It is each independently selected from-CH₂-、-CH₂-CH₂-、-CH₂-CH₂-CH₂-、-CH(CH₃)-CH₂-、-CH₂-CH(CH₃)-、-CH₂- (CH₂)₂-CH₂-、-CH₂-CH(CH₃)-CH₂-、-C(CH₃)₂-CH₂-、-CH₂-C(CH₃)₂-、-CH₂-(CH₂)₃-CH₂- and-CH₂- (CH₂)₄-CH₂-.

4. the composition according to any one in claim 1-3, wherein, as the copolymer of described thickening extracting and cutting agent In, the mol ratio of the construction unit shown in the construction unit shown in formula (1), formula (2) and the construction unit shown in formula (3) is 10- 40：1-10：1, preferably 15-30：2-5：1；

Preferably, the weight average molecular weight of described copolymer is 1,000,000-6,000,000g/mol, preferably 2,000,000- 5,500,000g/mol, more preferably 2,500,000-5,000,000g/mol, still more preferably for 3,000,000-4, 500,000g/mol.

5. the composition according to any one in claim 1-4, wherein, as the described copolymer viscosifying extracting and cutting agent Preparation method includes：

In aqueous solvent, in the presence of radical initiator and chain-transferring agent, by the (1') shown compound of formula, formula (2') institute The compound showing and the (3') shown compound of formula carry out Raolical polymerizable, wherein,

Formula is (1')Formula is (2')

Formula is (3')

Preferably, the (2') shown compound of the (1') shown compound of formula, formula and the (3') shown compound of formula mole with Amount ratio is 10-40：1-10：1, preferably 15-30：2-5：1；

Preferably, the (2') shown compound of the (1') shown compound of the formula with respect to 1mol, formula and the (3') shown change of formula Mole total amount of compound, the consumption of described aqueous solvent is 400-1000mL, preferably 400-600mL；

Preferably, described radical initiator is 4,4'- azo (4- cyanopentanoic acid), azo diisobutyl amidine hydrochloride, azo One or more of diisopropyl imidazoline hydrochloride and azo diisobutyl imidazoline hydrochloride；

Preferably, the (2') shown compound of the (1') shown compound of the formula with respect to 1mol, formula and the (3') shown change of formula Mole total amount of compound, the consumption of described radical initiator is 0.1-0.2mmol, preferably 0.11-0.14mmol；

Preferably, described chain-transferring agent is selected from one or more of sodium formate, sodium acetate, ammonium hydroxide and urea；

Preferably, the (2') shown compound of the (1') shown compound of the formula with respect to 1mol, formula and the (3') shown change of formula Mole total amount of compound, the consumption of described chain-transferring agent is 0.1-0.2mmol, preferably 0.13-0.15mmol.

6. composition according to claim 5, wherein, in the preparation method as the copolymer of described thickening extracting and cutting agent, The condition of Raolical polymerizable includes：Temperature is 40-80 DEG C, and the time is 6-12h；

Preferably, the condition of Raolical polymerizable includes：Temperature is 50-70 DEG C, and the time is 7-10h；

Preferably, this Raolical polymerizable is carried out also in the presence of chelating agent, described chelating agent be selected from ethylenediamine tetra-acetic acid and Its salt, nitrilotriacetic acid and its salt, hexa metaphosphoric acid and its one or more of salt and diethylenetriamine penta；

Preferably, the (2') shown compound of the (1') shown compound of the formula with respect to 1mol, formula and the (3') shown change of formula Mole total amount of compound, the consumption of described chelating agent is 0.01-0.05mmol, preferably 0.01-0.02mmol；

Preferably, the method includes：First will be (3') shown to compound (2') shown to the (1') shown compound of formula, formula, formula Compound and aqueous solvent are mixed, and are re-introduced into described radical initiator, chain-transferring agent and optional chelating agent, and lazy Carry out described Raolical polymerizable under property atmosphere.

7. composition according to claim 1 and 2, wherein, as in the combed polysaccharide compound of described coating agent, L¹、 L^1'、L²And L^2'It is each independently selected from H, methyl, ethyl, n-propyl, isopropyl and normal-butyl；

Preferably, the weight average molecular weight of described combed polysaccharide compound is 9,000,000-15,000,000g/mol, preferably 9,500,000-14,500,000g/mol, more preferably 10,000,000-13,500,000g/mol；

Preferably, the content of the construction unit of the compound shown in formula (I) and the offer of the compound shown in formula (II) is 80-95 Weight %, preferably 85-92 weight %；

Preferably, the mol ratio of the construction unit of the compound shown in formula (I) and the offer of the compound shown in formula (II) is 1： 0.2-1, preferably 1：0.2-0.5, more preferably 1：0.24-0.4；

Preferably, the cellulose compound of described sulfonation is the carboxymethylcellulose calcium of sulfonation, the hydroxymethyl cellulose of sulfonation, sulphur The carboxyethyl cellulose of change, the hydroxypropyl methyl fiber of the hydroxyethyl cellulose of sulfonation, the hydroxypropyl cellulose of sulfonation or sulfonation Element.

8. the composition according to claim 1 or 7, wherein, as the system of the combed polysaccharide compound of described coating agent Preparation Method includes：

(1) in aqueous solvent, polysaccharide compound and sulfonating agent are carried out sulfonating reaction, obtains sulfonate polysaccharide class compound；

(2) in aqueous solvent, in the presence of graft copolymerization catalyst, by the chemical combination shown in sulfonate polysaccharide class compound, formula (I) Compound shown in thing and formula (II) carries out graft copolymerization；

Formula (I)Formula (II)

Preferably, described cellulose compound is carboxymethylcellulose calcium, hydroxymethyl cellulose, carboxyethyl cellulose, ethoxy One or more of cellulose, hydroxypropyl cellulose and hydroxypropyl methyl cellulose；

Preferably, described sulfonating agent is one or more of chlorosulfonic acid, sulfur trioxide, PS and concentrated sulfuric acid；

Preferably, with respect to the described polysaccharide compound of 100 weight portions, the consumption of described sulfonating agent is 20-40 weight portion, excellent Elect 25-35 weight portion as；

Preferably, in step (1), with respect to the described polysaccharide compound of 100 weight portions, the consumption of aqueous solvent is 1000- 5000 weight portions, preferably 2000-4000 weight portion；

Preferably, the condition of described sulfonating reaction includes：Temperature is 50-70 DEG C, preferably 55-65 DEG C；Time is 8-20h, excellent Elect 10-12h as.

9. composition according to claim 8, wherein, with respect to the described sulfonate polysaccharide class compound of 100 weight portions, formula (I) total consumption of the compound shown in and the compound shown in formula (II) is 500-1500 weight portion, preferably 800-1000 weight Amount part, more preferably 850-950 weight portion；

Preferably, the mol ratio of the compound shown in formula (I) and the consumption of compound shown in formula (II) is 1：0.2-1, preferably For 1：0.2-0.5, more preferably 1：0.24-0.4；

Preferably, described graft copolymerization catalyst is one or more of high-valency metal compound and persulfate, more preferably Ground, described high-valency metal compound is ammonium ceric nitrate, ferric trichloride, in four (4- carboxyl phenyl) Cob altporphyrin and vanadium acetylacetonate One or more；Described persulfate is one or more of ammonium persulfate, sodium peroxydisulfate and potassium peroxydisulfate；

Preferably, with respect to the described sulfonate polysaccharide class compound of 100 weight portions, the consumption of described graft copolymerization catalyst is 0.1-2 weight portion, preferably 0.2-1 weight portion, more preferably 0.2-0.5 weight portion；

Preferably, in step (2), with respect to the described sulfonate polysaccharide class compound of 100 weight portions, the consumption of aqueous solvent is 5000-10000 weight portion, preferably 6000-9000 weight portion；

Preferably, in step (2), the condition of described graft copolymerization includes：Temperature is 10-40 DEG C for temperature, preferably 20- 35℃；Time is 10-30h, preferably 16-25h.

10. composition according to claim 1 and 2, wherein, the average grain diameter of described nano-crystal cellulose is 100-600nm, It is preferably 150-320nm；

Preferably, described nano-crystal cellulose is bar-shaped.

In 11. claims 1-10, the composition described in any one is as the application of the additive in drilling fluid.

A kind of 12. water-base drilling fluids containing the composition described in any one in claim 1-10.

13. water-base drilling fluids according to claim 12, wherein, with respect to the water in the water-base drilling fluid of 100 weight portions, The content of described composition is 3-10 weight portion, preferably 4-8 weight portion.

14. water-base drilling fluids according to claim 12 or 13, wherein, described water-base drilling fluid is salt-water drilling fluid, phase For the water in the water-base drilling fluid of 100 weight portions, the content as the salt of heavy weight additive is 5-10 weight portion.

Application in coal bed gas well drilling well for the water-base drilling fluid described in any one in 15. claims 12-14.