176results about How to "Improve breaking performance" patented technology

The invention discloses a zinc-alloy zipper tooth belt produced by a row microphone method, in particular to zinc alloy for a zipper tooth belt and a preparation method of the zipper tooth belt. The alloy comprises the following components by weight percent: 0.5-5% of Cu, 10-4.5% of Al, 0.01-0.2% of Mg and the balance of X, Y, Zn and unavoidable impurities, wherein the sum of the percentages of the components is 100%; the X is selected from at least one of 0.0001-0.5% of Bi, 0.01-0.19% of Ti, 0.001-0.3% of RE, 0.001-1% of Ni and 0.001-1% of Si; and Y is selected from at least one of Mn, Co, Nb, Zr, Cr, Ca, P, Sb, Te and Se. By adopting the deformed zinc alloy and the alloy producing method disclosed in the invention, the production of the zipper line can be met, and the zipper tooth belt can be produced smoothly by the row microphone method; and the produced zipper can be processed into different colors.

The invention provides an acrylamide polymer thickener and a preparation method thereof, and a fracturing fluid, wherein the acrylamide polymer thickener is composed of the components by the mass percentage: 20%-45% of a hydrophilic propenyl monomer, 4%-6% of a hydrophobic propenyl monomer, 1%-2% of an emulsifier, 0.2%-0.5% of an initiator, a latent crosslinking agent and the balance water, wherein the latent crosslinking agent accounts for 0.5%-1.8% of the total mass of the hydrophilic propenyl monomer and the hydrophobic propenyl monomer; the acrylamide polymer thickener provided by the invention solves the technical problems in the prior art that a polymer thickener has poor temperature resistance and salt tolerance and poor shearing stability, and the prepared acrylamide polymer thickener has high-temperature performance, and can effectively meet the requirements of on-site construction of slick water fracturing.

Disclosed is a nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, a nonaqueous electrolyte solution, and a porous insulating membrane bonded to the surface of at least one of the positive electrode and the negative electrode. The porous insulating membrane contains an inorganic oxide filler and a membrane binder. The ratio (R) of the true volume of the separator to the apparent volume is not less than 0.4 but not more than 0.7, and the ratio (R) and the porosity (P) of the porous insulating membrane satisfy the following relation: -0.10 <= R - P <= 0.30.

The invention relates to a rubber crusher and a rubber crushing method. The rubber crusher comprises a rack, a rubber crushing chamber supported by the rack, a discharge hopper positioned at the bottom of the rubber crushing chamber, and a roller device and a rubber cutter group which are arranged in the rubber crushing chamber, wherein the roller device is arranged at the top of the rubber crushing chamber, and comprises two rollers which are matched with each other; the rubber cutter group is arranged on the middle lower part of the rubber crushing chamber, and comprises a moving cutter and a fixed cutter which are matched with each other. The rubber crusher and the rubber crushing method have the beneficial effects that rubber blocks can be primarily rolled to form slices in advance, the slices are cut, and a separant is simultaneously sprayed to prevent the crushed rubber from being adhered; the advantages of an open mill and a rubber crusher are integrated, and the good rubber crushing effect and the high rubber crushing efficiency are ensured.

The invention provides a preparation method of a graphite-based double-gate MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), belonging to the fields of microelectronics and solid electronics. The preparation method comprises the following steps: forming a high-quality SiO2 layer on a monocrystalline silicon substrate; coating a layer of high polymer in a spinning way on the SiO2 layer, wherein the high polymer is used as a carbon source for preparing graphite; depositing a catalytic metal layer on the high polymer and performing high temperature annealing so at to form graphite at the junction face of the SiO2 layer and the catalytic metal layer; windowing the catalytic metal layer and forming a source and a drain of the transistor by using photolithography and an etching process; depositing a layer of high-K film in the windowed area by using an atomic deposition system and preparing a front metal gate above the high-K film; and finally preparing a back metal gate on the back of the Si substrate to obtain a double-gate MOSFET device based on a graphite trench material and a high-K gate dielectric medium.

The invention discloses a seawater-based fracturing fluid for fracturing a sea high-temperature oil-gas reservoir and relates to the technical field of cross-linked gel fracturing fluid. The seawater-based fracturing fluid comprises a base solution, a cross-linking agent and a thickening agent, wherein the base solution comprises the components (in percentage by weight) in terms of the weight of the prepared seawater-based fracturing fluid total solution as follows: 0.3%-0.8% of thickening agent, 0.1%-0.3% of pH regulating agent, 0.1%-0.5% of discharge aiding agent and the balance being seawater; relative to the mass fraction of the base solution, the cross-linking agent is 0.4%-0.6%; and the thickening agent refers to guar gum, carboxy-methyl hydroxypropyl guar gum, hydroxypropyl guar gum, fenugreek gum or sesbania gum. The seawater-based fracturing fluid is adopted, so that the dissolving speed of the thickening agent is quick, and therefore, direct mixing and continuous constructing can be realized, and therefore, the seawater-based fracturing fluid is in particular suitable for the fracturing construction of the sea high-temperature oil-gas reservoir. Meanwhile, the fracturing fluid can be continuously sheared for 90 minutes under the conditions of 150 DEG C and 170s<-1>, so that the viscosity is kept to be 70mPa.s or more.

Low-molecular-weight polymer fracturing liquid is mainly applied to fracturing modification of low-infiltration alkali-sensitive reservoirs and water injection wells and consists of, in weight percentage, 0.25-0.6% of XT-3 low-molecular-weight polymer densifier, 0.2-0.6% of crosslinking agent, 0.5-2% of potassium chloride, 0.02-0.08% of crosslinking modifier, 0.2-0.5% of cleanup additive, 0.0001-0.15% of ammonium persulfate and the balance of water. The low-molecular-weight polymer fracturing liquid is prepared by adding clean water into a liquid preparation tank firstly, adding acetic acid during stirring, then adding the XT-3 low-molecular-weight polymer densifier, the potassium chloride and the cleanup additive after uniformly stirring, stirring more than 10 minutes after materials are added until density or viscosity of upper liquid and lower liquid in the liquid preparation tank are uniform, and finally, adding the crosslinking agent and adhesive breaker according to requirements during fracturing. The low-molecular-weight polymer fracturing liquid has the advantages that residues of the fracturing liquid and alkali-sensitive damages of the reservoirs are solved, the fracturing liquid is prepared and used conveniently, temperature resistance and shearing resistance are fine, and the requirements of fracturing modification of low infiltration and alkali-sensitive reservoirs can be met.

The invention relates to steel for a Ca microalloying free-cutting high-strength expansion-breaking connecting rod. The steel is prepared from, by mass percent, 0.25%-0.60% of C, 0.10%-1.20% of Si, 0.40%-1.50% of Mn, 0.05%-0.50% of Cr, 0.02%-0.15% of S, 0.02%-0.15% of P, 0.03%-0.55% of V, 0.0005%-0.0080% of Ca, 0.002%-0.035% of N, 0.002%-0.080% of Al, not larger than 0.02% of Ti and the balance Fe and inevitable impurity elements. The steel is subjected to smelting, continuous casting, heating, hot rolling and cooling, and the structure characteristic is uniform ferrite and pearlite. According to the steel, key elements in the steel are optimized, Ca microalloying is especially adopted, and the steel for the expansion-breaking connecting rod with high strength, good cutting machinability, good expansion-breaking performance and excellent comprehensive performance is obtained, and the design requirements for engine light weight, economical efficiency and driving comfort are met.

The invention relates to a carboxymethyl hydroxypropyl guanidine gum fracturing fluid which is used for fracturing reformation of a high-temperature and low-permeability reservoir. The carboxymethyl hydroxypropyl guanidine gum fracturing fluid comprises the components by weight percent: 0.25-0.6% of carboxymethyl hydroxypropyl guanidine gum, 0.2-0.6% of cross-linking agent, 0.2-0.4% of cross-linking regulator, 0.5-1% of clay stabilizer, 0.05-0.1% of bactericidal preservative, 0.2-0.5% of discharge aiding agent, 0.0001-0.15% of ammonium persulfate and the balance of water. A preparation method of the fracturing fluid comprises the steps of: adding clear water into a large tank, adding the carboxymethyl hydroxypropyl guanidine gum into the large tank under the stirring condition, and then sequentially adding the clay stabilizer, the discharge aiding agent, the cross-linking regulator and the bactericidal preservative into the large tank; and stirring for 10 minutes until the concentration or the viscosity of liquid at the upper part and the lower part of the large tank is uniform and consistent. During fracturing construction, the cross-linking agent and gel breaker are added into the large tank according to the requirement. The carboxymethyl hydroxypropyl guanidine gum fracturing fluid has the effects of being suitable for the reservoir temperature of 80-200DEG C, reducing the residue of the fracturing fluid and the construction friction, and meeting the demand of fracturing reformation of the high-temperature and low-permeability reservoir.

The invention discloses a medium carbon non-hardened and tempered steel for a fractured connecting rod, which belongs to the field of alloy steel. The medium carbon non-hardened and tempered steel comprises the following chemical components in percentage by weight: 0.35 to 0.55 percent of C, 0.40 to 0.80 percent of Si, 0.80 to 1.50 percent of Mn, 0.04 to 0.15 percent of P, 0.03 to 0.10 percent of S, 0.10 to 0.50 percent of Cr, 0.05 to 0.25 percent of V, 0.0005 to 0.006 percent of B, 0.01 to 0.10 percent of Ti, 0.005 to 0.05 percent of Al, 0.005 to 0.020 percent of N, 0.005 to 0.04 percent of RE and the balance of Fe and other inevitable impurities. Meanwhile, the C content, P content and B content are required to meet a brittleness parameter relationship: the sum of C(percent),P(percent) and 50B(percent) is more than or equal to 0.06 and less than or equal to 1.0. A metallographic structure is composed of ferrite and pearlite. The medium carbon non-hardened and tempered steel is suitable for manufacturing fractured connecting rods with a tensile strength of more than 900MPa. Compared with the prior art, the invention has the advantages that: the steel has low plasticity and high fracturing performance and fatigue performance; and the steel can be used to manufacture fractured connecting rods after being forged and processed and has high economy.

The invention discloses a high temperature-resistant acidic cross-linked polymer thickening agent and a preparation method and application thereof, which belongs to the technical field of fracturing fluids used for oil field reservoir reconstruction. The thickening agent is a straight-chain low-molecular polymer which is formed by copolymerization of four monomers consisting of acrylic acid, acrylamide, 2-acrylamido-methylpropanesulfonate and p-alkenyl benzene sulfonate and is cross-linkable under an acidic condition; the thickening agent has the advantages of high sand-carrying performance, shearing resistance, easy dissolving, no pollution and little damage to a reservoir; since the thickening agent has a benzene ring structure, the thickening agent has high temperature resistance and is applicable to fracturing of high-temperature and strong base-sensitive strata. The preparation method for the high temperature-resistant acidic cross-linked low-molecular thickening agent is simple, has low cost and is applicable to large-scale production and application. A gel breaking system prepared from the thickening agent is jelly-like, does not suffer from precipitation and separation, has good compatibility and excellent sand-carrying performance and gel breaking performance and poses less damage to the reservoir.

The invention relates to a fracturing fluid which comprises a base fluid A and a base fluid B, wherein the base fluid A is prepared from a thickening agent, a hydrotropy thickening agent, a clay stabilizer, a discharge aiding agent, a sterilizing agent, a demulsifying agent, a low-temperature activator and water; the base fluid B is prepared from a low-molecular weight polymer, the clay stabilizer, the discharge aiding agent, the sterilizing agent, the demulsifying agent, the low-temperature activator and the water. When fracturing construction is carried out, the base fluid A and the base fluid B are mixed in proportion, the low-molecular weight polymer and a thickening agent molecule are mutually wound in a stirring process to form a certain space reticular structure for effective thickening, and the hydrotropy thickening agent compresses a winding structure through electric repulsion so that a gel is further thickened and forms good solid carrying capacity; the shearing is carried out at 50 DEG C and 170S-1,3.5MPa for 60 minutes, the viscosity is more than 50 mPa.s, an oxidized type gel breaker is added according to the proportion of 0.01%-0.20% in a wedge shape, the gel can be thoroughly broken within 2 hours, and the viscosity of gel breaking liquid is less than 5 mPa.s.

The invention provides high-temperature-resistant ground cross-linked acid liquor. The acid liquor comprises the following components in percentage by mass: 15-28 weight percent of acid, 0.4-1.0 weight percent of polyacrylamide polymer, 0.1-0.5 weight percent of aldehyde cross-linking agent, 0.05-0.25 weight percent of phenol cross-linking agent, 0.05-0.02 weight percent of crosslinking promoter, 0.5-2.0 weight percent of corrosion inhibitor, 0.5-2.0 weight percent of ferric ion stabilizer, 0.01-0.1 weight percent of ammonium persulfate and the balance of water, wherein the acid is calculated based on pure substances. The invention also provides a method for preparing the high-temperature-resistant ground cross-linked acid liquor. Industrial raw materials which are low in toxicity and low in price are taken as cross-linking agents and cross-linking promoter, the toxicity of the cross-linking agents can be reduced, the process for preparing the high-temperature-resistant ground cross-linked acid liquor is simple, further synthesis is not needed, the field operability is high, the cost is effectively reduced, and application of acid fracturing is further widened.

A deep compaction gas-pool pressure-crack liquid is composed : thickener 0.2-1.0%, surfactant 0.05-0.2%, clay stabilizer 0.1-1%, germicide0.01-0.2%, buffering agent 0.05-0.2%, the temperature stabilizer 0.1-0.5%, the high temperature cross linker 0.1-0.5%, the cross linking control agent 0.1-0.5%, the broker gum agent 0.001-0.01%, the broken gum catalyst 0.0001-0.001%, the antifoam agent 0.01-0.1%, the falling filter-lossing agent 1-5%, water: the rest. The liquid is of thermal resistance and shearing performance and It can decrease the nowel of the pressure-crack liquid and the filting loss, also it can improve efficiency.

The invention provides steel for an automobile engine connecting rod as well as a manufacturing method thereof. The steel for the connecting rod comprises the following components in percentage by weight: 0.32 to 0.40 percent of C, 0.40 to 0.70 percent of Si, 0.80 to 0.95 percent of Mn, 0.025 to 0.040 percent of S, 0.030 to 0.045 percent of P, 0.10 to 0.25 percent of Cr, less than 0.10 percent ofMo, 0.08 to 0.20 percent of Nb, 0.015 to 0.035 percent of Ti, less than or equal to 0.10 percent of Ni, 0.012 to 0.020 percent of N, less than or equal to 15*10<-6> of O and the balance of Fe and unavoidable impurities. The manufacturing method comprises the steps of performing converter smelting, performing external refining, performing continuous casting, performing casting blank slow cooling aswell as heating and rolling. The steel for the connecting rod as well as the manufacturing method thereof can guarantee that the tensile strength is more than 1000 MPa, the yield strength is more than 700 MPa and sulfide inclusion is controlled to be within level 3.0; and the steel for the connecting steel has the characteristics of high processing property, high breaking property and long life.

The invention relates to a high-temperature water base fracturing fluid and a preparation method thereof. The fracturing fluid is prepared from the following additives by weight: 0.45-1.0% of a thickening agent, 0.6-1.5% of a clay stabilizer, 0.6-1.5% of an emulsion breaking cleanup additive, 0.01-0.03% of a gel breaking agent, 0.6-2.0% of a crosslinking agent and the balance of sea water, wherein the total sum weight percentages of the components is 100%. The fracturing fluid has the advantages of good sand carrying capability, good heat resistant and shearing resistant performances, good compatibility with formation fluid and small reservoir damage; seawater can be used directly to prepare the solution; and conventional liquid dispensing equipment and process are employed to solve the problem of lack of freshwater in offshore fracturing construction. The invention improves working efficiency of offshore fracturing, reduces the cost, and lays the foundation for the large-scale offshore fracturing operation.

The invention discloses super a guanidine gum fracturing fluid, which is used for the fracturing modification of a high-temperature and low-permeability water-sensitive storage layer. The super guanidine gum fracturing fluid comprises the following components in percentage by weight: 0.25-0.6% of super guanidine gum, 0.5-2% of potassium chloride, 0.5-1.0% of organic clay stabilizing agent, 0.05-0.1% of JA-1 sterilizing preservative, 0.2-0.5% of non-ionic discharge aiding agent, 0.1-0.2% of crosslinking regulator, 0.0001-0.15% of ammonium persulfate, 0.2-0.6% of organic boron and zirconium compound crosslinking agent and the balance of water. The super guanidine gum is added into clear water ,followed by circulating for 15 minutes at a big displacement; and then, the potassium chloride, the organic clay stabilizing agent, the discharge aiding agent, sodium thiosulfate, triethanolamine, the crosslinking regulator and sterilizing preservative are successively added to cause the concentration or the viscosity of liquid to be consistent. During the fracturing construction, the crosslinking agent and the ammonium persulfate are added. The super guanidine gum fracturing fluid has the effects that a super guanidine gum fracturing fluid series formula suitable for the temperature of the reservoir stratum is formed, the residues of the fracturing fluid are reduced, and the modification requirement on the high-temperature and low-permeability water-sensitive storage layer can be satisfied.

The invention relates to ultra low temperature super guanidine gum fracturing fluid, comprising the ingredients with mass percents as follows: 0.20% of super guanidine gum, 0.12% of organopolysiloxane, 0.07% of polyoxypropylene polyoxyethylene polyoxypropylene octadeyl alcohol ether, 0.32% of cationic organic amino, 0.09% of cationic long chain polymer, 0.03% of organic silicone oil, 0.0003% of borax, 0.00027% of persulfate, 0.00009% of hyper-valent oxysalt, 0.00014% of peroxide and balance of water. The fracturing fluid has good anti-shearing property and breaks gum completely.

The invention discloses an organic aluminum-zirconium crosslinking agent and a preparation method thereof, and a low-molecular polymer fracturing fluid. The crosslinking agent is prepared by reacting the following raw materials in parts by weight: 15-25 parts of zirconium salt, 15-25 parts of aluminum salt, 150-250 parts of polyalcohol, 75-85 parts of organic acid, 15-25 parts of gluconate and 55-65 parts of water. The organic aluminum-zirconium crosslinking agent has excellent high temperature resistance, and has favorable crosslinking effect under the conditions of high temperature and high salinity. The organic aluminum-zirconium crosslinking agent is stable under the condition of low pH value, can implement acid crosslinking, and ensures the normal proceeding of the acid fracturing. The organic aluminum-zirconium crosslinking agent has favorable compatibility with polymers and high crosslinking capacity; and the fracturing fluid formed by compounding the organic aluminum-zirconium crosslinking agent with polymers has the advantages of stable gel, excellent solid carrying capacity, excellent viscosity breaking performance and excellent shearing resistance under high-temperature conditions. The organic aluminum-zirconium crosslinking agent has the characteristics of high solubility, no pollution and low damage degree to the reservoir, and has wide application prospects.

The invention discloses polymer gel for well killing and a preparing method and application of the polymer gel. The polymer gel for well killing is composed of partially hydrolyzed polyacrylamide, chromium acetate, thiourea, a structure reinforcing agent and water, wherein the polymer gel for well killing comprises, by mass, 1%-4% of the partially hydrolyzed polyacrylamide, 0.1%-0.4% of the chromium acetate, 0.05%-0.2% of the thiourea, 1%-7% of the structure reinforcing agent and the balance water. The structure reinforcing agent is Na-montmorillonite or corn starch or organic montmorillonite. The polymer gel for well killing is high in pressure resisting strength, has good adhesion force and a good sealing effect on a casing pipe and can be applied to under-balanced well completion of an oil deposit or a gas deposit.

The invention relates to a low concentration guanidine gum fracturing fluid for gas well. The fracturing fluid is composed of hydroxypropyl guar gum, an anti-swelling stabilizer, a bactericide, a foaming cleanup additive, a conditioning agent, a temperature stabilizing agent, a chelating agent, a crosslinking agent, a gel breaker, and water. The provided fracturing fluid overcomes the shortages of a conventional fracturing fluid for gas well such as a large using amount of thickening agent, a large amount of residues after gel breaking, and the like. The preparation cost is low. The performance on resisting temperature and shearing is good. The using concentration of guanidine gum is greatly reduced. The damage on stratum is obviously reduced. Prominent economic benefit is created, and the application prospect is wide.

The invention provides a composition for preparing a fracturing thickening agent, the fracturing thickening agent and a preparation method of the fracturing thickening agent, and belongs to the technical field of polymerization water-soluble polymer petroleum auxiliaries. The composition comprises a water phase, an oil phase and a reverse phase agent, the water phase comprises a nonionic monomer, a salt-resistant monomer, a hydrophobic monomer, a rigid monomer, a cross-linking agent, an initiator and water; the oil phase comprises white oil and an emulsifying agent. A nonionic monomer, a salt-resistant monomer, a hydrophobic monomer, a rigid monomer, a cross-linking agent and other components are dissolved in water to serve as the water phase, white oil and the emulsifying agent are emulsified to serve as the oil phase, all the components are matched with one another under a reasonable proportion to play a synergistic role, an inverse emulsion copolymerization reaction is carried out, the prepared fracturing thickening agent has remarkable salt resistance and temperature resistance and good viscoelasticity.

The invention discloses an underground coal mine hydraulic sand fracturing system and method. The underground coal mine hydraulic sand fracturing system comprises a water supply system, a fluid distribution system, a sand mixing system, a fracturing system and a high-pressure manifold system; the fracturing system is formed by two fracturing pump groups in parallel; the high-pressure manifold system comprises a Y-shaped tee, and two inlet channels of the Y-shaped tee separately communicate with outlets of the two fracturing pump groups; and the fluid distribution system comprises two fluid distribution pools. The fracturing method is implemented based on the fracturing system and comprises the steps that fracturing liquid is prepared by densifiers, crosslinking agents, anti-swelling agents, gel breakers and water according to proportion; the particle size of a supporting agent is 40-70 meshes, and the volume density of ceramsite sand is 1.25g / cm<3>; and fracturing is carried out according to the sequence of first hydraulic fracturing seam generating and later fracturing liquid sand-carrying fracturing support. The underground coal mine hydraulic sand fracturing system has the beneficial effects that the fracturing system is simple in structure and reasonable in layout, and is suitable for sand-carrying fracturing use of underground narrow and small or long and narrow space; andthe fracturing liquid prepared by the fracturing method has suspended sand characteristic, can be suitable for upward drilling sand-carrying fracturing, and has the environmental protection characteristic of being capable of directly discharged.

The invention discloses starch / nanometer SiO2 composite gel, and a preparation method and application thereof. The starch / nanometer SiO2 composite gel is prepared from the following ingredients in percentage by mass through being metered by the mass of the composite gel: 1 to 4 mass percent of partially hydrolyzed polyacrylamide, 0.1 to 0.4 mass percent of chromium acetate (cross linking agents), 0.05 to 0.2 mass percent of thiourea, 0.5 to 5 mass percent of nanometer SiO2, 0.5 to 7 mass percent of corn starch and the balance water. The composite gel provided by the invention has the advantages that the pressure-resistant intensity and the viscoelasticity are high; the excellent adhesive force and sealing effects are achieved on a sleeve; and the starch / nanometer SiO2 composite gel is particularly applicable to medium-low-temperature oil-gas reservoirs.

The invention provides non-quenched and non-tempered steel, a production method of the non-quenched and non-tempered steel and a cracking connecting rod manufactured through the non-quenched and non-tempered steel. The non-quenched and non-tempered steel is prepared from, by mass percent, 0.46%-0.52% of C, 0.70%-0.80% of Si, 1.53%-1.60% of Mn, 0.008%-0.015% of P, 0.02%-0.035% of S, 0.15%-0.25% of Cr, 0.20%-0.25% of Ni, 0.04%-0.07% of Mo, 0.02%-0.04% of Al, 0.14%-0.16% of V, 0.025%-0.035% of Nb, 0.001%-0.002% of B, 0.14%-0.25% of N and the balance Fe and inevitable impurity elements. The fatigue toughness of the steel can be improved through the element Nb. The element B can be segregated in a grain boundary and fused in ferrite separated out of the grain boundary, the separated-out ferrite is strengthened, and the cracking performance is improved.

The invention relates to the technical field of fracturing and production increasing of an oil well or natural gas well, and in particular relates to a low damage carboxymethyl hydroxypropyl guanidine gum foam fracturing fluid of a low permeability gas reservoir and a preparation method of the low damage carboxymethyl hydroxypropyl guanidine gum foam fracturing fluid. The low damage carboxymethyl hydroxypropyl guanidine gum foam fracturing fluid of the low permeability gas reservoir contains the following components in parts by weight: 100 parts of base solution, 0.2-0.5 part of cross-linking agent, 0.03-0.04 part of gel breaker, and liquid nitrogen, wherein the liquid nitrogen accounts for 5-7 percent of total volume of the base solution and the cross-linking agent. The base solution, the cross-linking agent and a gel breaker are pumped into an underground fracturing stratum, and the liquid nitrogen is pumped, the base solution, the cross-linking agent, the gel breaker and the liquid nitrogen are mixed uniformly on the underground fracturing stratum, thus the low damage carboxymethyl hydroxypropyl guanidine gum foam fracturing fluid reaches the purpose of fracturing operation, and has the advantages of low content of residue after fracturing, good gel breaking property, rapid flowback, little damage to reservoir stratum water, and good fracturing effect. According to the low damage carboxymethyl hydroxypropyl guanidine gum foam fracturing fluid, the production cost is lowered, and the working efficiency is increased.

The invention discloses a high-temperature guanidine gum cross-linking agent and a preparation method thereof. A preparation process of the guanidine gum cross-linking agent includes steps: preparing an organic boron cross-linking agent and an organic zirconium cross-linking agent, and well mixing according to a volume ratio of 0.15-0.2:1 to obtain an organic boron-zirconium cross-linking agent. The guanidine gum cross-linking agent is excellent in temperature resistance and shear resistance, gum viscosity measured by a HAAKE rheometer is still kept to be 100mPa.s or above after shearing of a cross-linking system for 2h at 180 DEG C and 170s<-1>, and ultrahigh-temperature-resistant guanidine gum cross-linking agent BZC and GHPG cross-linked gel is excellent in temperature resistance and shear resistance; the researched organic boron-zirconium cross-linking agent is capable of retarding cross linking for 1-4min; the cross-linking agent is excellent in gel breaking performance, short in gel breaking time and low in gel breaking liquid residue quantity and surface tension.