CN114835449B - Early strength cement paste system suitable for frozen soil layer well cementation - Google Patents

Early strength cement paste system suitable for frozen soil layer well cementation Download PDF

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CN114835449B
CN114835449B CN202210337099.9A CN202210337099A CN114835449B CN 114835449 B CN114835449 B CN 114835449B CN 202210337099 A CN202210337099 A CN 202210337099A CN 114835449 B CN114835449 B CN 114835449B
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CN114835449A (en
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叶雨明
汪振海
李泽林
李勋
商尧
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Puyang Minghua Chemical Co ltd
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
    • C04B28/04Portland cements
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00724Uses not provided for elsewhere in C04B2111/00 in mining operations, e.g. for backfilling; in making tunnels or galleries
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20Mortars, concrete or artificial stone characterised by specific physical values for the density
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00Technologies for solid waste management
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Abstract

The invention belongs to the technical field of oil and gas field development, and particularly relates to an early strength cement paste system suitable for frozen soil layer well cementation, which comprises the following raw materials in parts by weight: 100 parts of G-grade or C-grade oil well cement meeting the GB10238 standard requirements, 1-5 parts of low-temperature early strength agent, 1-3 parts of low-temperature fluid loss agent, 1-4 parts of low-temperature coagulant, 0.2-2.5 parts of microcrystalline expansion agent, 0.5-5 parts of low-temperature cementing activator and 0.1-0.6 part of defoaming agent. The invention can greatly shorten the thickening time of the cement paste, the thickening time is easy to adjust, the initial consistency is moderate, and the on-site slurry preparation and injection replacement are facilitated; the formed cement stone has micro-expansibility; the slurry has good stability, easy water loss control and quick development of a gel structure, can realize the requirement of short coagulation, has higher early strength and stable later strength, and ensures that the sealing quality of the ultralow temperature oil and gas well and the requirement of long-term development are met. The invention also discloses the composition of the important material in the cement paste system, the preparation process of the product and the application method of the material.

Description

Early strength cement paste system suitable for frozen soil layer well cementation
Technical Field
The invention relates to the technical field of oil and gas field development, in particular to an early strength cement paste system suitable for cementing frozen soil layers.
Background
Both high and cold frozen soil layer well cementation and deep water low temperature well cementation have the problems of low cement slurry hydration speed, long waiting setting time, shallow oil-gas water channeling, easy collapse of soft stratum and the like under low temperature and ultralow temperature conditions. At present, the research on the well cementation cement slurry at the ultralow temperature in China is rarely reported, and the foreign methods mainly comprise a high-aluminum cement slurry system, a cement slurry system of G-grade cement and superfine cement and a cement slurry and coagulant system of G-grade cement, wherein the high-aluminum cement slurry has the problem of serious decline of later strength although the strength development is fast at the low temperature, the G-grade cement and superfine cement slurry system has the problems of high slurry consistency, poor channeling-preventing performance and difficult pumping in field construction, and the G-grade cement and coagulant system usually has the problems that the cement slurry cannot be well thickened and the time can not be shortened under the ultralow temperature condition, the setting time is long, the hydration heat release of the cement slurry is obvious, and the channeling-preventing performance is poor.
Disclosure of Invention
The invention aims to solve the problem of long waiting time of cement paste at ultralow temperature in the prior art, and provides an early strength cement paste system suitable for frozen soil layer well cementation.
In order to achieve the purpose, the invention adopts the following technical scheme:
an early strength cement paste system suitable for frozen soil layer well cementation comprises the following raw materials in parts by weight: 100 parts of G-grade or C-grade oil well cement meeting the GB10238 standard requirements, 1-5 parts of low-temperature early strength agent, 1-3 parts of low-temperature fluid loss agent, 1-4 parts of low-temperature coagulant, 0.2-2.5 parts of microcrystalline expansion agent, 0.5-5 parts of low-temperature cementing activator, 0.1-0.6 part of defoaming agent, 44 parts of water for G-grade cement and 56 parts of water for C-grade cement.
Preferably, the G-grade oil well cement is G-grade high-sulfate-resistance oil well cement meeting the GB10238 standard requirement, and the components comprise 60-65% of tricalcium silicate, 14-19% of dicalcium silicate, 1.0-2.0% of tricalcium aluminate, 10-15% of tetracalcium aluminoferrite, 0.5-2.0% of sulfur trioxide, 0.5-5.0% of magnesium oxide and 300m of fineness 2 /kg-400m 2 The C-grade oil well cement is C-grade high-sulfate-resistance oil well cement meeting the GB10238 standard requirement, the content of tricalcium silicate in the components is 60-75%, the content of dicalcium silicate is 13-16%, the content of tricalcium aluminate is 1.5-3.0%, the content of magnesium oxide is 3.0-5.0%, the content of sulfur trioxide is 2.5-3.0%, and the fineness is 440m 2 /kg~500m 2 /kg。
Preferably, the low-temperature early strength agent comprises the following main components: the calcium formate/aluminum sulfate composite material comprises calcium formate, calcium sulphoaluminate, nano metal silicon, sodium metaaluminate, formamide and modified calcium oxide, and the mass percentages of the components are as follows: 12 to 20 percent of calcium formate, 12 to 18 percent of calcium sulphoaluminate, 12 to 15 percent of formamide, 10 to 15 percent of nano-metal silicon, and trace sodium metaaluminate and modified calcium oxide. The preparation process of the low-temperature early strength agent comprises the following steps: putting calcium formate, calcium sulphoaluminate and nano-metal silicon into a drum-type stirrer, adding modified calcium oxide through a small-size charging opening during stirring, mixing for 1h, preparing sodium metaaluminate solution with proper concentration and formamide solution with proper concentration, spraying and stirring in sequence, drying at low temperature for 1-2 days by proper process, sieving, grinding, mixing and stirring for 30min.
Preferably, the low-temperature coagulant mainly comprises the following components: the slow-release agent comprises the following components in percentage by mass: 10-16% of aluminum sulfate, 12-16% of basic alumina, 10-12% of potassium sulfate, 8-12% of potassium chloride, 6-10% of sodium fluosilicate, triethanolamine, triisopropanolamine and slow release agent. The preparation process of the low-temperature coagulant comprises the following steps: mixing and stirring aluminum sulfate, basic aluminum oxide, potassium sulfate and potassium chloride, and preparing triethanolamine, triisopropanolamine and a slow-release agent into a mixed solution with a proper concentration, wherein the mass ratio of the triethanolamine to the triisopropanolamine to the slow-release agent is 2.5:1.5: and 6, atomizing and mixing the solid powder with the mixed solution for 10min in the stirring process, drying at a low temperature for 1-2 days by using a proper process, sieving, grinding, mixing and stirring for 30min.
Preferably, the low-temperature cementing activator comprises the following main components: the slag material comprises superfine slag microcrystal, anhydrous sodium aluminate, aluminum sulfate, modified calcium sulfate whisker, magnesium oxide, kaolin and ammonium persulfate, wherein the mass percentages of the components are as follows: 25-35% of superfine slag microcrystalline core, 18-25% of modified calcium sulfate whisker, 12-25% of ammonium persulfate, 8-15% of kaolin, and trace anhydrous sodium aluminate and magnesium oxide. The preparation process of the low-temperature cementing activator comprises the following steps: firstly, superfine slag microcrystal is prepared, and slaked lime, slag powder and superfine quartz powder are mixed according to the proportion of 1.5-2.0: 5.0 to 7.0:1.5 to 2.0, placing the mixture into an autoclave, controlling the pressure to be 0.7MPa and the temperature to be 70 ℃, keeping the temperature for 6 hours, fully stirring the mixture, then placing the mixture into a rotary oven for dehydration at 105 ℃ as fast as possible after pressure relief, cooling and fully grinding the mixture to ensure that the specific surface area of the mixture is 500m 2 /kg~560m 2 Forming superfine slag microcrystal core; superfine slag microcrystal, aluminum sulfate, modified calcium sulfate whisker, anhydrous sodium aluminate, magnesium oxide, kaolin and ammonium persulfate are mixed according to a certain proportion and fully and uniformly mixed.
Preferably, the microcrystalline expansion agent comprises the following main components: sodium aluminate, potassium nitrate, calcium sulphoaluminate, sodium thiosulfate, superfine mica, polyacrylamide and carboxymethyl cellulose, wherein the mass percent of each component is as follows: 18 to 22 percent of potassium nitrate, 18 to 22 percent of sodium aluminate, 10 to 15 percent of sodium thiosulfate, 12 to 18 percent of superfine mica, 8 to 12 percent of calcium sulphoaluminate, and trace amounts of polyacrylamide and carboxymethyl cellulose. The preparation process of the microcrystalline expanding agent comprises the following steps: mixing potassium nitrate, sodium aluminate, superfine mica and calcium sulphoaluminate, fully stirring, preparing sodium thiosulfate solution with proper concentration, atomizing, stirring, drying at 50 ℃, grinding for one day, adding polyacrylamide and carboxymethyl cellulose, mixing and stirring for 1h to obtain the finished product.
Preferably, the low-temperature fluid loss agent suitable for the frozen soil layer can be composed of one or more composite materials such as polyvinyl alcohol, polyacrylamide, carboxymethyl cellulose and the like, is not limited to the fluid loss agent produced by the company, and has the compatibility requirement: (1) no retardation effect, (2) no obvious influence on the slurry consistency, (3) no adverse influence on the cement stone strength;
preferably, the ratio of the early strength of the low-temperature early strength agent is more than or equal to 1.35, the ratio of the strength in 24 hours is more than or equal to 1.2, the ratio of the thickening time is less than or equal to 1.0, the initial consistency is less than or equal to 30Bc, and the free liquid is less than or equal to 0.5%.
Preferably, the ratio of the compressive strength of the low-temperature coagulant is more than or equal to 1.2, the ratio of the thickening time is less than or equal to 0.5, the free liquid is less than or equal to 1.0 percent, and the initial consistency is less than or equal to 30Bc.
Preferably, the water loss amount of the low-temperature fluid loss agent is less than or equal to 50mL, the time of 40 Bc-100 Bc is less than or equal to 30min, the initial consistency is less than or equal to 30Bc, and the free liquid is less than or equal to 1.4%.
The microcrystalline expansion agent has a relative expansion rate of 0.4-3.2% in 48h, a thickening time variation value of +/-30 min, a thickening linear deformation value of less than or equal to 10Bc and a transition time of less than or equal to 40min.
Preferably, the ratio of the 24h strength of the low-temperature cementing activator is more than or equal to 1.2, the initial consistency is less than or equal to 30Bc, and the thickening linear deformation value is less than or equal to 5Bc.
Compared with the prior art, the invention has the beneficial effects that:
the invention can greatly shorten the thickening time of the cement paste, the thickening time is easy to adjust, the initial consistency is moderate, the in-situ slurry preparation and injection replacement are facilitated, and the rapid sealing of an oil-gas layer is facilitated.
The invention can realize the requirement of short-term curing, the development speed of the gel strength is high, and the strength can reach 14MPa at 0 ℃ for 48 hours; the strength of 48h at the temperature of minus 4 ℃ can reach 10MPa, and the formed cement has micro expansibility, compact and tough cement, higher early strength and stable later strength, and ensures the long-acting sealing quality of the ultralow temperature oil gas water layer and the long-term development requirement.
The invention has the advantages of easy water loss control, good slurry stability and fast gel structure development speed, can better control oil gas water channeling and ensure the well cementation quality.
Drawings
FIG. 1 is a graph showing the relationship between the amount of coagulant added in an early strength cement slurry system suitable for cementing in frozen soil layers;
FIG. 2 is a graph showing the relationship between the amount of the early strength agent in the early strength cement paste system suitable for cementing in the frozen soil layer;
FIG. 3 is a graph showing the relationship between the amount of the low-temperature gelling activator in the early strength cement slurry system suitable for cementing in the frozen soil layer;
FIG. 4 is a Qishen 1 well surface layer cementing sound amplitude diagram;
FIG. 5 is a 15 ℃ thickening curve for an early strength cement slurry system suitable for permafrost cementing;
FIG. 6 is a 4 ℃ thickening curve for an early strength cement slurry system suitable for permafrost cementing;
FIG. 7 is a 0 ℃ thickening curve for an early strength cement slurry system suitable for permafrost cementing.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Before the test, the cement, the admixture and the stirring equipment are pre-cooled to-7 ℃, and the mixing water is pre-cooled to 1 ℃. The preparation and testing of the cement slurry was carried out according to SY/T19139 oil well cement test method, the temperature of the cement slurry was recorded immediately after mixing, and the temperature was measured and recorded for all tests.
Example one
The invention provides an early strength cement slurry system suitable for frozen soil layer well cementation, which comprises the following raw materials in parts by weight: 100 parts of Jiahua G-grade oil well cement, 2.5 parts of low-temperature early strength agent, 3 parts of low-temperature fluid loss agent, 3 parts of low-temperature coagulant, 2 parts of microcrystalline expansion agent and 2 parts of low-temperature cementing activator; 0.2 part of defoaming agent; and 44 parts of water. In the embodiment, the low-temperature early strength agent, the low-temperature cementing activator, the low-temperature coagulant, the low-temperature fluid loss agent and the microcrystalline expanding agent are all products of the company I.
Example two
The embodiment is an early strength cement slurry system suitable for frozen soil layer well cementation, which comprises the following raw materials in parts by weight: 100 parts of Tianshan C-grade oil well cement, 2 parts of a low-temperature early strength agent, 3 parts of a low-temperature fluid loss agent, 3 parts of a low-temperature coagulant, 1.5 parts of a microcrystalline expansion agent and 2 parts of a low-temperature cementing activator; 0.2 part of defoaming agent; and 56 parts of water. In the embodiment, the low-temperature early strength agent, the low-temperature cementing activator, the low-temperature coagulant, the low-temperature fluid loss agent and the microcrystalline expanding agent are all products of the company I.
Comparative example 1
100 parts of G-grade oil well cement and 44 parts of water.
Comparative example 2
The common formula of the low-temperature ultralow-temperature well in the Qinghai oilfield comprises the following components: 100 parts of G-grade oil well cement, 2.0 parts of early strength agent (Euramerican gram), 3 parts of low-temperature fluid loss additive (Minghua chemical industry), 3.0 parts of low-temperature coagulant (Medium oil Bohai star), 2 parts of expanding agent (Wei Hui chemical industry), 0.2 part of defoaming agent (Wei Hui chemical industry), 44 parts of water and 1.90G/cm cement paste density 3
The test data for comparative examples 1 and 2 and examples 1 and 2 are shown in the following table:
Figure BDA0003577019260000061
Figure BDA0003577019260000071
and (3) displaying a detection result: the invention can greatly shorten the thickening time of the cement paste, the thickening time is easy to adjust, the initial consistency is moderate, the on-site slurry preparation and injection replacement are facilitated, and the quick oil-gas layer sealing is facilitated; the requirement of short curing can be realized, the strength can reach 8MPa at 0 ℃ for 24h and can reach 14MPa for 48h; the strength can reach 10MPa at the temperature of minus 4 ℃ for 48 hours. The formed cement stone has micro-expansibility, compact and tough cement stone, higher early strength and stable later strength, and ensures the long-acting sealing quality of the ultralow temperature oil gas water layer and the long-term development requirement. The invention can control the water loss within 50mL, has good slurry stability and fast gel structure development speed, and can better control the oil gas water channeling.
The low-temperature early strength agent applied in the embodiment is an important technical measure for improving the early strength stability and the later strength of the cement paste for cementing in the frozen soil layer, and comprises the following main components: calcium formate, calcium sulphoaluminate, nano-metal silicon, sodium metaaluminate, formamide and modified calcium oxide;
the low-temperature coagulant applied in the embodiment effectively shortens the thickening time of cement paste for cementing in a frozen soil layer, accelerates the setting speed of the cement paste, and is beneficial to improving the early strength of cement stones, and the low-temperature coagulant mainly comprises the following components: aluminum sulfate, basic aluminum oxide, potassium sulfate, potassium chloride, sodium fluosilicate, triethanolamine, triisopropanolamine and the like;
the low-temperature cementing activator applied in the embodiment is an important technical measure for ensuring the hydration activity of the cement slurry for cementing the frozen soil layer under the conditions of low temperature and ultralow temperature, and comprises the following main components: superfine slag microcrystal, anhydrous sodium aluminate, aluminum sulfate, modified calcium sulfate whisker, magnesium oxide, kaolin and ammonium persulfate.
The low-temperature expanding agent applied in the embodiment comprises the following main components: sodium aluminate, potassium nitrate, calcium sulphoaluminate, sodium thiosulfate, superfine mica, polyacrylamide and carboxymethyl cellulose;
the low-temperature fluid loss agent applied in the embodiment comprises the following main components: the low-temperature fluid loss agent has good fluid loss performance at low temperature, has no influence on the consistency of slurry, has no delayed coagulation phenomenon, is beneficial to improving the strength of cement stone, has good compatibility with other additives, and can also be used as other low-temperature fluid loss agents with similar performance in the market.
In the examples:
the technical requirements of cement slurry for ensuring the cementing quality of the frozen soil layer are as follows: 1. the thickening time of the cement paste meets the requirement of short waiting set; 2. the compression strength of the set cement is improved; 3. the hydration activity of the cement paste under the ultralow temperature condition is better; 4. micro-expansibility of set cement.
1. Control of thickening time
Thickening time control in this technique is dominated by low temperature set accelerator adjustment, the dosage regime of which is shown in FIG. 1.
The formula is as follows: jiahua grade G cement, low-temperature early strength agent 1.0% + low-temperature coagulant adjustment + H 2 O44%
The low temperature setting accelerators have a good linear relationship, the thickening time is easily adjustable and the amount added varies with the base formulation.
2. Early strength enhancement of set cement
The improvement of the strength of the cement stone in the technology mainly takes the adjustment of the low-temperature early strength agent as a main part, the early strength performance of the low-temperature early strength agent is obviously improved along with the increase of the addition amount, and the addition amount relationship is shown in figure 2;
the formula is as follows: jiahua grade G cement + activator 0.5% + low-temperature early strength agent adjustment + H 2 O44%
The early strength is obviously improved along with the increase of the addition of the early strength agent, and the early strength agent is also suitable for low-density cement slurry. When the low-temperature early strength agent, the low-temperature cementing activator and the high-strength cement are matched in application, a more optimized effect can be achieved.
3. Improvement of hydration activity of cement paste under ultralow temperature condition
The low-temperature cementing activator in the technology is an important technical measure for ensuring the hydration activity of the cement slurry for cementing the frozen soil layer under the conditions of low temperature and ultralow temperature, and the dosage relationship in the application is shown in figure 3.
The formula is as follows: JHG + low temperature coagulant 1.0% + low temperature activator adjustment + H 2 O 44%
The low-temperature cementing activator can not only improve the hydration activity of cement paste under the ultralow temperature condition, but also excite the activity of an admixture in the cement paste in low-density cement paste, and improve the compression strength of set cement.
4. Control of the micro-expansion properties of set cement
In the technique, the micro-expansibility of the cement stone is mainly adjusted by a microcrystal expansion agent, the relative expansion rate is properly controlled within the range of 0.5-3.5%, and the addition amount of the microcrystal expansion agent can be controlled within the range of 0.5-3.0%.
An example of creating a record in this patent application is described below
Qi Can 1 well- - -well with highest world altitude (altitude 4100m, frozen soil layer 680 m) is characterized in that the lowest air temperature of a south qijun block is-31.3 ℃, the highest temperature is 20 ℃, the temperature is below 0 ℃ all year night, the frozen soil layer of the qishen 1 well in the block reaches 680m, the frozen soil layer contains abundant underground ice, the stratum is extremely sensitive to the temperature, if the temperature is increased in the cement paste injection and replacement process, the ice and soil dissolution speed is high, the stratum can collapse the well wall, the construction risk is high, the environmental pollution is serious, and the prevention means of complex accidents are few. When the temperature is lower than 0 ℃, the water in the cement paste is condensed into ice and does not participate in cement hydration, so that the cement paste is not solidified and has no strength.
Qi Can 1 well skins and techniques require permafrost seal. Through a comparison test of months, the well is determined to adopt a frozen soil layer well cementation cement slurry system of our company, the system has certain thixotropy, the strength, thickening time and other properties meet the requirements of the frozen soil layer well cementation, and the cement slurry properties are shown in the following table
Figure BDA0003577019260000101
Experimental data can show that the thickening time and the setting time of the cement paste can be obviously shortened under the ultralow-temperature condition, the thickening time is easy to adjust, the slurry consistency is moderate, and the construction safety and stability are high; the slurry has small filtration loss, fast development speed of slurry gel strength and good channeling-preventing performance; the formed cement stone has micro-expansibility, higher early strength, good interface cementation quality and good evaluation of logging sound amplitude.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (5)

1. An early strength cement slurry system suitable for cementing frozen soil layers is characterized by comprising the following raw materials in parts by weight: 100 parts of G-grade or C-grade oil well cement meeting the GB10238 standard requirements, 1-5 parts of low-temperature early strength agent, 1-3 parts of low-temperature fluid loss agent, 1-4 parts of low-temperature coagulant, 0.2-2.5 parts of microcrystalline expansion agent, 0.5-5 parts of low-temperature cementing activator, 0.1-0.6 part of defoaming agent, 44 parts of water for G-grade cement and 56 parts of water for C-grade cement;
the G-grade oil well cement meets the GB10238 standard requirements, and comprises 60-65% of tricalcium silicate, 14-19% of dicalcium silicate, 1.0-2.0% of tricalcium aluminate, 10-15% of tetracalcium aluminoferrite, 0.5-2.0% of sulfur trioxide, 0.5-5.0% of magnesium oxide and 300m of fineness 2 /kg~400m 2 The C-grade oil well cement is C-grade high-sulfate-resistance oil well cement meeting the GB10238 standard requirement, and the components of the C-grade oil well cement comprise 60-75% of tricalcium silicate, 13-16% of dicalcium silicate, 1.5-3.0% of tricalcium aluminate, 3.0-5.0% of magnesium oxide, 2.5-3.0% of sulfur trioxide and 440m of fineness 2 /kg~500m 2 /kg;
The low-temperature early strength agent comprises the following main components: the calcium formate/aluminum sulfate composite material comprises calcium formate, calcium sulphoaluminate, nano metal silicon, sodium metaaluminate, formamide and modified calcium oxide, and the mass percentages of the components are as follows: 12-20% of calcium formate, 12-18% of calcium sulphoaluminate, 12-15% of formamide, 10-15% of nano-metal silicon, trace sodium metaaluminate and modified calcium oxide, and the preparation process of the low-temperature early strength agent comprises the following steps: placing calcium formate, calcium sulphoaluminate and nano-metal silicon in a drum-type stirrer, adding modified calcium oxide through a small-size charging opening during stirring, mixing for 1h, preparing a sodium metaaluminate solution with a proper concentration and a formamide solution with a proper concentration, sequentially spraying and stirring, drying at a low temperature for 1-2 days by a proper process, sieving, grinding, mixing and stirring for 30min;
the low-temperature coagulant comprises the following main components: the aluminum sulfate, basic aluminum oxide, potassium sulfate, potassium chloride, sodium fluosilicate, triethanolamine and triisopropanolamine, and the mass percentages of the components are as follows: 10-16% of aluminum sulfate, 12-16% of basic alumina, 10-12% of potassium sulfate, 8-12% of potassium chloride, 6-10% of sodium fluosilicate, triethanolamine, triisopropanolamine and slow release agent are all trace;
the preparation process of the low-temperature coagulant comprises the following steps: mixing and stirring aluminum sulfate, basic alumina, potassium sulfate, potassium chloride and sodium fluosilicate, preparing mixed solution with proper concentration by triethanolamine, triisopropanolamine and sustained-release agent, wherein the mass ratio of the triethanolamine to the triisopropanolamine to the sustained-release agent is 2.5:1.5:6, atomizing and mixing the solid powder with the mixed solution for 10min in the stirring process, drying at low temperature for 1-2 days by a proper process, sieving, grinding, mixing and stirring for 30min;
the low-temperature cementing activator comprises the following main components: the slag material comprises superfine slag microcrystal, anhydrous sodium aluminate, aluminum sulfate, modified calcium sulfate whisker, magnesium oxide, kaolin and ammonium persulfate, wherein the mass percentages of the components are as follows: 25-35% of superfine slag microcrystalline core, 18-25% of modified calcium sulfate whisker, 12-25% of ammonium persulfate, 8-15% of kaolin, and trace anhydrous sodium aluminate and magnesium oxide;
the preparation process of the low-temperature cementing activator comprises the following steps: firstly, superfine slag microcrystal is prepared, and slaked lime, slag powder and superfine quartz powder are mixed according to the weight ratio of 1.5-2.0: 5.0-7.0: 1.5 to 2.0, placing the mixture into an autoclave, controlling the pressure to be 0.7MPa and the temperature to be 70 ℃, keeping the temperature for 6 hours, fully stirring the mixture, then placing the mixture into a rotary oven for dehydration at 105 ℃ as fast as possible after pressure relief, cooling and fully grinding the mixture to ensure that the specific surface area of the mixture is 500m 2 /kg~560m 2 Forming superfine slag microcrystal core; mixing and fully and uniformly mixing superfine slag microcrystal, aluminum sulfate, modified calcium sulfate whisker, anhydrous sodium aluminate, magnesium oxide, kaolin and ammonium persulfate;
the microcrystalline expanding agent comprises the following main components: sodium aluminate, potassium nitrate, calcium sulphoaluminate, sodium thiosulfate, superfine mica, polyacrylamide and carboxymethyl cellulose, wherein the mass percent of each component is as follows: 18 to 22 percent of potassium nitrate, 18 to 22 percent of sodium aluminate, 10 to 15 percent of sodium thiosulfate, 12 to 18 percent of superfine mica, 8 to 12 percent of calcium sulphoaluminate, and trace amounts of polyacrylamide and carboxymethyl cellulose;
the preparation process of the microcrystalline expanding agent comprises the following steps: mixing potassium nitrate, sodium aluminate, superfine mica and calcium sulphoaluminate, fully stirring, preparing a sodium thiosulfate solution with proper concentration, atomizing, stirring, drying, crushing and grinding at low temperature by a proper process, adding polyacrylamide and carboxymethyl cellulose, mixing and stirring for 1h to obtain a finished product;
the low-temperature fluid loss agent suitable for the frozen soil layer well cementation can be composed of one or more composite materials such as polyvinyl alcohol, polyacrylamide and carboxymethyl cellulose, is not limited to the fluid loss agent produced by the company, and has the compatibility requirement: no delayed coagulation effect, no obvious influence on the slurry consistency and no adverse effect on the cement stone strength.
2. The early strength cement slurry system suitable for cementing frozen soil layers according to claim 1, wherein the ratio of the early strength of the low-temperature early strength agent is more than or equal to 1.35, the ratio of the strength of 24h is more than or equal to 1.2, the ratio of the thickening time is less than or equal to 1.0, the initial consistency is less than or equal to 30Bc, and the free liquid is less than or equal to 0.5%.
3. The early strength cement slurry system suitable for cementing frozen soil layers according to claim 1, wherein the low temperature coagulant has a compressive strength ratio of not less than 1.2, a thickening time ratio of not more than 0.5, a free fluid of not more than 1.0% and an initial consistency of not more than 30Bc.
4. The early strength cement paste system suitable for frozen soil layer cementing according to claim 1, wherein the low temperature fluid loss agent has a water loss of less than or equal to 50mL, a time of 40Bc to 100Bc of less than or equal to 30min, an initial consistency of less than or equal to 30Bc, a free liquid of less than or equal to 1.4%, the microcrystalline swelling agent has a 48h relative expansion rate of 0.4-3.2%, a thickening time variation value of +/-30 min, a thickening linear mutation value of less than or equal to 10Bc, and a transition time of less than or equal to 40min.
5. The early strength cement slurry system suitable for permafrost cementing according to claim 1, wherein the ratio of the 24h strength of the low temperature cementing activator is not less than 1.2, the initial consistency is not more than 30Bc, and the thickening linear deformation value is not more than 5Bc.
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