Foaming composition for cement and foamed cement containing foaming composition

Abstract

The invention provides a foaming composition for cement and foamed cement containing the foaming composition. Foamed cement containing the foaming composition for cement is used as hot dry rock heat preservation well cementation cement, heat loss can be effectively reduced, the requirements for stability, toughness and corrosion resistance under the high-temperature condition can be met, and good application prospects are achieved.

Description

Technical Field

[0001] This invention belongs to the field of hot dry rock insulation and cementing technology, and particularly relates to a foaming composition for cement and foamed cement containing the same. Background Technology

[0002] Hot dry rock is a new type of renewable geothermal energy with the following three advantages: (1) Hot dry rock has abundant energy storage, stable heat supply, high utilization efficiency, and long service life; (2) The heat medium stays underground for a short time during the heat extraction process, and will not dissolve a large amount of minerals; (3) Hot dry rock power generation system is a closed loop, which will not produce pollution and is low-carbon and environmentally friendly.

[0003] Currently, the main method for utilizing hot dry rock is through enhanced geothermal systems (EGS). This involves creating artificial fractures within the hot dry rock using "high-pressure injection" to form a heat convection channel between the fluid and the hot dry rock. Water / CO2 is typically used as the heat exchange medium and injected into the artificially fractured rock fracture zone through deep wells. The heated rock is then heated through contact with the high-temperature rock mass before being returned to the surface for geothermal power generation.

[0004] During the flow of fluid within the wellbore, a temperature difference exists between the fluid and the formation at the same depth. Heat is continuously transferred between the hot water and the formation through the wellbore, which consists of cement and casing, thus affecting the hot water outlet temperature and geothermal energy utilization efficiency. Currently, double-layer casing filled with insulating material or insulating coatings applied to the inner wall of the casing are commonly used to reduce heat transfer efficiency within the casing. While these methods offer some insulation, their cost remains high. In contrast, the thermal conductivity of the cement system is easily adjustable, its cost is relatively low, and it is highly operable, offering broad application prospects and significant economic and social benefits.

[0005] Therefore, it is of great significance to develop a dry hot rock insulation cementing system that can effectively reduce heat loss and meet the requirements of stability, toughness and corrosion resistance under high temperature conditions. Summary of the Invention

[0006] To address the problem of low geothermal energy utilization efficiency caused by the easy loss of heat from the fluid inside the wellbore during the extraction and utilization of hot dry rock geothermal energy in existing technologies, the present invention aims to provide a cement system for hot dry rock well insulation that has good heat preservation effect, maintains good stability, toughness and corrosion resistance under high temperature conditions, and is coated on the inner wall of the wellbore to reduce heat loss during the extraction of hot dry rock geothermal energy and improve geothermal energy utilization efficiency.

[0007] To achieve the above objectives, one aspect of the present invention provides a foaming composition for cement, comprising an N-fatty acyl amino acid type foaming agent, sodium higher fatty acid, water glass, and an air-entraining agent.

[0008] According to the present invention, the mass of the foaming composition for cement is 100%, wherein the mass of the N-fatty acyl amino acid type foaming agent is 4.5wt%-5.5wt%, the mass of the sodium higher fatty acid is 9wt%-11.1wt%, the mass of the water glass is 51wt%-53.5wt%, and the mass of the air-entraining agent is 32wt%-33.5wt%.

[0009] According to the present invention, the N-fatty acyl amino acid type foaming agent is sodium N-fatty acyl amino acid.

[0010] According to the present invention, the N-fatty acyl amino acid sodium comprises at least one of sodium stearoyl lysine, sodium linoleyl glycinate, and sodium oleoyl glutamate.

[0011] According to the present invention, the higher sodium fatty acid comprises at least one of C14 to C18 sodium fatty acids.

[0012] According to the present invention, the modulus of the water glass is 2.7-3.4; and / or the Baume degree is 48°-52°.

[0013] According to the present invention, the air-entraining agent is a rosin-based air-entraining agent.

[0014] According to the present invention, the foaming composition for cement is used to produce a stepped-pore foam structure.

[0015] The second invention provides a foamed cement, the raw materials of which include cement base material, cement foaming composition, stabilizer and waterproofing agent;

[0016] The foaming composition for cement is one of the foaming compositions for cement described in this invention.

[0017] According to the present invention, the total mass of the raw materials of the foamed cement is 100 parts by mass, and the foamed cement includes 55-89 parts by mass of the cement base, 5-28.4 parts by mass of the foaming composition for cement, 2.8-10 parts by mass of the stabilizer and 3-7 parts by mass of the waterproofing agent.

[0018] According to the present invention, the C2S content in the cementitious material is not less than 45 wt%; and / or the molar ratio of calcium oxide to silicon oxide is in the range of (1.85-2.15):1; and / or

[0019] The 7-day heat of hydration of the cementitious material is not higher than 220 kJ / kg.

[0020] According to the present invention, the stabilizer is waste concrete; and / or

[0021] The SiO2 content in the waste concrete is not less than 70 wt%; and / or

[0022] The fineness of the waste concrete powder is not less than 320 mesh.

[0023] According to the present invention, the foamed cement stone prepared from the foamed cement has a stepped pore foam structure.

[0024] According to the present invention, the total pore volume of the stepped pore foam structure is taken as 100%, pores with a diameter of 70-200μm account for 2.5%-3.8% of the total pore volume, pores with a diameter of 680-1300μm account for 15%-23% of the total pore volume, and pores with a diameter of 2-4mm account for the remaining percentage of the total pore volume.

[0025] Application of the foamed cement composition provided by one of the present inventions or the foamed cement provided by another of the present invention in hot dry rock insulation cementing.

[0026] Advantages of the invention

[0027] In view of the problem that the utilization efficiency of geothermal energy is low due to the easy loss of heat from the fluid in the wellbore during the extraction and utilization of hot dry rock geothermal energy in the existing technology, the present invention provides a foaming composition for cement and foamed cement containing the same.

[0028] Compared with the prior art, the present invention has at least the following advantages:

[0029] (1) In the foaming composition for cement provided by the present invention, the N-fatty acyl amino acid foaming agent is combined with sodium fatty acid to form a bubble group with a three-level stepped diameter distribution in the foamed cement slurry. The addition of rosin-type air-entraining agent can work with the N-fatty acyl amino acid foaming agent and sodium fatty acid to adjust the surface tension of the solution and maintain the stability of the bubble group. This allows the stepped pore foam structure to be maintained during the curing process of the foamed cement slurry until the formation of foamed cement stone. This can enhance the stability of the foamed cement slurry and also help to enhance the corrosion resistance, strength and toughness of the foamed cement stone.

[0030] (2) During the curing process of foam cement slurry made of foam cement, the stepped pore foam structure is combined with the combination of "giant silicate particles + silicates" provided by waste concrete and cement base material. The combination of "giant silicate particles + silicates" provided by waste concrete and cement base material is filled into the thin wall of larger diameter air bubbles to form a foam cement structure. The cement is maintained on the foam wall with a smaller diameter under the action of foam surface tension, forming a foam cement stone with a stepped pore foam structure.

[0031] (3) The foamed cement slurry made from the foamed cement provided by this invention has an excellent and stable foam structure, which is convenient for construction. The key technical parameters of the foamed cement stone formed by its curing are as follows: the average compressive strength after curing for 2 days, 7 days, and 14 days is 10 MPa, 11.7 MPa, and 14.2 MPa, respectively; the average density after curing for 14 days is 1 g / cm³. 3 The average elastic modulus is 2.8 GPa, the average thermal conductivity is approximately 0.23 W / m·K, and the average coefficient of thermal expansion is 7°C. -6 / ℃; Foamed cement stone samples cured for 14 days were placed in an environment of "20% H2S + 15% CO2" and aged at 85℃ for 7 days. The average compressive strength was 7.8 MPa and the average permeability was 0.0074 mD. It can be seen that the foamed cement stone formed by the curing of foamed cement slurry prepared by the foaming composition for cement provided by the present invention has high compressive strength, low density and elastic modulus, low thermal conductivity and coefficient of thermal expansion and contraction, and good resistance to CO2 / H2S corrosion. It can meet the needs of hot dry rock geothermal extraction. When applied to the inner wall of the well, it helps to reduce the heat loss of the fluid in the well and improve the efficiency of geothermal energy utilization. Attached Figure Description

[0032] Figure 1 The elemental analysis spectrum of the foamed cement slurry prepared in Example 6;

[0033] Figure 2 The X-ray diffraction pattern of the foamed cement slurry prepared in Example 6;

[0034] Figure 3 The image shows a scanning electron microscope (SEM) image of a cross-section of the foamed cement stone formed by the curing of the foamed cement slurry prepared in Example 6. Detailed Implementation

[0035] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0036] This invention provides a foaming composition for cement, comprising an N-fatty acyl amino acid type foaming agent, sodium higher fatty acid, water glass, and an air-entraining agent.

[0037] According to an embodiment of the present invention, the mass of the foaming composition for cement is 100%, wherein the mass of the N-fatty acyl amino acid type foaming agent is 4.5wt%-5.5wt%, the mass of the sodium higher fatty acid is 9wt%-11.1wt%, the mass of the water glass is 51wt%-53.5wt%, and the mass of the air-entraining agent is 32wt%-33.5wt%.

[0038] According to an embodiment of the present invention, the N-fatty acyl amino acid type foaming agent is sodium N-fatty acyl amino acid.

[0039] According to an embodiment of the present invention, the N-fatty acyl amino acid sodium includes at least one of sodium stearoyl lysine, sodium linoleyl glycinate, and sodium oleoyl glutamate.

[0040] According to embodiments of the present invention, the higher sodium fatty acid includes at least one of C14 to C18 sodium fatty acids.

[0041] According to an embodiment of the present invention, the higher fatty acid sodium is at least one selected from sodium hexadecanoate, sodium octadecanoate, and sodium tetradecanoate.

[0042] According to an embodiment of the present invention, the modulus of the water glass is 2.7-3.4; and / or the Baume degree is 48°-52°.

[0043] According to an embodiment of the present invention, the air-entraining agent is a rosin-based air-entraining agent.

[0044] According to embodiments of the present invention, the components of the rosin-based air-entraining agent include sodium rosinate, modified rosin thermal polymer, and rosin salt.

[0045] According to an embodiment of the present invention, the foaming composition for cement is used to generate a stepped-pore foam structure.

[0046] This invention also provides a foamed cement, the raw materials of which include cement base material, cement foaming composition, stabilizer and waterproofing agent;

[0047] The foaming composition for cement is the foaming composition for cement described in the embodiments of the present invention.

[0048] According to an embodiment of the present invention, the total mass of the raw materials of the foamed cement is 100 parts by mass, and the foamed cement includes 55-89 parts by mass of the cement base material, 5-28.4 parts by mass of the foaming composition for cement, 2.8-10 parts by mass of the stabilizer and 3-7 parts by mass of the waterproofing agent.

[0049] According to an embodiment of the present invention, the total mass of the raw materials of the foamed cement is 100 parts by mass, and the foamed cement includes 61.5-62.4 parts by mass of the cement base material, 24.4-25.3 parts by mass of the foaming composition for cement, 8 parts by mass of the stabilizer and 5.2 parts by mass of the waterproofing agent.

[0050] According to embodiments of the present invention, the C2S content in the cementitious material is not less than 45 wt%; and / or the molar ratio of calcium oxide to silicon oxide is in the range of (1.85-2.15):1; and / or

[0051] The 7-day heat of hydration of the cementitious material shall not exceed 220 kJ / kg; and / or

[0052] The specific surface area of ​​the cementitious material ranges from 280 to 320 m². 2 / kg.

[0053] According to an embodiment of the present invention, the cement base material is Grade G oil well cement.

[0054] According to an embodiment of the present invention, the stabilizer is waste concrete; and / or

[0055] The SiO2 content in the waste concrete is not less than 70 wt%; and / or

[0056] The fineness of the waste concrete powder is not less than 320 mesh.

[0057] According to an embodiment of the present invention, the waterproofing agent is ethylene glycol acrylate.

[0058] According to an embodiment of the present invention, the foamed cement stone prepared from the foamed cement has a stepped pore foam structure.

[0059] According to an embodiment of the present invention, the total pore volume of the stepped pore foam structure is taken as 100%, pores with a diameter of 70-200μm account for 2.5%-3.8% of the total pore volume, pores with a diameter of 680-1300μm account for 15%-23% of the total pore volume, and pores with a diameter of 2-4mm account for the remaining percentage of the total pore volume.

[0060] According to an embodiment of the present invention, the foamed cement stone is prepared by using water and the foamed cement in the following steps:

[0061] Step 1. Mix the cement foaming composition with water to obtain a foaming liquid;

[0062] Step 2. Mix the cementitious material, stabilizer and waterproofing agent evenly to obtain the powder to be foamed;

[0063] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared using the foaming liquid and the powder to be foamed at a liquid-to-solid ratio of 0.45. After curing, foamed cement stone with the stepped foam structure is formed.

[0064] The liquid-solid ratio referred to in this embodiment of the invention is the ratio of the volume of the foaming liquid before foaming to the volume of the powder to be foamed; wherein, the volume of the foaming liquid before foaming is the sum of the volumes of the cement foaming composition and water before mixing the cement foaming composition and water in step 1.

[0065] Application of the foamed cement composition provided in the embodiments of the present invention or the foamed cement provided in the embodiments of the present invention in hot dry rock insulation cementing.

[0066] Cement foaming composition

[0067] Information on some of the raw materials used in the following examples / comparative examples is as follows:

[0068] Water glass: Modulus 2.7-3.4, Baumé degree 48°-52°, industrial-grade water glass product purchased from Jinan Xinjiarun New Materials Co., Ltd.

[0069] Rosin-based air-entraining agent: Industrial-grade rosin purchased from Shandong Tengbo Chemical Technology Co., Ltd., whose components include sodium rosinate, modified rosin thermal polymer and rosin salt.

[0070] Unless otherwise specified, all other raw materials used below are commercially available products.

[0071] Example 1

[0072] This embodiment provides a foaming composition for cement, comprising sodium stearoyl lysine, sodium hexadecanoate, water glass, and a rosin-based air-entraining agent; wherein the mass relationship of the four components is as follows: taking the mass of the foaming composition for cement as 100%, sodium stearoyl lysine accounts for 4.8 wt%, sodium hexadecanoate accounts for 10.1 wt%, water glass accounts for 52.4 wt%, and the rosin-based air-entraining agent accounts for 32.7 wt%;

[0073] An exemplary formulation is provided: a foaming composition for cement comprising 0.12 kg sodium stearoyl lysine, 0.25 kg sodium hexadecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0074] Example 2

[0075] This embodiment provides a foaming composition for cement, comprising sodium linoleoylglycinate, sodium octadecanoate, water glass, and a rosin-based air-entraining agent; wherein the mass relationship of the four components is as follows: taking the mass of the foaming composition for cement as 100%, sodium linoleoylglycinate accounts for 4.8 wt%, sodium octadecanoate accounts for 10.1 wt%, water glass accounts for 52.4 wt%, and the rosin-based air-entraining agent accounts for 32.7 wt%;

[0076] An exemplary formulation is provided: a foaming composition for cement, comprising 0.12 kg sodium linoleoyl glycinate, 0.25 kg sodium octadecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0077] Example 3

[0078] This embodiment provides a foaming composition for cement, comprising sodium oleoyl glutamate, sodium tetradecanoate, water glass, and a rosin-based air-entraining agent; wherein the mass relationship of the four components is as follows: taking the mass of the foaming composition for cement as 100%, sodium oleoyl glutamate accounts for 4.8 wt%, sodium tetradecanoate accounts for 10.1 wt%, water glass accounts for 52.4 wt%, and the rosin-based air-entraining agent accounts for 32.7 wt%;

[0079] An exemplary formulation is provided: a foaming composition for cement, comprising 0.12 kg sodium oleoyl glutamate, 0.25 kg sodium tetradecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0080] Example 4

[0081] This embodiment provides a foaming composition for cement, comprising sodium stearoyl lysine, sodium hexadecanoate, water glass, and a rosin-based air-entraining agent; wherein the mass relationship of the four components is as follows: taking the mass of the foaming composition for cement as 100%, sodium stearoyl lysine accounts for 5.5 wt%, sodium hexadecanoate accounts for 11.1 wt%, water glass accounts for 51.4 wt%, and the rosin-based air-entraining agent accounts for 32.0 wt%;

[0082] An exemplary formulation is provided: a foaming composition for cement, comprising 0.14 kg sodium stearoyl lysine, 0.28 kg sodium hexadecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0083] Example 5

[0084] This embodiment provides a foaming composition for cement, comprising sodium stearoyl lysine, sodium hexadecanoate, water glass, and a rosin-based air-entraining agent; wherein the mass relationship of the four components is as follows: taking the mass of the foaming composition for cement as 100%, sodium stearoyl lysine accounts for 4.5 wt%, sodium hexadecanoate accounts for 9.0 wt%, water glass accounts for 53.3 wt%, and the rosin-based air-entraining agent accounts for 33.2 wt%;

[0085] An exemplary formulation is provided: a foaming composition for cement, comprising 0.11 kg sodium stearoyl lysine, 0.22 kg sodium hexadecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0086] Comparative Example 1

[0087] This comparative example provides a foaming composition for cement, which differs from Example 1 in that sodium stearoyl lysine and sodium hexadecanoate are removed.

[0088] An exemplary formulation is provided: a foaming composition for cement comprising 1.3 kg of water glass and 0.81 kg of rosin-based air-entraining agent.

[0089] Comparative Example 2

[0090] This comparative example provides a foaming composition for cement, which differs from Example 1 in that it removes sodium stearoyl lysine.

[0091] An exemplary formulation is provided: a foaming composition comprising 0.25 kg sodium hexadecanoate, 1.3 kg water glass and 0.81 kg rosin-based air-entraining agent.

[0092] Comparative Example 3

[0093] This comparative example provides a foaming composition for cement, which differs from Example 1 in that sodium hexadecanoate is removed.

[0094] An exemplary formulation is provided: a foaming composition comprising 0.12 kg of sodium stearoyl lysine, 1.3 kg of water glass and 0.81 kg of rosin-based air-entraining agent.

[0095] Foamed cement, foamed cement slurry and foamed cement stone

[0096] Information on some of the raw materials used in the following examples / comparative examples is as follows:

[0097] Grade G oil well cement: C2S (dicalcium silicate) content is 52.5%, calcium-silicon ratio (molar ratio of calcium oxide to silicon oxide) is 1.98:1, and specific surface area is 300 m². 2 / kg, 7d heat of hydration ≤220kJ / kg, purchased from Shandong Huayin Special Cement Co., Ltd.;

[0098] Waste concrete: purchased from Shanghai Yizhao Municipal Engineering Materials Co., Ltd.; after crushing and grinding, the fineness of the powder was controlled to be 320 mesh, and the SiO2 content in the powder was 71.6 wt%.

[0099] Unless otherwise specified, all other raw materials used below are commercially available products.

[0100] Example 6

[0101] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 1, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 62 parts by mass of G-grade oil well cement, 24.8 parts by mass of the foaming composition for cement provided in Example 1, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0102] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.2 kg of Grade G oil well cement, 2.48 kg of the foaming composition for cement provided in Example 1, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate.

[0103] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0104] Step 1. Mix 2.48 kg of the cement foaming composition provided in Example 1 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0105] Step 2. Mix 6.2 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the foaming powder;

[0106] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0107] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0108] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0109] Example 7

[0110] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 2, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 62 parts by mass of G-grade oil well cement, 24.8 parts by mass of the foaming composition for cement provided in Example 2, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0111] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.2 kg of Grade G oil well cement, 2.48 kg of the foaming composition for cement provided in Example 2, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate;

[0112] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0113] Step 1. Mix 2.48 kg of the cement foaming composition provided in Example 2 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0114] Step 2. Mix 6.2 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the foaming powder;

[0115] Step 3: Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0116] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0117] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0118] Example 8

[0119] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 3, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 62 parts by mass of G-grade oil well cement, 24.8 parts by mass of the foaming composition for cement provided in Example 3, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0120] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.2 kg of Grade G oil well cement, 2.48 kg of the foaming composition for cement provided in Example 3, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate;

[0121] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0122] Step 1. Mix 2.48 kg of the cement foaming composition provided in Example 3 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0123] Step 2. Mix 6.2 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the foaming powder;

[0124] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0125] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0126] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0127] Example 9

[0128] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 4, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is calculated as 100 parts by mass, the foamed cement includes 61.5 parts by mass of G-grade oil well cement, 25.3 parts by mass of the foaming composition for cement provided in Example 4, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0129] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.15 kg of Grade G oil well cement, 2.53 kg of the cement foaming composition provided in Example 4, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate;

[0130] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0131] Step 1. Mix 2.53 kg of the cement foaming composition provided in Example 4 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0132] Step 2. Mix 6.15 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the powder to be foamed;

[0133] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0134] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0135] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0136] Example 10

[0137] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 5, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 62.4 parts by mass of G-grade oil well cement, 24.4 parts by mass of the foaming composition for cement provided in Example 5, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0138] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.24 kg of Grade G oil well cement, 2.44 kg of the foaming composition for cement provided in Example 5, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate;

[0139] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0140] Step 1. Mix 2.44 kg of the cement foaming composition provided in Example 5 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0141] Step 2. Mix 6.24 kg of Grade G oil well cement, 0.8 kg of waste concrete, and 0.52 kg of ethylene glycol acrylate, stir evenly, and obtain the powder to be foamed;

[0142] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0143] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0144] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0145] Example 11

[0146] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 1, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 55 parts by mass of G-grade oil well cement, 28.4 parts by mass of the foaming composition for cement provided in Example 1, 10 parts by mass of waste concrete, and 6.6 parts by mass of ethylene glycol acrylate;

[0147] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 5.5 kg of Grade G oil well cement, 2.84 kg of the foaming composition for cement provided in Example 1, 1 kg of waste concrete and 0.66 kg of ethylene glycol acrylate;

[0148] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0149] Step 1. Mix 2.84 kg of the cement foaming composition provided in Example 1 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0150] Step 2. Mix 5.5 kg of Grade G oil well cement, 1 kg of waste concrete and 0.66 kg of ethylene glycol acrylate, stir evenly to obtain the foaming powder;

[0151] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0152] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0153] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0154] Example 12

[0155] This embodiment provides a foamed cement, the raw materials of which include G-grade oil well cement, the foaming composition for cement provided in Example 1, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is calculated as 100 parts by mass, the foamed cement includes 89 parts by mass of G-grade oil well cement, 5.2 parts by mass of the foaming composition for cement provided in Example 1, 2.8 parts by mass of waste concrete, and 3 parts by mass of ethylene glycol acrylate;

[0156] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 8.9 kg of Grade G oil well cement, 0.52 kg of the cement foaming composition provided in Example 1, 0.28 kg of waste concrete and 0.3 kg of ethylene glycol acrylate;

[0157] The exemplary foamed cement formula provided in this embodiment is used to prepare foamed cement slurry:

[0158] Step 1. Mix 0.52 kg of the cement foaming composition provided in Example 1 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0159] Step 2. Mix 8.9 kg of Grade G oil well cement, 0.28 kg of waste concrete and 0.3 kg of ethylene glycol acrylate, stir evenly to obtain the powder to be foamed;

[0160] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0161] The foamed cement slurry prepared in this embodiment was cured to form a foamed cement stone sample:

[0162] The foamed cement slurry prepared in this embodiment was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0163] Comparative Example 4

[0164] This comparative example provides a foamed cement, the raw materials of which include Grade G oil well cement, the cement foaming composition provided in Comparative Example 1, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 65.7 parts by mass of Grade G oil well cement, 21.1 parts by mass of the cement foaming composition provided in Comparative Example 1, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0165] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.57 kg of Grade G oil well cement, 2.11 kg of the cement foaming composition provided in Comparative Example 1, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate.

[0166] The exemplary foamed cement formula provided in this comparative example is used to prepare foamed cement slurry:

[0167] Step 1. Mix 2.11 kg of the cement foaming composition provided in Comparative Example 1 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0168] Step 2. Mix 6.57 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the powder to be foamed;

[0169] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0170] The foamed cement slurry prepared in this comparative example was cured to form a foamed cement stone sample:

[0171] The foamed cement slurry prepared in this comparative example was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0172] Comparative Example 5

[0173] This comparative example provides a foamed cement, the raw materials of which include G-grade oil well cement, the cement foaming composition provided in Comparative Example 2, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 63.2 parts by mass of G-grade oil well cement, 23.6 parts by mass of the cement foaming composition provided in Comparative Example 2, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0174] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.32 kg of Grade G oil well cement, 2.36 kg of the cement foaming composition provided in Comparative Example 2, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate.

[0175] The exemplary foamed cement formula provided in this comparative example is used to prepare foamed cement slurry:

[0176] Step 1. Mix 2.36 kg of the cement foaming composition provided in Comparative Example 2 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0177] Step 2. Mix 6.32 kg of Grade G oil well cement, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate, stir evenly to obtain the powder to be foamed;

[0178] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0179] The foamed cement slurry prepared in this comparative example was cured to form a foamed cement stone sample:

[0180] The foamed cement slurry prepared in this comparative example was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0181] Comparative Example 6

[0182] This comparative example provides a foamed cement, the raw materials of which include Grade G oil well cement, the cement foaming composition provided in Comparative Example 3, waste concrete, and ethylene glycol acrylate; wherein, the mass relationship of the four raw materials is as follows: the total mass of the raw materials of the foamed cement is taken as 100 parts by mass, the foamed cement includes 64.5 parts by mass of Grade G oil well cement, 22.3 parts by mass of the cement foaming composition provided in Comparative Example 3, 8 parts by mass of waste concrete, and 5.2 parts by mass of ethylene glycol acrylate;

[0183] An exemplary foamed cement formulation is provided: a foamed cement whose raw materials include 6.45 kg of G-grade oil well cement, 2.23 kg of the foaming composition for cement provided in Comparative Example 3, 0.8 kg of waste concrete and 0.52 kg of ethylene glycol acrylate.

[0184] The exemplary foamed cement formula provided in this comparative example is used to prepare foamed cement slurry:

[0185] Step 1. Mix 2.23 kg of the cement foaming composition provided in Comparative Example 3 with water, and stir to dissolve the cement foaming composition evenly to obtain a foaming liquid;

[0186] Step 2. Mix 6.45kg of Grade G oil well cement, 0.8kg of waste concrete, and 0.52kg of ethylene glycol acrylate, stir evenly, and obtain the powder to be foamed;

[0187] Step 3. Following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method, foamed cement slurry is prepared with a liquid-to-solid ratio of 0.45.

[0188] The foamed cement slurry prepared in this comparative example was cured to form a foamed cement stone sample:

[0189] The foamed cement slurry prepared in this comparative example was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in foamed cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0190] Comparative Example 7

[0191] This comparative example provides a conventional high-temperature cementing cement, the raw materials of which include G-grade oil well cement and waste concrete; wherein, the mass relationship between the two raw materials is as follows: the total mass of the conventional high-temperature cementing cement is taken as 100%, the conventional high-temperature cementing cement includes 65wt% G-grade oil well cement and 35wt% waste concrete.

[0192] An exemplary conventional high-temperature cementing formula is provided: a conventional high-temperature cementing cement whose raw materials include 6.5 kg of Grade G oil well cement and 3.5 kg of waste concrete.

[0193] The exemplary conventional high-temperature cementing cement formulation provided in this comparative example is used to prepare conventional high-temperature cementing slurry:

[0194] 6.5 kg of Grade G oil well cement and 3.5 kg of waste concrete were mixed evenly, and conventional high-temperature cement slurry was prepared by following the steps specified in the cement slurry preparation section of the national standard GB / T 19139-2012 Oil Well Cement Test Method with a liquid-to-solid ratio of 0.45.

[0195] The conventional high-temperature cementing slurry prepared in this comparative example was solidified to form a conventional high-temperature cementing stone sample:

[0196] The conventional high-temperature cement slurry prepared in this comparative example was poured into a copper mold and then placed in a high-temperature curing autoclave. It was cured at 300°C for 2 days, 7 days, and 14 days, resulting in conventional high-temperature cement stone samples with curing times of 2 days, 7 days, and 14 days.

[0197] Characterization of foamed cement slurry

[0198] 1. Elemental analysis of foamed cement slurry

[0199] Taking the foamed cement slurry prepared in Example 6 as an example, SEM scanning electron microscopy energy dispersive spectroscopy analysis was performed to analyze the elemental composition. The results are shown in […]. Figure 1 .

[0200] Figure 1 The results show that the foamed cement slurry prepared in Example 6 contains C, N, O, Na, Si, P and Cu elements. The Cu element comes from the residue of the sodium hexadecanoate synthesis process, while the C, N, O, Na, Si and P elements correspond to the elemental composition of the various raw materials of the foamed cement slurry.

[0201] The elemental analysis results of Examples 7 to 12 show that the elemental composition of the foamed cement slurry provided in each example corresponds to the elemental composition of its raw materials.

[0202] 2. XRD pattern determination of foamed cement slurry

[0203] Taking the foamed cement slurry prepared in Example 6 as an example, XRD pattern analysis was performed, and the results are shown in [Figure 6]. Figure 2 .

[0204] Figure 2 This indicates that the foamed cement slurry prepared in Example 6 is mainly composed of silicon, oxygen, and calcium.

[0205] The XRD test results of the foamed cement slurry prepared in Examples 7 to 12 also showed that the components of the foamed cement slurry provided in each example were mainly silicon, oxygen and calcium.

[0206] Morphology of foamed cement stone

[0207] 1. Morphological observation of foamed cement stone

[0208] Figure 3 The image shown is a scanning electron microscope (SEM) image of the foamed cement stone sample prepared in Example 6 with a curing time of 14 days. It reveals a fine, stepped pore structure with delicate pore walls and few microcracks, indicating good compressive strength and elasticity.

[0209] Scanning electron microscopy revealed that the foamed cement stone samples prepared in Examples 7 to 12, with a curing time of 14 days, also exhibited similar characteristics to... Figure 3 The similar morphology shown.

[0210] Stepped-pore foam structure of foamed cement stone

[0211] The stepped pore foam structure of the cross-section of the foamed cement stone prepared in Examples 6 to 12 with a curing time of 14 days was observed using scanning electron microscopy and metallographic microscopy, as detailed in Table 1.

[0212] Table 1. Stepwise porous foam structure of cross-sections of foamed cement stone prepared in Examples 6 to 12 with a curing time of 14 days.

[0213]

[0214] No stepped pore foam structure as seen in Examples 6 to 12 was observed in the cross-sections of the foamed cement stone samples prepared in Comparative Examples 4 to 7 and the conventional high-temperature cementing samples.

[0215] Performance evaluation of foamed cement stone

[0216] The foamed cement stone samples prepared in Examples 6 to 12, Comparative Examples 4 to 6, and the conventional high-temperature cementing stone sample prepared in Comparative Example 7 were tested for compressive strength, density, elastic modulus, thermal conductivity, coefficient of thermal expansion and contraction, and resistance to CO2 / H2S corrosion to evaluate the performance of the foamed cement stone.

[0217] (1) The compressive strength of foamed cement stone samples and conventional high-temperature cementing samples with curing times of 2d, 7d and 14d obtained from each embodiment and comparative example was measured. The results are shown in Table 1.

[0218] (2) The density, elastic modulus, thermal conductivity and thermal expansion coefficient of foamed cement stone samples with a curing time of 14 days and conventional high temperature cementing samples obtained from each embodiment and comparative example were measured respectively.

[0219] Specifically, the elastic modulus was determined using a triaxial stress testing machine;

[0220] Thermal conductivity was determined using the heat flow method.

[0221] The coefficient of thermal expansion and contraction was determined using the standard T 0577-2020 Test Method for Linear Expansion Coefficient of Cement Concrete.

[0222] The results of the determination of density, elastic modulus, thermal conductivity and coefficient of thermal expansion and contraction are shown in Table 2.

[0223] (3) The CO2 / H2S corrosion resistance of foamed cement stone samples with a curing time of 14 days and conventional high-temperature cementing cement stone samples obtained from each embodiment and comparative example were determined.

[0224] Specifically, foamed cement stone samples and conventional high-temperature cement stone samples were placed in an environment of "20% H2S + 15% CO2" and aged at 85℃ for 7 days. After aging, the samples were removed and their compressive strength and permeability were measured to reflect their resistance to CO2 / H2S corrosion. The permeability was measured according to the steps specified in "7. Determination of Permeability" of the national standard GB / T29172-2012 "Core Analysis Methods". The "20% H2S + 15% CO2" environment was water containing dissolved H2S and CO2 gases, with the water volume accounting for 100%, H2S gas volume accounting for 20%, and CO2 gas volume accounting for 15%.

[0225] The results are shown in Table 3.

[0226] Table 2. Performance of foamed cement stone samples and conventional high-temperature cementing stone samples

[0227]

[0228] Table 3. CO2 / H2S corrosion resistance of foamed cement stone samples and conventional high-temperature cementing samples

[0229]

[0230] As shown in Tables 2 and 3, the properties of the cement stone samples obtained by curing the foamed cement slurry provided in Examples 6 to 12 at 300℃ for 2 to 14 days are as follows: the average compressive strength of the foamed cement stone samples formed after curing for 2 days, 7 days, and 14 days are 10 MPa, 11.7 MPa, and 14.2 MPa, respectively; and the average density of the foamed cement stone sample formed after curing for 14 days is 1 g / cm³. 3 The average elastic modulus is 2.8 GPa, the average thermal conductivity is approximately 0.23 W / m·K, and the average coefficient of thermal expansion is 7°C. -6 / ℃; Foamed cement stone samples cured for 14 days were placed in an environment of "20% H2S + 15% CO2" and aged at 85℃ for 7 days, with an average compressive strength of 7.8 MPa and an average permeability of 0.0074 mD. In contrast, the conventional high-temperature cement stone provided in Comparative Example 7 had a significantly higher density and a significantly higher coefficient of thermal expansion than the foamed cement stone provided by this invention. Therefore, the foamed cement stone formed by curing the foamed cement slurry prepared further from the foaming composition for cement provided by this invention has higher compressive strength, lower density and elastic modulus, lower thermal conductivity and coefficient of thermal expansion, and better resistance to CO2 / H2S corrosion.

[0231] Furthermore, comparing Example 6, Comparative Example 5, and Comparative Example 6 with Comparative Example 4, it can be seen that: (1) In terms of compressive strength: the compressive strength of foamed cement stone cured for 2 days in Example 6, Comparative Example 5, and 6 increased by 64.5%, decreased by 3.2%, and decreased by 1.6%, respectively; the compressive strength of foamed cement stone cured for 7 days in Example 6, Comparative Example 5, and 6 increased by 60.3%, increased by 1.4%, and decreased by 2.7%; the compressive strength of foamed cement stone cured for 14 days in Example 6, Comparative Example 5, and 6 increased by 58.9%, decreased by 1.1%, and increased by 1.1%; 2) Density: The density of foamed cement stone cured for 14 days in Example 6, Comparative Examples 5 and 6 decreased by 6.3%, 0.9%, and 1.8%, respectively; (3) Elastic modulus: The elastic modulus of foamed cement stone cured for 14 days in Example 6, Comparative Examples 5 and 6 decreased by 32.6%, 7.0%, and 4.7%, respectively; (4) Thermal conductivity: The density of foamed cement stone cured for 14 days in Example 6, Comparative Examples 5 and 6 decreased by 51.1%, 27.7%, and 17%, respectively; (5) Coefficient of thermal expansion and contraction: The density of foamed cement stone cured for 14 days in Example 6, Comparative Examples 5 and 6 decreased by 51.1%, 27.7%, and 17%, respectively; The density of foamed cement stone cured for 14 days in Examples 5 and 6 decreased by 28.6%, increased by 2.0%, and decreased by 1.0%, respectively; (6) Regarding resistance to CO2 / H2S corrosion: After being placed in an environment of "20% H2S + 15% CO2" and aged at 85°C for 7 days, the compressive strength of foamed cement stone cured for 14 days in Examples 6 and Comparative Examples 5 and 6 increased by 56.9%, decreased by 2.0%, and increased by 3.9%, respectively, and the permeability decreased by 46.7%, decreased by 13.3%, and decreased by 20.0%, respectively; Based on the above comparison, combined with Examples 6 and Comparative Examples 4 to 6 The differences in the foamed cement slurry formulations (i.e., Example 6, compared to Comparative Example 4, simultaneously added sodium stearoyl lysine and hexadecanoic acid; Comparative Example 5, compared to Comparative Example 4, added sodium hexadecanoate; and Comparative Example 6, compared to Comparative Example 4, added sodium stearoyl lysine) indicate that in the foamed cement composition provided by the present invention, there is a synergistic effect between the N-fatty acyl amino acid type foaming agent and the sodium higher fatty acid. The combined use of the two in the foamed cement composition forms a cluster of bubbles with a stepped diameter distribution in the foamed cement, which helps the foamed cement to form an excellent foam structure and improves the performance of the foamed cement stone.

[0232] Several application examples are provided below to better illustrate the actual use effect of foamed cement slurry prepared by further formulation of the foaming composition for cement provided by the present invention.

[0233] Application Example 1

[0234] In a certain well (3950m deep, bottom temperature 180℃) within a certain block, the foamed cement slurry prepared using the foamed cement provided by this invention was applied at a flow rate of 20m³. 3The injection temperature is 25℃, and the solidification forms foamed cement stone. The heat exchange power can reach 644kW, and 19540GJ of geothermal energy can be obtained in one year.

[0235] The heat exchange capacity of adjacent wells using G-grade oil well cement is increased by 42%.

[0236] Application Example 2

[0237] In a certain well in a certain block (well depth 3000m, bottom temperature 140℃), the foam cement slurry prepared by the foam cement provided by this invention was applied. When the injection temperature was 40℃, it solidified to form foam cement stone. When the carbon dioxide injection pressure was only 3MPa, the power generation capacity could reach 3.4MW.

[0238] Compared to using G-grade oil well cement, the power generation of adjacent wells increased by 28%.

[0239] Application Example 3

[0240] In a certain well in a certain block (well depth 1700m, bottom temperature 103℃), the foam cement slurry prepared by the foam cement provided by this invention was applied and solidified to form foam cement stone. The maximum heat generation power can reach 367kW, and the power generation power can reach 0.135MW when carbon dioxide is injected at a pressure of 6MPa.

[0241] Compared to using G-grade oil well cement, the power generation of adjacent wells increased by 33%.

[0242] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A foaming composition for cement, comprising an N-fatty acyl amino acid type foaming agent, sodium higher fatty acid, water glass, and an air-entraining agent.

2. The foaming composition for cement according to claim 1, characterized in that, The cement foaming composition comprises 100% by weight, wherein the N-fatty acyl amino acid foaming agent accounts for 4.5wt%-5.5wt%, the sodium higher fatty acid accounts for 9wt%-11.1wt%, the water glass accounts for 51wt%-53.5wt%, and the air-entraining agent accounts for 32wt%-33.5wt%.

3. The foaming composition for cement according to claim 2, characterized in that, The N-fatty acyl amino acid type foaming agent is sodium N-fatty acyl amino acid.

4. The foaming composition for cement according to claim 3, characterized in that, The N-fatty acyl amino acid sodium salt includes at least one of sodium stearoyl lysine, sodium linoleyl glycine, and sodium oleoyl glutamate.

5. The foaming composition for cement according to any one of claims 1 to 4, characterized in that, The higher fatty acid sodium salts include at least one of C14 to C18 fatty acid sodium salts.

6. The foaming composition for cement according to claim 5, characterized in that, The water glass has a modulus of 2.7-3.4 and / or a Baume degree of 48°-52°.

7. The foaming composition for cement according to claim 6, characterized in that, The air-entraining agent is a rosin-based air-entraining agent.

8. The foaming composition for cement according to claim 7, characterized in that, The foaming composition for cement is used to produce a stepped-pore foam structure.

9. A foamed cement, the raw materials of which include cementitious base material, a foaming composition for cement, a stabilizer and a waterproofing agent; The foaming composition for cement is the foaming composition for cement as described in any one of claims 1 to 8.

10. The foamed cement according to claim 9, characterized in that, The total mass of the raw materials of the foamed cement is calculated as 100 parts by mass. The foamed cement includes 55-89 parts by mass of the cement base material, 5-28.4 parts by mass of the foaming composition for cement, 2.8-10 parts by mass of the stabilizer and 3-7 parts by mass of the waterproofing agent.

11. The foamed cement according to claim 9 or 10, characterized in that, The cementitious material contains not less than 45 wt% C2S; and / or the molar ratio of calcium oxide to silicon oxide is in the range of (1.85-2.15):1; and / or The 7-day heat of hydration of the cementitious material is not higher than 220 kJ / kg.

12. The foamed cement according to claim 11, characterized in that, The stabilizer is waste concrete; And / or the SiO2 content in the waste concrete is not less than 70 wt%; and / or The fineness of the waste concrete powder is not less than 320 mesh.

13. The foamed cement according to claim 12, characterized in that, The foamed cement stone prepared from the foamed cement has a stepped pore foam structure.

14. The foamed cement according to claim 13, characterized in that, The total pore volume of the stepped pore foam structure is taken as 100%. Pores with a diameter of 70-200μm account for 2.5%-3.8% of the total pore volume, pores with a diameter of 680-1300μm account for 15%-23% of the total pore volume, and pores with a diameter of 2-4mm account for the remaining percentage of the total pore volume.

15. The application of the foaming composition for cement according to any one of claims 1 to 8 or the foamed cement according to any one of claims 9 to 14 in hot dry rock insulation cementing.

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