High-temperature large-temperature-difference early-strength low-density well cementation cement slurry and preparation method thereof

Abstract

The invention discloses high-temperature large-temperature-difference early-strength low-density well cementation cement slurry and a preparation method thereof, and relates to the technical field of oil and gas well cementation. The well cementation cement slurry comprises the following components in parts by mass: 100 parts of oil well cement; 15-35 parts of a high-temperature strength stabilizer; 10-30 parts of a lightening agent; 0.2 to 0.6 part of an early strength agent; 0.3 to 0.7 part of a high-temperature suspension stabilizer; 1-5 parts of a high-temperature fluid loss agent; 0.3 to 0.7 part of a high-temperature retarder; and 50-70 parts of water. The problems that in the prior art, large-temperature-difference low-density cement paste is poor in rheological property, too large in water loss, poor in high-temperature stability, slow in strength development and the like are solved, safe well cementation construction of a long-sealing-section easy-leakage stratum is achieved, and therefore efficient and safe exploitation of deep stratum oil and gas resources is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas well cementing, and in particular to a high-temperature, large-temperature-difference, early-strength, low-density cementing slurry and a preparation method thereof. Background Art

[0002] With the steady growth of my country's economy, the demand for oil and gas resources has continued to rise. Shallow and easily recoverable oil and gas resources are gradually depleted, which has gradually shifted the focus of oil field exploration and development to deep formations. Deep formations are rich in oil and gas resources. my country's deep oil resources exceed 20 billion tons and deep natural gas resources exceed 100 trillion cubic meters, which provides a broad space for the sustainable development of my country's oil industry.

[0003] The geological conditions of deep oil and gas layers are relatively complex, and the burial depth is mostly greater than 5000m. The number of wells with long sealing sections is increasing, and the long sealing section cementing mainly adopts one-time cementing technology. At present, the bottom hole temperature of the leaky layer in the long sealing section generally exceeds 150℃, which puts strict requirements on the high temperature resistance of cement slurry. In addition, in order to prevent the formation from leaking and improve the efficiency and quality of cementing, low-density cement slurry is usually used for cementing in the long sealing section. Low-density cement slurry itself has a low solid content and poor stability under high temperature conditions, which is prone to cement slurry stratification, high-temperature sedimentation and other problems. At the same time, due to the long one-time return of cement slurry in the long sealing section, the temperature difference between the top and bottom of the cement slurry column is large, the bottom hole temperature exceeds 150°C, and the top temperature is around 60°C, with a temperature difference of up to 90°C. Under the action of high-temperature retarder, the strength of the top cement slurry develops slowly, and even slow setting or super-slow setting occurs, which seriously affects the subsequent construction progress and cannot guarantee the cementing quality of the long sealing section. Therefore, it poses a severe challenge to the high temperature and large temperature difference performance of low-density cement slurry.

[0004] As the depth of the well increases, the length of the long sealing section becomes longer and longer, and the temperature difference between the bottom and the top of the well becomes larger and larger. However, the existing high-temperature, large temperature difference, low-density cementing cement is difficult to use. The high-temperature, large temperature difference, low-density cementing cement slurry used in the prior art has the following problems: (1) Poor high-temperature thickening performance: The solid phase components of low-density cementing cement slurry are complex and the content is relatively low, the water-cement ratio is relatively high, and there are many types of high-temperature admixtures, which makes it difficult to adjust the thickening time of low-density cement slurry and prone to abnormal high-temperature gelling. Specifically, the high-temperature thickening curve of the cement slurry shows "bulging" and "stepping" and other unmeasured phenomena, which leads to poor cementing quality; (2) High-temperature strength decay and slow strength development of cement slurry in the top low-temperature area: Low High-density cement slurry is prone to high-temperature strength decay in high-temperature environments above 110°C. In addition, due to the large water-to-cement ratio of existing low-density cement slurry and the small amount of solid phase material, under the action of high-temperature retarders, the strength of low-density cement slurry develops slowly in the low-temperature area at the top of the well, and even slow setting and super-slow setting phenomena occur; (3) Poor high-temperature stability: Low-density cement slurry has a high water-to-cement ratio and small amount of solid phase material. Under the action of high temperature, the lightener in the cement slurry floats up and the remaining solid phase materials sink, which does not lead to poor high-temperature sedimentation stability. Summary of the invention

[0005] In order to overcome the defects and shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high-temperature, large temperature difference, early-strength, low-density cementing slurry and a preparation method thereof, so as to solve the problems of poor rheological properties, excessive water loss, poor high-temperature stability, slow strength development, etc. of the large temperature difference, low-density cement slurry in the prior art, and realize safe cementing construction of leaky formations with long sealing sections, thereby ensuring the efficient and safe exploitation of oil and gas resources in deep formations.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a high-temperature, large-temperature-difference, early-strength, low-density cementing slurry, comprising the following components by mass:

[0008]

[0009] In some embodiments of the present invention, the oil well cement is a mixture of G-grade cement and D-grade cement, and the main mineral composition of the oil well cement is as follows: C3S: 60-68wt%, C2S: 20-25wt%, C3A: 0-1wt%, C4AF: 12-14wt%; the physical properties of the oil well cement meet the following requirements: specific surface area ≥400m 2 / kg, SO3 content ≤3wt%.

[0010] In some embodiments of the present invention, the high temperature strength stabilizer is a mixture of quartz sand, kyanite powder, medical stone and metakaolin; the physical properties of the quartz sand meet the following requirements: specific surface area ≥500kg / m 3 The physical properties of the kyanite powder meet the following requirements: specific surface area ≥ 500 kg / m 3 The physical properties of the medical stone meet the following requirements: specific surface area ≥ 500 kg / m 3 The physical properties of the metakaolin satisfy: specific surface area ≥ 1000kg / m 3 .

[0011] In some embodiments of the present invention, the lightening agent is one or a mixture of poplar wood powder, rubber powder, and plastic powder; the physical properties of the poplar wood powder meet the following requirements: density ≤ 0.40 g / cm 3 , specific surface area ≥300kg / m 3 ; The physical properties of the rubber powder meet the following requirements: density ≤ 1.3 g / cm 3 , specific surface area ≥500kg / m 3 ; The physical properties of the plastic powder meet the following requirements: density ≤ 1.5 g / cm 3 , specific surface area ≥500kg / m 3 .

[0012] In some embodiments of the present invention, the early strength agent is a crystal nucleus type early strength agent, including one or more of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate. The particle size range of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate is between 50 and 100 nm.

[0013] In some embodiments of the present invention, the high temperature suspension stabilizer is a mixture of polyvinyl alcohol 1788, hectorite powder, and dolomite powder; the physical properties of the polyvinyl alcohol 1788 meet the following requirements: purity ≥ 93.5%, specific surface area ≥ 200 kg / m 3 ; The physical properties of the hectorite powder meet the following requirements: specific surface area ≥ 350kg / m 3 ; The physical properties of the dolomite powder meet the following requirements: specific surface area ≥ 1000kg / m 3 .

[0014] In some embodiments of the present invention, the high-temperature fluid loss agent is a G33S fluid loss agent, which is polymerized and modified from AMPS, low molecular weight amide, polyhydroxy carboxylic acid, and the like.

[0015] In some embodiments of the present invention, the high temperature retarder is a random copolymer with a molecular weight between 20,000 and 40,000, which is prepared by free radical aqueous solution polymerization using 30 to 45 parts by weight of acrylamide, 30 to 40 parts by weight of maleic anhydride, 10 to 20 parts by weight of 3-allyloxy-2-hydroxy-1-propanesulfonate and 5 to 10 parts by weight of dimethyldiallylammonium chloride as monomers and 2 to 4 parts of sodium bisulfite-ammonium persulfate as a composite initiator.

[0016] In some embodiments of the present invention, the preparation method of the high temperature retarder is as follows:

[0017] S1. At room temperature, add 30 to 45 parts of acrylamide, 30 to 40 parts of maleic anhydride, 10 to 20 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate, and 5 to 10 parts of dimethyldiallylammonium chloride to 100 parts of water, and fully dissolve and mix to obtain a first mixed solution;

[0018] S2. At room temperature, adjusting the pH of the first mixed solution to 7-8 using a sodium hydroxide solution having a mass concentration of 20% to obtain a second mixed solution;

[0019] S3. At room temperature, add 1 to 2 parts of sodium bisulfite to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a third mixed solution; add 1 to 2 parts of ammonium persulfate to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a fourth mixed solution;

[0020] S4, transferring the second mixed liquid to a reactor with a stirring device, introducing nitrogen to remove oxygen in the reactor and maintaining a nitrogen atmosphere, stirring and heating the second mixed liquid to 60° C., and then using a constant pressure funnel device to drop the third mixed liquid into the second mixed liquid, and after the dropwise addition is completed, also using a constant pressure funnel device to drop the fourth mixed liquid into the second mixed liquid, and after the dropwise addition is completed, a fifth mixed liquid is obtained; preferably, the stirring speed during stirring and heating is 200 r / min, and the dropping speeds of the third mixed liquid and the fourth mixed liquid are both 10 drops / min;

[0021] S5. The fifth mixed liquid is kept at 60° C. for 3 hours, then naturally cooled to 45° C. and kept at 45° C. for 1-2 hours, and then taken out to obtain a ninth mixed liquid, which is the high-temperature retarder.

[0022] The present invention also provides a method for preparing a high-temperature, large temperature difference, early-strength, low-density cementing slurry, comprising the following operations: weighing, by mass, 100 parts of oil well cement, 10 to 35 parts of high-temperature strength stabilizer, 10 to 30 parts of lightener, 0.2 to 0.6 parts of early strength agent, 0.3 to 0.7 parts of high-temperature suspension stabilizer, 1 to 5 parts of high-temperature fluid loss reducer, 0.3 to 0.7 parts of high-temperature retarder and 50 to 70 parts of water, and preparing the high-temperature, large temperature difference, early-strength, low-density cementing slurry in accordance with "GB / T19139-2012 Test Method for Oil Well Cement".

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Compared with the prior art, the high-temperature, large temperature difference, low-density cementing slurry provided by the present invention has better rheological properties, no free liquid, low water loss, better high-temperature sedimentation stability, excellent high-temperature thickening performance, adjustable thickening time, and no abnormal gelation phenomenon during the cement slurry thickening process. In addition, the high-temperature strength of the cement stone in the high-temperature area of ​​the high-temperature, large temperature difference, low-density cementing slurry of the present invention does not decay, and the early strength of the cement mudstone in the low-temperature area is high, which effectively guarantees the cementing quality of the leaky layer in the long sealing section and ensures the efficient and safe exploitation of oil and gas resources in deep formations.

[0025] 2. Compared with the prior art, the lightening agents used in the high-temperature, large temperature difference, low-density cementing slurry provided by the present invention are mainly one or more of wood powder, rubber powder, and plastic powder. The above lightening agents are all inert materials and play a good lightening role in the cement slurry. They are cheap and widely available, fully realizing waste utilization, effectively reducing the cost of cementing materials, and achieving the advantages of cost reduction and efficiency improvement.

[0026] 3. Compared with the prior art, the early strength agent used in the high-temperature, large temperature difference, low-density cementing cement slurry provided by the present invention is a crystal nucleus type early strength agent, which has no obvious promoting effect on the hydration reaction rate in the initial stage of cement hydration reaction, and the induction period of the cement slurry is basically unchanged. It mainly acts in the late stage of hydration acceleration period, promotes the formation of hydrated calcium silicate gel and increases the growth rate of calcium vanadium. Therefore, the early strength agent has little effect on the high-temperature thickening time of high-temperature, large temperature, low-density cementing cement, and can effectively promote the strength development of low-density cement slurry in the low-temperature region.

[0027] 4. Compared with the prior art, the retarder used in the high-temperature, large temperature difference, low-density cementing slurry provided by the present invention is a zwitterionic retarder, which contains two oppositely charged ionic sulfonic acid groups (-SO3 - ) and quaternary ammonium groups (R 4 N +), this special structure enables it to effectively adsorb on the surface of cement particles during the hydration process, forming a stable double electrical layer, preventing the cement particles from further agglomerating and hardening, thereby delaying the setting time of oil well cement. When the ambient temperature changes, the charge state of the zwitterions will adjust, changing its adsorption capacity on cement particles. When the temperature rises, its adsorption capacity increases, which can more effectively prevent the hardening of large temperature difference cementing slurry. Conversely, when the temperature drops, its adsorption capacity decreases, allowing large temperature difference cementing slurry to harden normally, thus solving the contradiction between the long high temperature thickening time and slow low temperature strength development of large temperature difference cementing slurry, and achieving the characteristics of high temperature slow setting and low temperature early strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the high temperature thickening curve of the high temperature, large temperature difference, early strength and low density cementing slurry prepared in Example 1.

[0029] Figure 2 This is the high temperature thickening curve of the high temperature, large temperature difference, early strength and low density cementing slurry prepared in Example 3.

[0030] Figure 3 This is the high temperature thickening curve of the high temperature, large temperature difference, early strength and low density cementing slurry prepared in Example 5.

[0031] Figure 4 This is the high temperature thickening curve of the high temperature, large temperature difference and low density cementing slurry prepared in Comparative Example 1.

[0032] Figure 5 This is the high-temperature thickening curve of the high-temperature, large temperature difference, low-density cementing slurry prepared in Comparative Example 2.

[0033] Figure 6 This is the high temperature thickening curve of the high temperature, large temperature difference and low density cementing slurry prepared in comparative example 3. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. The terms "first", "second", etc. in the present invention are used to distinguish different objects, rather than to describe a specific order.

[0035] In the embodiment of the present invention, the oil well cement is a mixture of G-grade cement and D-grade cement, and the main mineral composition of the oil well cement is as follows: C3S: 60-68wt%, C2S: 20-25wt%, C3A: 0-1wt%, C4AF: 12-14wt%; the physical properties of the oil well cement meet the following requirements: specific surface area ≥400m 2 / kg, SO3 content ≤3wt%.

[0036] In the embodiment of the present invention, the high temperature strength stabilizer is a mixture of quartz sand, kyanite powder, medical stone and metakaolin; the physical properties of the quartz sand meet the following requirements: specific surface area ≥500kg / m 3 The physical properties of the kyanite powder meet the following requirements: specific surface area ≥ 500 kg / m 3 The physical properties of the medical stone meet the following requirements: specific surface area ≥ 500 kg / m 3 The physical properties of the metakaolin satisfy: specific surface area ≥ 1000kg / m 3 .

[0037] In the embodiment of the present invention, the lightening agent is one or a mixture of poplar wood powder, rubber powder, and plastic powder; the physical properties of the poplar wood powder meet the following requirements: density ≤ 0.40 g / cm 3 , specific surface area ≥300kg / m 3 ; The physical properties of the rubber powder meet the following requirements: density ≤ 1.3 g / cm 3 , specific surface area ≥500kg / m 3 ; The physical properties of the plastic powder meet the following requirements: density ≤ 1.5 g / cm 3 , specific surface area ≥500kg / m 3 .

[0038] In the embodiment of the present invention, the early strength agent is a crystal nucleus type early strength agent, including one or more of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate. The particle size range of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate is between 50 and 100 nm.

[0039] In the embodiment of the present invention, the high temperature suspension stabilizer is a mixture of polyvinyl alcohol 1788, hectorite powder and dolomite powder; the physical properties of the polyvinyl alcohol 1788 meet the following requirements: purity ≥ 93.5%, specific surface area ≥ 200 kg / m 3 ; The physical properties of the hectorite powder meet the following requirements: specific surface area ≥ 350kg / m 3 ; The physical properties of the dolomite powder meet the following requirements: specific surface area ≥ 1000kg / m 3 .

[0040] In the embodiment of the present invention, the high-temperature fluid loss additive is G33S fluid loss additive.

[0041] In the embodiment of the present invention, the high temperature retarder is a random copolymer with a molecular weight between 20,000 and 40,000, which is prepared by free radical aqueous solution polymerization using 30 to 45 parts by weight of acrylamide, 30 to 40 parts by weight of maleic anhydride, 10 to 20 parts by weight of 3-allyloxy-2-hydroxy-1-propanesulfonate and 5 to 10 parts by weight of dimethyldiallylammonium chloride as monomers and 2 to 4 parts by weight of sodium bisulfite-ammonium persulfate as a composite initiator.

[0042] In the embodiment of the present invention, the preparation method of the high temperature retarder is as follows:

[0043] S1. At room temperature, add 30 to 45 parts of acrylamide, 30 to 40 parts of maleic anhydride, 10 to 20 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate, and 5 to 10 parts of dimethyldiallylammonium chloride to 100 parts of water, and fully dissolve and mix to obtain a first mixed solution;

[0044] S2. At room temperature, adjusting the pH of the first mixed solution to 7-8 using a sodium hydroxide solution having a mass concentration of 20% to obtain a second mixed solution;

[0045] S3. At room temperature, add 1 to 2 parts of sodium bisulfite to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a third mixed solution; add 1 to 2 parts of ammonium persulfate to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a fourth mixed solution;

[0046] S4, transferring the second mixed liquid to a reactor with a stirring device, introducing nitrogen to remove oxygen in the reactor and maintaining a nitrogen atmosphere, stirring and heating the second mixed liquid to 60° C. at 200 r / min, and then using a constant pressure funnel device to drop the third mixed liquid into the second mixed liquid at 10 drops / min, and after the addition is complete, also using a constant pressure funnel device to drop the fourth mixed liquid into the second mixed liquid at 10 drops / min, and after the addition is complete, to obtain a fifth mixed liquid;

[0047] S5. The fifth mixed liquid is kept at 60° C. for 3 hours, then naturally cooled to 45° C. and kept at 45° C. for 1-2 hours, and then taken out to obtain a ninth mixed liquid, which is the high-temperature retarder.

[0048] Example 1

[0049] As a preferred embodiment of the present invention, the high-temperature, large temperature difference, early-strength, low-density cementing slurry disclosed in this embodiment has a specific composition as shown in Table 1.

[0050] Table 1 Example 1 Cementing Slurry Composition Table

[0051]

[0052]

[0053] According to Table 1, weigh 100 parts of oil well cement, 35 parts of high temperature strength stabilizer, 10 parts of lightener, 0.2 parts of early strength agent, 0.3 parts of high temperature suspension stabilizer, 1 part of high temperature fluid loss reducer, 0.7 parts of high temperature retarder and 50 parts of water, and prepare high temperature, large temperature difference, early strength and low density cementing slurry 1# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0054] Example 2

[0055] As a preferred embodiment of the present invention, the high-temperature, large temperature difference, early-strength, low-density cementing slurry disclosed in this embodiment has a specific composition as shown in Table 2.

[0056] Table 2 Composition of cement slurry in Example 2

[0057] Component name Mass parts / parts Oil well cement 100 High temperature strength stabilizer 30 Lightening Agent 15 Early strength agent 0.3 High temperature suspension stabilizer 0.4 High temperature fluid loss additive 2 High temperature retarder 0.6 water 55

[0058] According to Table 2, weigh 100 parts of oil well cement, 30 parts of high temperature strength stabilizer, 15 parts of lightener, 0.3 parts of early strength agent, 0.4 parts of high temperature suspension stabilizer, 2 parts of high temperature fluid loss reducer, 0.6 parts of high temperature retarder and 55 parts of water, and prepare high temperature, large temperature difference, early strength and low density cementing slurry 2# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0059] Example 3

[0060] As a preferred embodiment of the present invention, the high-temperature, large temperature difference, early-strength, low-density cementing slurry disclosed in this embodiment has a specific composition as shown in Table 3.

[0061] Table 3 Composition of cement slurry in Example 3

[0062] Component name Mass parts / parts Oil well cement 100 High temperature strength stabilizer 25 Lightening Agent 20 Early strength agent 0.4 High temperature suspension stabilizer 0.5 High temperature fluid loss additive 3 High temperature retarder 0.5 water 60

[0063] According to Table 3, weigh 100 parts of oil well cement, 25 parts of high temperature strength stabilizer, 20 parts of lightener, 0.4 parts of early strength agent, 0.5 parts of high temperature suspension stabilizer, 3 parts of high temperature fluid loss reducer, 0.5 parts of high temperature retarder and 60 parts of water, and prepare high temperature, large temperature difference, early strength and low density cementing slurry 3# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0064] Example 4

[0065] As a preferred embodiment of the present invention, the high-temperature, large temperature difference, early-strength, low-density cementing slurry disclosed in this embodiment has a specific composition as shown in Table 4.

[0066] Table 4 Example 4 Cementing Slurry Composition Table

[0067] Component name Mass parts / parts Oil well cement 100 High temperature strength stabilizer 20 Lightening Agent 25 Early strength agent 0.5 High temperature suspension stabilizer 0.6 High temperature fluid loss additive 4 High temperature retarder 0.4 water 65

[0068] According to Table 4, weigh 100 parts of oil well cement, 20 parts of high temperature strength stabilizer, 25 parts of lightener, 0.5 parts of early strength agent, 0.6 parts of high temperature suspension stabilizer, 4 parts of high temperature fluid loss reducer, 0.4 parts of high temperature retarder and 65 parts of water, and prepare high temperature, large temperature difference, early strength and low density cementing slurry 4# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0069] Example 5

[0070] As a preferred embodiment of the present invention, the high-temperature, large temperature difference, early-strength, low-density cementing slurry disclosed in this embodiment has a specific composition as shown in Table 5.

[0071] Table 5 Example 5 Cementing Slurry Composition Table

[0072] Component name Mass parts / parts Oil well cement 100 High temperature strength stabilizer 15 Lightening Agent 30 Early strength agent 0.6 High temperature suspension stabilizer 0.7 High temperature fluid loss additive 5 High temperature retarder 0.3 water 70

[0073] According to Table 5, weigh 100 parts of oil well cement, 15 parts of high temperature strength stabilizer, 30 parts of lightener, 0.6 parts of early strength agent, 0.7 parts of high temperature suspension stabilizer, 5 parts of high temperature fluid loss reducer, 0.3 parts of high temperature retarder and 70 parts of water, and prepare high temperature, large temperature difference, early strength and low density cementing slurry 5# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0074] Comparative Example 1

[0075] The specific composition of the high-temperature, large-temperature-difference, low-density cementing slurry of this comparative example is shown in Table 6.

[0076] Table 6 Comparative Example 1 Cementing Slurry Composition

[0077]

[0078]

[0079] In this comparative example, the oil well cement is Grade G oil well cement, and its chemical requirements and physical properties meet the API specifications and the national standard "GB / T 10238-2015 Oil Well Cement".

[0080] In this comparative example, the high temperature strength stabilizer is quartz sand, and its chemical composition satisfies: SiO2 ≥ 98wt%, and its physical properties satisfy: specific surface area ≥ 250kg / m 2 .

[0081] In this comparative example, the lightening agent is hollow microspheres for oil well cement, and its physical properties meet the following requirements: purity ≥ 97%, density 0.3 g / cm3 , particle size is between 10-120μm, mesh size is 300 mesh, and floating rate is >90%.

[0082] In this comparative example, the early strength agent is a common early strength agent for oil well cement on the market, and the main components of this type of early strength agent are nanomaterials, inorganic salts and other materials.

[0083] In this comparative example, the high temperature suspension stabilizer is a common suspension stabilizer for oil well cement on the market, and the main components of this type of high temperature suspension stabilizer are high molecular polymer and clay.

[0084] In this comparative example, the high-temperature fluid loss reducer is a high-temperature fluid loss reducer commonly used in oil well cement on the market, and this type of fluid loss reducer is polymerized and modified by AMPS (2-acrylamide-2-methylpropanesulfonic acid), acrylamide, polyhydroxycarboxylic acid, and the like.

[0085] In this comparative example, the high temperature retarder is a high temperature retarder commonly used in oil well cement on the market, and this type of retarder is polymerized from AMPS, acrylic acid, and a high temperature resistant unsaturated monomer.

[0086] According to Table 6, weigh 100 parts of oil well cement, 35 parts of high temperature strength stabilizer, 10 parts of lightener, 0.2 parts of early strength agent, 0.3 parts of high temperature suspension stabilizer, 1 part of high temperature fluid loss reducer, 0.7 parts of high temperature retarder and 50 parts of water, and prepare high temperature, large temperature difference and low density cementing slurry 1# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0087] Comparative Example 2

[0088] The specific composition of the high-temperature, large-temperature-difference, low-density cementing slurry of this comparative example is shown in Table 7.

[0089] Table 7 Comparative Example 2 Cementing Slurry Composition Table

[0090]

[0091]

[0092] In this comparative example, the oil well cement is Grade G oil well cement, and its chemical requirements and physical properties meet the API specifications and the national standard "GB / T 10238-2015 Oil Well Cement".

[0093] In this comparative example, the high temperature strength stabilizer is quartz sand, and its chemical composition satisfies: SiO2 ≥ 98wt%, and its physical properties satisfy: specific surface area ≥ 250kg / m 2 .

[0094] In this comparative example, the lightening agent is hollow microspheres for oil well cement, and its physical properties meet the following requirements: purity ≥ 97%, density 0.3 g / cm3 , particle size is between 10-120μm, mesh size is 300 mesh, and floating rate is >90%.

[0095] In this comparative example, the early strength agent is a common early strength agent for oil well cement on the market, and the main components of this type of early strength agent are nanomaterials, inorganic salts and other materials.

[0096] In this comparative example, the high temperature suspension stabilizer is a common suspension stabilizer for oil well cement on the market, and the main components of this type of high temperature suspension stabilizer are high molecular polymer and clay.

[0097] In this comparative example, the high-temperature fluid loss reducer is a high-temperature fluid loss reducer commonly used in oil well cement on the market, and this type of fluid loss reducer is polymerized and modified by AMPS (2-acrylamide-2-methylpropanesulfonic acid), acrylamide, polyhydroxycarboxylic acid, and the like.

[0098] In this comparative example, the high temperature retarder is a high temperature retarder commonly used in oil well cement on the market, and this type of retarder is polymerized from AMPS, acrylic acid, and a high temperature resistant unsaturated monomer.

[0099] According to Table 7, weigh 100 parts of oil well cement, 25 parts of high temperature strength stabilizer, 20 parts of lightener, 0.4 parts of early strength agent, 0.5 parts of high temperature suspension stabilizer, 3 parts of high temperature fluid loss reducer, 0.5 parts of high temperature retarder and 60 parts of water, and prepare high temperature, large temperature difference and low density cementing slurry 2# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0100] Comparative Example 3

[0101] The specific composition of the high-temperature, large-temperature-difference, low-density cementing slurry of this comparative example is shown in Table 8.

[0102] Table 8 Comparative Example 3 Cementing Slurry Composition Table

[0103] Component name Mass parts / parts Oil well cement 100 High temperature strength stabilizer 15 Lightening Agent 30 Early strength agent 0.6 High temperature suspension stabilizer 0.7 High temperature fluid loss additive 5 High temperature retarder 0.3 water 70

[0104] In this comparative example, the oil well cement is Grade G oil well cement, and its chemical requirements and physical properties meet the API specifications and the national standard "GB / T 10238-2015 Oil Well Cement".

[0105] In this comparative example, the high temperature strength stabilizer is quartz sand, and its chemical composition satisfies: SiO2 ≥ 98wt%, and its physical properties satisfy: specific surface area ≥ 250kg / m 2 .

[0106] In this comparative example, the lightening agent is hollow microspheres for oil well cement, and its physical properties meet the following requirements: purity ≥ 97%, density 0.3 g / cm 3 , particle size is between 10-120μm, mesh size is 300 mesh, and floating rate is >90%.

[0107] In this comparative example, the early strength agent is a common early strength agent for oil well cement on the market, and the main components of this type of early strength agent are nanomaterials, inorganic salts and other materials.

[0108] In this comparative example, the high temperature suspension stabilizer is a common suspension stabilizer for oil well cement on the market, and the main components of this type of high temperature suspension stabilizer are high molecular polymer and clay.

[0109] In this comparative example, the high-temperature fluid loss reducer is a high-temperature fluid loss reducer commonly used in oil well cement on the market, and this type of fluid loss reducer is polymerized and modified by AMPS (2-acrylamide-2-methylpropanesulfonic acid), acrylamide, polyhydroxycarboxylic acid, and the like.

[0110] In this comparative example, the high temperature retarder is a high temperature retarder commonly used in oil well cement on the market, and this type of retarder is polymerized from AMPS, acrylic acid, and a high temperature resistant unsaturated monomer.

[0111] According to Table 7, weigh 100 parts of oil well cement, 15 parts of high temperature strength stabilizer, 30 parts of lightener, 0.6 parts of early strength agent, 0.7 parts of high temperature suspension stabilizer, 5 parts of high temperature fluid loss reducer, 0.3 parts of high temperature retarder and 70 parts of water, and prepare high temperature, large temperature difference and low density cementing slurry 3# in accordance with GB / T19139-2012 Test Method for Oil Well Cement.

[0112] Test Case

[0113] The engineering properties of cementing cement slurry in each comparative example and embodiment were tested according to "SY / T6544-2017 Performance Requirements for Oil Well Cement Slurry". The test method for the 60°C strength of the cement slurry top is: after the cementing cement slurry is heated to 150°C, it is kept for 30 minutes, the machine is shut down, and the temperature is naturally cooled to 60°C, then the thickening test slurry cup is taken out, and the thickened oil on the upper layer of the slurry cup is completely removed. The cement slurry is poured into the mold and placed in a 60°C water bath for curing, and the curing age is 24h and 48h. The test method for high temperature sedimentation stability is: according to the thickening test steps, the cementing cement slurry is heated to 150°C, kept for 30 minutes, the stirring is stopped, the temperature is cooled to 60°C, the thickening slurry cup is taken out, and it is left at room temperature for 2h, and the thickened oil on the upper layer of the slurry cup is removed. The cement slurry density in the upper and lower parts of the slurry cup is tested respectively, and the density difference between the upper and lower parts is calculated. The experimental results are shown in Table 9.

[0114] Table 9 Experimental results of examples and comparative examples

[0115]

[0116]

[0117] It can be seen from Table 9 that compared with the prior art, the high-temperature, large temperature difference, early-strength, low-density cementing slurry provided by the present invention has better comprehensive working performance. Specifically, the high-temperature, large temperature difference, early-strength, low-density cementing cement provided by the present invention has no free liquid and good rheological properties. The maximum API water loss at 150°C is only 62mL, and the high-temperature sedimentation stability at 150°C is less than 0.05g / cm 3 The high-temperature sedimentation stability of high-temperature, large temperature difference, low-density cementing slurry prepared by the existing technology at 150°C is greater than 0.05g / cm 3 This indicates that the high-temperature, large temperature difference, early-strength, low-density cementing cement of the present invention has excellent high-temperature sedimentation stability.

[0118] In addition, from Figure 1 to Figure 6 It can be seen that the high-temperature, large temperature difference, low-density cementing slurry prepared by the prior art is prone to abnormal gelation during the high-temperature thickening process, and the high-temperature thickening curve fluctuates significantly; while the high-temperature, large temperature difference, early-strength, low-density cementing slurry prepared by the present invention has better high-temperature thickening performance, and no abnormal gelation occurs during the high-temperature thickening process of the cement slurry, which is manifested as a stable high-temperature thickening curve with right-angle thickening. Furthermore, in the low-temperature area at the top of the long sealing section, the strength of the high-temperature, large temperature difference, low-density cementing slurry prepared by the prior art develops slowly, and even slow setting and super slow setting phenomena occur, while the high-temperature, large temperature difference, early-strength, low-density cementing slurry provided by the present invention develops faster in strength, has higher early strength, and the high-temperature strength does not decline within 14 days.

[0119] Finally, it should be noted that the above embodiments are only preferred embodiments of the present invention to illustrate the technical solutions of the present invention, rather than limiting them, and certainly not limiting the patent scope of the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention. In other words, any changes or modifications made to the main design concept and spirit of the present invention that have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention in other related technical fields is also included in the patent protection scope of the present invention.

Claims

1. A high temperature, large temperature difference, early strength, low density cementing slurry, characterized in that: It includes the following components by mass: 100 parts of oil well cement; 15-35 parts of high temperature strength stabilizer; 10-30 parts of lightening agent; 0.2-0.6 parts of early strength agent; High temperature suspension stabilizer 0.3-0.7 parts; 1 to 5 parts of high temperature fluid loss reducer; High temperature retarder 0.3-0.7 parts; 50-70 parts of water.

2. The high-temperature, large-temperature-difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The oil well cement is a mixture of G-grade cement and D-grade cement. The main mineral composition of the oil well cement is as follows: C3S: 60-68wt%, C2S: 20-25wt%, C3A: 0-1wt%, C4AF: 12-14wt%; the physical properties of the oil well cement meet the following requirements: specific surface area ≥400m 2 / kg, SO3 content ≤3wt%.

3. The high-temperature, large temperature difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The high temperature strength stabilizer is a mixture of quartz sand, kyanite powder, medical stone and metakaolin; the physical properties of the quartz sand meet the following requirements: specific surface area ≥500kg / m 3 ; The physical properties of the kyanite powder meet the following requirements: specific surface area ≥ 500 kg / m 3 ; The physical properties of the medical stone meet the following requirements: specific surface area ≥ 500 kg / m 3 ; The physical properties of the metakaolin meet the following requirements: specific surface area ≥ 1000 kg / m 3 .

4. The high-temperature, large temperature difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The lightening agent is one or a mixture of poplar wood powder, rubber powder, and plastic powder; the physical properties of the poplar wood powder meet the following requirements: density ≤ 0.40 g / cm 3 , specific surface area ≥300kg / m 3 ; The physical properties of the rubber powder meet the following requirements: density ≤ 1.3 g / cm 3 , specific surface area ≥500kg / m 3 ; The physical properties of the plastic powder meet the following requirements: density ≤ 1.5 g / cm 3 , specific surface area ≥500kg / m 3 .

5. The high-temperature, large-temperature-difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The early strength agent is a crystal nucleus type early strength agent, including one or more of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate. The particle size range of nano calcium silicate hydrate particles, nano calcium silicate, nano silicon dioxide, and nano calcium carbonate is between 50 and 100 nm.

6. The high-temperature, large temperature difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The high temperature suspension stabilizer is a mixture of polyvinyl alcohol 1788, hectorite powder and dolomite powder; the physical properties of the polyvinyl alcohol 1788 meet the following requirements: purity ≥ 93.5%, specific surface area ≥ 200 kg / m 3 ; The physical properties of the hectorite powder meet the following requirements: specific surface area ≥ 350 kg / m 3 ; The physical properties of the dolomite powder meet the following requirements: specific surface area ≥ 1000 kg / m 3 .

7. The high-temperature, large temperature difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The high temperature fluid loss agent is G33S fluid loss agent.

8. The high-temperature, large temperature difference, early-strength, low-density cementing slurry according to claim 1, characterized in that: The high-temperature retarder is a random copolymer with a molecular weight between 20,000 and 40,000, which is prepared by free radical aqueous solution polymerization using 30 to 45 parts by weight of acrylamide, 30 to 40 parts by weight of maleic anhydride, 10 to 20 parts by weight of 3-allyloxy-2-hydroxy-1-propanesulfonate and 5 to 10 parts by weight of dimethyldiallylammonium chloride as monomers and 2 to 4 parts by weight of sodium bisulfite-ammonium persulfate as a composite initiator.

9. The high-temperature, large-temperature-difference, early-strength, low-density cementing slurry according to claim 8, characterized in that: The preparation method of the high temperature retarder is as follows: S1. At room temperature, add 30 to 45 parts of acrylamide, 30 to 40 parts of maleic anhydride, 10 to 20 parts of 3-allyloxy-2-hydroxy-1-propanesulfonate, and 5 to 10 parts of dimethyldiallylammonium chloride to 100 parts of water, and fully dissolve and mix to obtain a first mixed solution; S2. At room temperature, adjusting the pH of the first mixed solution to 7-8 using a sodium hydroxide solution having a mass concentration of 20% to obtain a second mixed solution; S3. At room temperature, add 1 to 2 parts of sodium bisulfite to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a third mixed solution; add 1 to 2 parts of ammonium persulfate to 23 to 24 parts of water by mass, fully dissolve and mix to obtain a fourth mixed solution; S4, transferring the second mixed liquid to a reactor with a stirring device, introducing nitrogen to remove oxygen in the reactor and maintaining a nitrogen atmosphere, stirring and heating the second mixed liquid to 60° C., and then using a constant pressure funnel device to drop the third mixed liquid into the second mixed liquid, and after the dropwise addition is completed, also using a constant pressure funnel device to drop the fourth mixed liquid into the second mixed liquid, and after the dropwise addition is completed, a fifth mixed liquid is obtained; preferably, the stirring speed during stirring and heating is 200 r / min, and the dropping speeds of the third mixed liquid and the fourth mixed liquid are both 10 drops / min; S5. The fifth mixed liquid is kept at 60° C. for 3 hours, then naturally cooled to 45° C. and kept at 45° C. for 1-2 hours, and then taken out to obtain a ninth mixed liquid, which is the high-temperature retarder.

10. The method for preparing a high-temperature, large temperature difference, early-strength, low-density cementing slurry according to any one of claims 1 to 9, characterized in that:The method comprises the following operations: weighing 100 parts of oil well cement, 10 to 35 parts of high temperature strength stabilizer, 10 to 30 parts of lightener, 0.2 to 0.6 parts of early strength agent, 0.3 to 0.7 parts of high temperature suspension stabilizer, 1 to 5 parts of high temperature fluid loss reducer, 0.3 to 0.7 parts of high temperature retarder and 50 to 70 parts of water by mass, and preparing the high temperature, large temperature difference early strength and low density cementing cement slurry according to GB / T19139-2012 Test Method for Oil Well Cement.

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