Low-density geopolymer cementing fluid

Abstract

The invention provides a low-density geopolymer cementing fluid. The low-density geopolymer cementing fluid comprises a cementing material, an activating agent, a retarder, a dispersing agent, a fluid loss agent, an anti-settling agent and water. According to the cementing fluid, the density of the cementing fluid is adjusted, the water loss performance of a geopolymer system is improved, and the cementing fluid has excellent compressive strength which can be higher than 20 MPa; the settling stability is excellent, and the cement stone density difference can be lower than 0.01 g / cm < 3 >; an excellent dispersing agent is introduced into the well cementing fluid, on-site pump injection is facilitated, the well cementing fluid has excellent rheological properties, and the reading of the well cementing fluid at 300 rpm in a six-speed rotational viscometer is lower than 100; the fluid loss agent is introduced into the cementing fluid, the fluid loss agent with low viscosity can ensure that the cementing fluid has good fluidity, and the water loss performance of the geopolymer cementing fluid can be effectively controlled.

Description

Technical Field

[0001] This invention relates to the field of green cementing technology for oil and gas wells, and more specifically, to a low-density geopolymer cementing fluid. Background Technology

[0002] Cementing quality is crucial to the safe and long-term production of oil and gas wells. Cementing operations utilize large quantities of well cement to seal the annulus between the casing and the wellbore, typically using hundreds or even thousands of tons of cement per well. Cement slurry is usually formulated from G-grade or H-grade cement (both silicate cements). Although traditional silicate well cement is widely used in cementing, it still has certain shortcomings: (1) The cement industry is a major carbon emitter, and the long-term and large-scale use of silicate cement has put enormous pressure on the national carbon emission reduction strategy. The production of silicate cement releases a large amount of CO2. Taking into account the energy consumption during cement production and the decomposition of limestone, the raw material for cement, approximately 0.668 tons of CO2 will be released for every ton of cement produced. According to reports, in 2020, my country's cement industry emitted 1.23 billion tons of carbon, accounting for approximately 12.4% of the country's total carbon emissions. Therefore, cement production has put enormous pressure on the national carbon emission reduction strategy and has also become an important breakthrough point for the national carbon emission reduction strategy. At present, the main directions of carbon emission reduction measures in the cement industry are to limit production capacity, reduce energy consumption, and carbon capture. However, in terms of carbon capture alone, the domestic cement industry has only built a production line with a carbon capture capacity of 50,000 tons / year, and the carbon emission reduction pressure on the cement industry is still very high.

[0003] (2) Traditional silicate oil well cement exhibits significant batch-to-batch performance variations and numerous engineering performance defects, posing substantial challenges to on-site cementing operations. ① Traditional silicate cement is primarily composed of tricalcium silicate, dicalcium silicate, tricalcium aluminate, tetracalcium aluminoferrite, gypsum, and free calcium oxide. Due to differences in raw materials and production processes, cement performance, particularly the thickening time of cement slurry, varies considerably between different manufacturers or even between different batches from the same manufacturer. ② Traditional silicate cement has poor adaptability to large temperature differences. While the cement slurry sets quickly at high temperatures at the bottom of the well, it fails to solidify for extended periods at low temperatures at the top of long-sealed cementing sections, impacting construction safety and progress. ③ In certain temperature ranges (e.g., 70-90℃ or 130-140℃), traditional silicate cement exhibits an abnormal phenomenon where the cement slurry sets at lower temperatures shorter than at higher temperatures, exacerbating the "weight loss" of the cement slurry during cementing and affecting cementing safety. ④ Traditional silicate cement hydration products are mainly high-calcium minerals such as calcium hydroxide and CSH gel, which have poor resistance to CO2 corrosion and are difficult to apply to cementing operations in carbon-buried wells. The above problems pose a significant challenge to the formulation of cement slurry properties on site.

[0004] To address the carbon emissions associated with cement production, both domestic and international efforts are actively exploring and researching alternatives to silicate cement. These alternatives align with the low-carbon emission characteristics of national carbon reduction strategies and are more conducive to promoting the widespread application of geopolymers in oil and gas well cementing. Summary of the Invention

[0005] In view of this, this invention proposes a low-density geopolymer cementing fluid to address existing problems. The studied geopolymer material possesses advantages such as high strength, low carbon emissions (approximately 1 / 6 of cement's carbon emissions), and environmental friendliness, and is considered the most promising "cement alternative." Research shows that due to significant differences in its bonding properties and mineral composition compared to silicate cement, it exhibits excellent resistance to carbon dioxide and salt corrosion, low permeability, resistance to drilling fluid contamination, and self-healing capabilities, making it highly suitable for cementing wells with CO2 storage, wells completed with oil-based drilling fluids, and wells requiring high annular sealing capabilities.

[0006] The present invention proposes a low-density geological polymer cementing fluid, comprising the following components: cementing material, activator, retarder, dispersant, fluid loss reducer, anti-settling agent, and water.

[0007] Further, the weight parts of each of the above-mentioned components are as follows: cementitious material, 100 parts; activator, 19-20 parts; retarder, 2-3 parts; dispersant, 1.8-2.5 parts; water loss reducer, 4-7 parts; anti-settling agent, 0.7-1.4 parts; water, 35 parts.

[0008] Furthermore, the cementing material includes fly ash, hollow microspheres, slag, and microsilica.

[0009] Specifically, the density of the cementing fluid was adjusted by adding hollow microspheres, and the water loss performance of the geopolymer system was improved by adding microsilica.

[0010] Furthermore, the activator includes sodium fluoride and calcium hydroxide.

[0011] Furthermore, the retarder is an organophosphate composite retarder BXR-201L.

[0012] Furthermore, the dispersant is an organic dispersant BCD-211L.

[0013] Specifically, the introduction of a dispersant facilitates on-site pumping, and the cementing fluid possesses excellent rheological properties, with a reading below 100 at 300 rpm on a six-speed rotary viscometer.

[0014] Furthermore, the water loss reducing agent is BCF-230L, which is prepared by copolymerization of various ethylene monomers.

[0015] Specifically, the introduction of a fluid loss control agent, a low-viscosity fluid loss control agent, can ensure that the cementing fluid has good fluidity and can effectively control the fluid loss performance of geopolymer cementing fluid.

[0016] Furthermore, the anti-settling agent is a suspending agent BCJ-300S obtained by combining inorganic and organic materials.

[0017] Specifically, by introducing an anti-settling agent, this cementing fluid exhibits excellent settling stability, with the density difference of the cement stone remaining below 0.01 g / cm³. 3 .

[0018] Furthermore, the density of the low-density geopolymer cementing fluid is in the range of 1.40 g / cm³. 3 -1.60g / cm 3 .

[0019] Furthermore, the thickening time of the low-density geopolymer cementing fluid is matched to the requirements of on-site cementing operations for oil and gas wells.

[0020] The low-density geopolymer cementing fluid provided by this invention has the following advantages: The density of the cementing fluid can be adjusted by adding hollow microspheres, and the addition of microsilica can also improve the water loss performance of the geopolymer system; the cementing fluid has excellent compressive strength, which can exceed 20 MPa; due to the introduction of an anti-settling agent, the cementing fluid has excellent settling stability, and the density difference of the cement stone can be less than 0.01 g / cm³. 3 The cementing fluid incorporates an excellent dispersant for convenient on-site pumping. It also possesses excellent rheological properties, with a reading below 100 at 300 rpm on a six-speed rotary viscometer. Furthermore, it incorporates a fluid loss reducer, whose low viscosity ensures good fluidity and effectively controls the fluid loss performance of the geopolymer cementing fluid. Attached Figure Description

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 Performance test tables of cementing fluids provided for comparative and exemplary embodiments of the present invention. Detailed Implementation

[0022] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] This invention discloses a low-density geopolymer cementing fluid designed to address existing problems. The studied geopolymer material possesses advantages such as high strength, low carbon emissions (approximately 1 / 6 that of cement), and environmental friendliness, making it considered a promising "cement substitute." Research indicates that due to significant differences in its bonding properties and mineral composition compared to silicate cement, it exhibits excellent resistance to carbon dioxide and salt corrosion, low permeability, resistance to drilling fluid contamination, and self-healing capabilities, making it highly suitable for cementing wells with CO2 storage, wells completed with oil-based drilling fluids, and wells requiring high annular sealing capabilities.

[0024] This low-density geological polymer cementing fluid comprises the following components: cementing material, activator, retarder, dispersant, fluid loss reducer, anti-settling agent, and water.

[0025] In one embodiment, the low-density geological polymer cementing fluid comprises the following components in parts by weight: cementing material, 100 parts; activator, 19-20 parts; retarder, 2-3 parts; dispersant, 1.8-2.5 parts; fluid loss reducer, 4-7 parts; anti-settling agent, 0.7-1.4 parts; and water, 35 parts.

[0026] In this embodiment, the cementing material includes fly ash, hollow microspheres, slag, and microsilica. The activator includes sodium fluoride and calcium hydroxide. The retarder is an organophosphate composite retarder BXR-201L. The dispersant is an organic dispersant BCD-211L. The fluid loss reducing agent is a fluid loss reducing agent BCF-230L prepared by copolymerization of various ethylene monomers. The anti-settling agent is a suspending agent BCJ-300S obtained by combining inorganic and organic materials. The density range of the aforementioned low-density geological polymer cementing fluid is 1.40 g / cm³. 3 -1.60g / cm 3 .

[0027] The thickening time of the low-density geopolymer cementing fluid disclosed in this embodiment matches the requirements of on-site cementing operations for oil and gas wells.

[0028] The performance of the low-density geopolymer cementing fluid disclosed in this invention was tested in conjunction with Examples 1-9 and Comparative Example 1: the cementing fluid was prepared according to the cementing test standard API RP10B, and the performance and compressive strength of the cementing fluid were measured.

[0029] Comparative Example 1 80 parts fly ash, 0 parts hollow microspheres, 20 parts slag, 0 parts microsilica, 2 parts retarder, 2.5 parts dispersant, 7 parts water loss reducer, 1 part anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0030] Example 1 40 parts fly ash, 35 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2 parts retarder, 2.5 parts dispersant, 7 parts water loss reducer, 0.9 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0031] Example 2 40 parts fly ash, 35 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2 parts retarder, 2.5 parts dispersant, 7 parts water loss reducer, 1.4 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0032] Example 3 40 parts fly ash, 35 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.5 parts retarder, 2.5 parts dispersant, 7 parts water loss reducer, 1.4 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0033] Example 4 50 parts fly ash, 25 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.3 parts retarder, 2 parts dispersant, 6 parts water loss reducer, 0.7 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0034] Example 5 50 parts fly ash, 25 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.3 parts retarder, 2 parts dispersant, 6 parts water loss reducer, 1.2 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0035] Example 6 50 parts fly ash, 25 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.8 parts retarder, 2 parts dispersant, 6 parts water loss reducer, 1.2 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0036] Example 7 65 parts fly ash, 10 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.5 parts retarder, 1.8 parts dispersant, 4.5 parts water loss reducer, 0.5 parts anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0037] Example 8 65 parts fly ash, 10 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 2.5 parts retarder, 1.8 parts dispersant, 4.5 parts water loss reducer, 1 part anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0038] Example 9 65 parts fly ash, 10 parts hollow microspheres, 20 parts slag, 5 parts microsilica, 3 parts retarder, 1.8 parts dispersant, 4.5 parts water loss reducer, 1 part anti-settling agent, 35 parts water, 9 parts calcium hydroxide, and 10.2 parts sodium fluoride.

[0039] The experimental results of Examples 1-9 and Comparative Example 1 are as follows, with reference to... Figure 1 ,according to Figure 1 In terms of strength, the strength of the geopolymer at 48 hours was lower than that of the comparative example because hollow microspheres were added in the examples, which reduced the density of the cementing fluid system. In Examples 3, 6 and 9, the amount of retarder added was relatively large, and the thickening time of the geopolymer was longer, resulting in a decrease in strength at 24 hours.

[0040] In summary, the low-density geopolymer cementing fluid provided by this invention has the following beneficial technical effects: the density of the cementing fluid is adjusted by adding hollow microspheres, and the addition of microsilica can also improve the water loss performance of the geopolymer system; the cementing fluid has excellent compressive strength, which can be higher than 20 MPa; due to the introduction of anti-settling agents, the cementing fluid has excellent settling stability, and the density difference of cement stone can be less than 0.01 g / cm³. 3 The cementing fluid incorporates an excellent dispersant for convenient on-site pumping. It also possesses excellent rheological properties, with a reading below 100 at 300 rpm on a six-speed rotary viscometer. Furthermore, it incorporates a fluid loss reducer, whose low viscosity ensures good fluidity and effectively controls the fluid loss performance of the geopolymer cementing fluid.

[0041] It should be noted that in the description of this invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc., which indicate the direction or positional relationship, are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and is not intended to indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0042] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A low-density geopolymer cementing fluid, characterized in that, It includes the following components: cementitious materials, activators, retarders, dispersants, water loss reducers, anti-settling agents, and water.

2. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The weight parts of each component are as follows: cementitious material, 100 parts; activator, 19-20 parts; retarder, 2-3 parts; dispersant, 1.8-2.5 parts; water loss reducer, 4-7 parts; anti-settling agent, 0.7-1.4 parts; water, 35 parts.

3. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The cementing material includes fly ash, hollow microspheres, slag, and microsilica.

4. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The activator includes sodium fluoride and calcium hydroxide.

5. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The retarder is an organophosphate composite retarder BXR-201L.

6. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The dispersant is an organic dispersant BCD-211L.

7. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The water loss reducing agent is BCF-230L, which is prepared by copolymerization of various ethylene monomers.

8. The low-density geopolymer cementing fluid according to claim 1, characterized in that, The anti-settling agent is a suspending agent BCJ-300S, which is a composite of inorganic and organic materials.

9. The low-density geopolymer cementing fluid according to any one of claims 1-8, characterized in that, The density range of the low-density geopolymer cementing fluid is 1.40 g / cm³. 3 -1.60g / cm 3 .

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