Cement paste for well cementation of coal-bed gas well as well as preparation and application of cement paste

Abstract

The invention discloses well cementation cement paste for a coal-bed gas well, which comprises the following components in parts by mass: 100 parts of oil well G-grade cement, 20-35 parts of oil well superfine cement, 20-40 parts of a lightening agent A, 15-20 parts of a lightening agent B, 8-10 parts of a lightening agent C, 0.5-1.5 parts of a stabilizer, 2-3 parts of a fluid loss agent, 2-4 parts of a low-temperature coagulant and 3-5 parts of a dispersing agent, and 0.5-1 part by mass of a defoaming agent. The density of the cement paste is 1.10-1.30 g / cm < 3 >, the 48h compressive strength (taking 1.30 g / cm < 3 > as an example) is 11.4 Mpa, and the cement paste adapts to the low-temperature environment of 23-45 DEG C and can meet the cementing operation of shallow low-rank coal.

Description

Technical Field

[0001] The invention relates to cement slurry for coal bed gas wells and its preparation and application. Background Art

[0002] In the development of coalbed methane, different mining plans need to be implemented in view of the different grades and burial depths of coal seams. In some areas, low-rank coalbed methane resources are abundant, coal seams are extremely thick, coal body structure is mainly primary structure, cleat fractures are developed, coal quality is loose and broken, permeability is good, and the formation pressure bearing capacity is poor. Coal rock is easily contaminated during drilling and is complex and frequent. Coal seams have both leakage points and water inflow points. The coal seams in some areas are shallowly buried, within 600m, and the formation temperature is generally between 23 and 45℃, which will also make the later cementing operations more difficult. The selection of cementing cement slurry has put forward requirements, and it is necessary to develop a cement slurry with high compressive strength and reduced density in a low temperature environment. Summary of the invention

[0003] In order to enrich the types of cementing slurries and meet the needs of coal seam mining under different geological conditions, the present invention is made, which is particularly suitable for shallow low-rank coal.

[0004] In view of the coal seam characteristics in some areas with a depth of less than 600m and a formation temperature of 23-45°C, the inventor used existing cement slurry for cementing operations and found that the conventional density of 1.65-1.95g / cm 3 Although cement slurry can overcome the influence of low temperature, its high density is easy to leak out of the formation, and the leakage return height is not enough to meet the design requirements, resulting in serious pollution of the reservoir by cement slurry leakage. 3 Ultra-low density cement slurry can solve the problem of leakage, but it needs a relatively high temperature (greater than 60°C) to achieve the expected compressive strength. At low temperatures, the compressive strength of cement stone develops slowly and the cementing quality is difficult to guarantee. It is not suitable for the low temperature environment of coalbed methane cementing.

[0005] As one aspect of the present invention, it relates to a cement slurry for cementing a coalbed methane well, the cement slurry comprising: 100 parts by mass of oil well G grade cement, 20-35 parts by mass of oil well superfine cement, 20-40 parts by mass of lightener A, 15-20 parts by mass of lightener B, 8-10 parts by mass of lightener C, 0.5-1.5 parts by mass of stabilizer, 2-3 parts by mass of fluid loss reducer, 2-4 parts by mass of low-temperature accelerator, 3-5 parts by mass of dispersant, and 0.5-1 parts by mass of defoamer.

[0006] In a specific embodiment, the average particle size of the oil well G grade cement is 20-25 um.

[0007] In a specific embodiment, the average particle size of the oil well ultrafine cement is 10-15 um.

[0008] In a specific embodiment, the lightening agent A has an average particle size of 50-70 um, a compressive strength of 4000 psi, and a density of 0.39-0.43 g / cm3.

[0009] In a specific embodiment, the lightening agent B comprises microspheres with an average particle size of 100-150 um, a compressive strength of 7000 psi, and a density of 0.70-0.72 g / cm3;

[0010] In a specific embodiment, the lightening agent C comprises microsilicon with an average particle size of 1-2 um.

[0011] In a specific embodiment, the low-temperature coagulant is CA903S.

[0012] In a specific embodiment, the fluid loss additive is DRF-120L, the dispersant is DRS-1S, the defoamer is DRX-1L, and the stabilizer is DRK-3S.

[0013] In a specific embodiment, the cement slurry for coalbed methane well cementing further comprises 100-120 parts by weight of water.

[0014] As another aspect of the present invention, it relates to the application of the above-mentioned cement slurry for coalbed methane well cementing in the cementing of coalbed methane wells.

[0015] As another aspect of the present invention, it relates to a method for preparing the above-mentioned cement slurry for cementing a coalbed methane well, comprising:

[0016] Add lightening agent micro beads, lightening agent floating beads, lightening agent micro silicon,

[0017] Oil well G grade cement and superfine cement are dry mixed, and then the dry mixed powder is added into water for stirring, and dispersant, stabilizer, fluid loss reducer, low temperature accelerator and defoamer are added respectively for stirring.

[0018] As another aspect of the present invention, it relates to a coalbed methane well, which is cemented using the above-mentioned cement slurry for cementing a coalbed methane well.

[0019] The lightening agent used in the embodiment of the present invention is Y4000 microspheres with moderate compressive strength produced by Maanshan Mining Research Institute of China Steel Group, with a density of 0.39-0.43 g / cm 3 , average particle size 60um; floating beads are produced by 3M Company in the United States, with a density of 0.70-0.72g / cm 3 , average particle size 120um; microsilicon is produced by Tianjin PetroChina Boxing Company, density 2.50-2.60g / cm 3, with an average particle size of 1 um. In the preparation method provided by the present invention, the stirring rate is 2000-4000 rpm; the preparation environment temperature is 20-30° C.; and the feeding time interval is 10-20 minutes.

[0020] The cement slurry for coalbed methane wells provided by the present invention has the characteristics of low temperature and low density, and the strength can meet the requirements of cementing quality and subsequent perforation and fracturing wellbore sealing, which is helpful to achieve low-cost and efficient development of low-rank coal. DETAILED DESCRIPTION

[0021] The inventor conducted experiments based on the following prior art, and the experimental results did not meet the inventor's expectations:

[0022] The inventors prepared cement slurry based on the literature such as Sun Fuquan, Hou Wei, Jin Jianzhou, Gao Yonghui. Design and research of ultra-low density cement slurry system [J]. Drilling Fluids and Completion Fluids. 2007(03); Luo Yang, Chen Dajun, Xu Guili, Wan Wei, Chen An. Experimental study on high-strength ultra-low density cement slurry system [J]. Petroleum Drilling Technology. 2009(05); Gong Yingjie, Li Hongjun, Zhang Heng, Nie Haifeng, Wang Guihong, Yin Wei. Design method of particle size distribution of low-density cement slurry filling reinforcement material [J]. Journal of Petroleum and Natural Gas. 2010(01); Liu Qingwang, Chen Jinqiu. Research on fly ash composite low-density cement slurry system [J]. Science Technology and Engineering. 2010(21); Ma Zhe, Pang Hao, Yang Yuanlong, Xu Yuliang. Review of research progress of chemical grouting materials [J]. Guangzhou Chemistry. 2014, 39(01), etc. The experimental results did not meet the inventors' expectations.

[0023] The inventor referred to CN201710040782.5 and prepared a low-density cement slurry using active lightening materials, but the test results did not meet the inventor's expectations.

[0024] The inventors prepared a low-density and high-strength cement slurry with reference to CN201510329212.9, but the test results did not meet the inventors' expectations.

[0025] The inventors prepared a high-strength, low-density cement slurry with reference to CN201510296713.1, but the test results did not meet the inventors' expectations.

[0026] The inventors prepared a low-density cement slurry system with reference to CN201310195457.8, but the test results did not meet the inventors' expectations.

[0027] The inventors prepared a low-density, early-strength, slightly expansive cement slurry with reference to CN201410432172.6, but the test results did not meet the inventors' expectations.

[0028] The inventor prepared a low-density cement slurry with reference to CN201210553021.7, but the test results did not meet the inventor's expectations.

[0029] The inventor applied the close packing theory and combined it with the indoor stacking porosity experiment to obtain a density of 1.10-1.30 g / cm 3 Low temperature ultra-low density cement slurry system. The 48h compressive strength of the system (1.30g / cm 3 For example) 11.4Mpa, which can adapt to the low temperature environment of 23-45℃ and meet the cementing operation of shallow low-rank coal.

[0030] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0031] The embodiment of the present invention provides a low-temperature and low-density cementing slurry system for coalbed methane wells, wherein the cement slurry comprises oil well G-grade cement, oil well ultrafine cement, lightener A, lightener B, lightener C, stabilizer, fluid loss reducer, low-temperature coagulant, dispersant, defoamer and water; and based on 100 parts by weight of oil well G-grade cement, the oil well ultrafine cement comprises 20-35 parts by weight, the lightener A comprises 20-40 parts by weight, the lightener B comprises 15-20 parts by weight, the lightener C comprises 8-10 parts by weight, the stabilizer comprises 0.5-1.5 parts by weight, the fluid loss reducer comprises 2-3 parts by weight, the low-temperature coagulant comprises 2-4 parts by weight, the dispersant comprises 3-5 parts by weight, the defoamer comprises 0.5-1 parts by weight, and the water comprises 90-110 parts by weight.

[0032] The average particle size of the oil well G grade cement is 20-25um, and the average particle size of the oil well superfine cement is 10-15um.

[0033] The low-temperature coagulant used in the embodiment of the present invention is CA903S, and its applicable temperature range is 20-50°C.

[0034] The fluid loss additive used in the embodiment of the present invention is DRF-120L, the dispersant is DRS-1S, the defoamer is DRX-1L, and the stabilizer is DRK-3S, all of which are products produced and sold by China National Petroleum Corporation Engineering Technology Research Institute Co., Ltd.

[0035] The density of the cement slurry prepared in the embodiment of the present invention is 1.10-1.30 g / cm 3 .

[0036] Example 1

[0037] The low-temperature and low-density cementing slurry system provided in this embodiment has a formula composition as follows: based on 100 parts by weight of oil well G grade cement, 25 parts by weight of oil well superfine cement, 40 parts by weight of lightener A, 30 parts by weight of lightener B, 8 parts by weight of lightener C, 1.5 parts by weight of the stabilizer, 3 parts by weight of the fluid loss reducer, 4 parts by weight of the low-temperature coagulant, 3 parts by weight of the dispersant, 0.5 parts by weight of the defoamer, and 120 parts by weight of water.

[0038] The average particle size of the oil well G grade cement is 20 um, and the average particle size of the oil well superfine cement is 10 um.

[0039] According to the above ratio, configure as follows:

[0040] (1) 100 g of oil well G grade cement and 25 g of ultrafine cement were dry mixed and stirred for 10 minutes at a stirring rate of 200 rpm;

[0041] (2) Add 40 g of lightener A, 30 g of lightener B, and 8 g of lightener C to the mixture in the previous step, dry mix, and stir for 10 minutes at a stirring rate of 200 rpm;

[0042] (3) Add 120 g of water to the mixture in the previous step and stir at 4000 rpm for 10 min;

[0043] (4) Add 3 g of dispersant, 0.5 g of stabilizer, 3 g of fluid loss reducer, 3 g of low-temperature coagulant, and 0.5 g of defoamer to the liquid in the previous step, and stir for 20 minutes at a stirring rate of 4000 rpm;

[0044] You can get 1.10g / cm 3 Low temperature and ultra-low density cementing slurry system.

[0045] Example 2

[0046] The low-temperature and low-density cementing slurry system provided in this embodiment has a formula composition: based on 100 parts by weight of oil well G grade cement, 30 parts by weight of oil well superfine cement, 25 parts by weight of lightener A, 15 parts by weight of lightener B, 8 parts by weight of lightener C, 1 part by weight of the stabilizer, 2 parts by weight of the fluid loss reducer, 3 parts by weight of the low-temperature accelerator, 4 parts by weight of the dispersant, 1 part by weight of the defoamer, and 110 parts of water.

[0047] According to the above ratio, configure as follows:

[0048] (1) 100 g of oil well G grade cement and 30 g of ultrafine cement were dry mixed and stirred for 10 minutes at a stirring rate of 200 rpm;

[0049] (2) Add 25 g of lightener A, 15 g of lightener B, and 8 g of lightener C to the mixture in the previous step, dry mix, and stir for 10 minutes at a stirring rate of 200 rpm;

[0050] (3) Add 110 g of water to the mixture in the previous step and stir at 4000 rpm for 10 min;

[0051] (4) Add 3 g of dispersant, 0.5 g of stabilizer, 3 g of fluid loss reducer, 3 g of low-temperature coagulant, and 0.5 g of defoamer to the liquid in the previous step, and stir for 20 minutes at a stirring rate of 4000 rpm;

[0052] You can get 1.18g / cm 3 Low temperature and ultra-low density cementing slurry system.

[0053] Example 3

[0054] The low-temperature and low-density cementing slurry system provided in this embodiment has a formula composition: based on 100 parts by weight of oil well G grade cement, 35 parts by weight of oil well superfine cement, 20 parts by weight of lightener A, 15 parts by weight of lightener B, 10 parts by weight of lightener C, 0.5 parts by weight of the stabilizer, 2 parts by weight of the fluid loss reducer, 2 parts by weight of the low-temperature coagulant, 5 parts by weight of the dispersant, 1 part by weight of the defoamer, and 100 parts of water.

[0055] According to the above ratio, configure as follows:

[0056] (1) 100 g of oil well G grade cement and 35 g of ultrafine cement were dry mixed and stirred for 10 minutes at a stirring rate of 200 rpm;

[0057] (2) Add 20 g of lightener A, 15 g of lightener B, and 10 g of lightener C to the mixture in the previous step, dry mix, and stir for 10 minutes at a stirring rate of 200 rpm;

[0058] (3) Add 100 g of water to the mixture in the previous step and stir at 4000 rpm for 10 min;

[0059] (4) Add 3 g of dispersant, 0.5 g of stabilizer, 3 g of fluid loss reducer, 3 g of low-temperature coagulant, and 0.5 g of defoamer to the liquid in the previous step, and stir for 20 minutes at a stirring rate of 4000 rpm;

[0060] You can get 1.30g / cm 3 Low temperature and ultra-low density cementing slurry system.

[0061] Note: After adding the lightening material, the high-speed stirring speed is 4000rpm, the overall viscosity of the cement slurry increases, and the stirring time is long, the cement slurry will heat up quickly, causing the liquid phase in the cement slurry to evaporate too quickly. Therefore, during the preparation process, pay attention to controlling the stirring time to ensure the accuracy of the experiment.

[0062] Example 4

[0063] The above examples 1, 2, and 3 can obtain densities of 1.10 g / cm 3 , 1.18g / cm 3 , 1.3g / cm 3 The low-temperature ultra-low-density cementing slurry system has performance indicators as shown in the following table:

[0064] (1) Compressive strength test

[0065]

[0066] (2) Sedimentation stability evaluation

[0067]

[0068]

[0069] (3) Rheological evaluation

[0070]

[0071] (4) Evaluation of thickening time

[0072]

[0073] Based on the above results, it can be seen that the low-density cement slurry of 1.10-1.30g / cm3 formed by the present invention is suitable for the development of shallow low-rank coalbed methane with a formation temperature of less than 50°C. The compressive strength, sedimentation stability, rheology and thickening time all show good performance and can meet the cementing construction and cementing quality of production casing.

[0074] The above embodiments describe the present invention in detail, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A cement slurry for cementing a coalbed methane well, characterized in that: The cement slurry comprises: 100 parts by weight of oil well G grade cement, 20-35 parts by weight of oil well superfine cement, 20-40 parts by weight of lightener A, 15-20 parts by weight of lightener B, 8-10 parts by weight of lightener C, 0.5-1.5 parts by weight of stabilizer, 2-3 parts by weight of fluid loss reducer, 2-4 parts by weight of low temperature accelerator, 3-5 parts by weight of dispersant, and 0.5-1 parts by weight of defoamer.

2. The cement slurry for cementing coalbed methane wells according to claim 1, characterized in that: The average particle size of the oil well G grade cement is 20-25 um.

3. The cement slurry for cementing coalbed methane wells according to claim 1, characterized in that: The average particle size of the oil well ultrafine cement is 10-15 um.

4. The cement slurry for cementing coalbed methane wells according to claim 1, characterized in that: The lightening agent A is a micro-bead material with an average particle size of 50-70um, a compressive strength of 4000psi, and a density of 0.39-0.43g / cm 3 ; Lightening agent B is a floating bead material with an average particle size of 100-150um, a compressive strength of 7000psi, and a density of 0.70-0.72g / cm 3 ; Lightening agent C is a micro-silicon material, the main component of which is silicon dioxide, with an average particle size of 1-2um.

5. The cement slurry for cementing coalbed methane wells according to claim 1, characterized in that: The low-temperature coagulant is calcium chloride, sodium chloride or formamide.

6. The cement slurry for cementing coalbed methane wells according to claim 1, characterized in that: The fluid loss reducer is DRF-120L, the dispersant is DRS-1S, the defoamer is DRX-1L, and the stabilizer is DRK-3S.

7. The cement slurry for cementing a coalbed methane well according to any one of claims 1 to 6, characterized in that: Contains 100-120 parts by mass of water.

8. Use of the cement slurry for coalbed methane well cementing as described in any one of claims 1 to 7 in cementing of coalbed methane wells.

9. The method for preparing the cement slurry for coalbed methane well according to claim 8, characterized in that: include: Firstly, the lightening agent floating beads, lightening agent micro beads, lightening agent micro silicon, oil well G grade cement, superfine cement, dispersant, stabilizer, fluid loss reducer, low temperature accelerator and defoamer are dry mixed, and then the dry mixed powder is added into water for stirring.

10. A coalbed methane well, characterized in that: Cementing is performed using the cement slurry for coalbed methane wells as described in claim 8.

Images