High-density cement paste as well as preparation method and application thereof

Abstract

The invention provides high-density cement paste as well as a preparation method and application thereof. The high-density cement paste disclosed by the invention is prepared from the following components in parts by mass: 2 to 4 parts of dispersing agent PC-F45L, 1.2 to 1.5 parts of retarder PC-H40L, 5.5 to 6 parts of fluid loss agent PC-G80L, 0.5 to 1 part of defoaming agent, 38 to 42 parts of weighting agent, 98 to 102 parts of cement and 220 to 246 parts of water. The dispersing agent, the retarder and the fluid loss agent are specifically selected and compounded with other components, so that the obtained high-density cement paste cannot be thickened too early (the thickening time exceeds 400 minutes) in the grouting process, has better strength, sedimentation stability, rheological property and filtration loss property, and can well improve the well cementation quality.

Description

Technical Field

[0001] The present invention belongs to the field of drilling technology, and more specifically, relates to a high-density cement slurry and a preparation method and application thereof. Background Art

[0002] With the continuous development of oil and gas fields, oil and gas are buried deeper and deeper, and deep well (vertical wells of 4500-6000m) cementing operations have become more frequent. However, deep well cementing operations often face complex geological conditions such as high-pressure gas layers, and ordinary cement slurry is difficult to balance the pressure of the formation. Therefore, high-density cement slurry is often prepared by adding weighting agents to ordinary cement slurry to stabilize the high-pressure formation.

[0003] However, cement slurry containing weighting agents is prone to water loss during cementing due to its high density. To solve this problem, existing high-density cement slurries usually add fluid loss agents, but different types of fluid loss agents have a great influence on the rheology and thickening time of cement slurry, and the compatibility effect with other components of cement slurry is even more unpredictable. Therefore, in order to obtain a high-density cement slurry that will not thicken prematurely during the grouting process and has better rheological properties, it is necessary to screen a large number of components such as fluid loss agents and conduct targeted research on their compatibility. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and to provide a high-density cement slurry and a preparation method and application thereof. The present invention selects a fluid loss reducer specifically, combines a specific dispersant and a retarder, and compounding with other components, so that the obtained high-density cement slurry will not thicken prematurely during the grouting process (thickening time exceeds 400 minutes), and also has better sedimentation stability, rheology and filtration loss.

[0005] The first object of the present invention is to provide a high-density cement slurry.

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned high-density cement slurry.

[0007] The third object of the present invention is to provide application of the above-mentioned high-density cement slurry in well cementing.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The invention provides a high-density cement slurry, comprising the following components in parts by weight: 2 to 4 parts of a dispersant PC-F45L, 1.2 to 1.5 parts of a retarder PC-H40L, 5.5 to 6 parts of a fluid loss reducer PC-G80L, 0.5 to 1 part of a defoamer, 38 to 42 parts of a weighting agent, 98 to 102 parts of cement, and 220 to 246 parts of water.

[0010] The present invention specifically selects dispersants, retarders, and fluid loss agents, and compounding them with other ingredients, so that the high-density cement slurry obtained not only does not thicken prematurely during the grouting process (thickening time exceeds 400 minutes), but also has better strength, sedimentation stability, rheology and fluid loss, and can well improve the cementing quality. In addition, compared with high-density cement slurries using other dispersants, retarders, and fluid loss agents, the high-density cement slurry of the present invention has a longer thickening time and better rheology and fluid loss.

[0011] Preferably, the high-density cement slurry comprises the following components in parts by mass: 2 to 4 parts of dispersant PC-F45L, 1.2 to 1.5 parts of retarder PC-H40L, 5.5 to 6 parts of fluid loss reducer PC-G80L, 0.5 to 1 part of defoamer, 40 parts of weighting agent, 100 parts of cement, and 220 to 246 parts of water.

[0012] Preferably, the defoaming agent is one or more of PC-X60L and PC-X61L.

[0013] More preferably, the defoaming agent is PC-X60L.

[0014] Preferably, the weighting agent is a micro-manganese weighting agent.

[0015] Further preferably, the micro-manganese weighting agent is obtained by plasma atomization treatment of manganese tetraoxide with a mesh size of 300-425, or is Micromax.

[0016] More preferably, the conditions of the plasma atomization treatment are as follows: pressure of 0.8-1.2 MPa, power of 45-55 kW, atomization cooling distance of 110-150 mm, powder feeding amount of 1000-60000 g / min, argon as atomizing gas, gas flow rate of 320-360 m / s, 360° spray cooling crystallization, cooling crystallization time of 60-300 min.

[0017] Most preferably, the conditions of the plasma atomization treatment are as follows: pressure of 1 MPa, power of 50 kW, atomization cooling distance of 130 mm, powder feeding amount of 1000 g / min, argon as atomizing gas, gas flow rate of 340 m / s, 360° spray cooling crystallization, and cooling crystallization time of 90 min.

[0018] Preferably, the cement is Grade G cement.

[0019] Based on this, the present invention provides a method for preparing the above-mentioned high-density cement slurry, comprising adding dispersant PC-F45L, retarder PC-H40L, fluid loss reducer PC-G80L and defoamer into water, mixing evenly, and then adding weighting agent and cement, mixing evenly to obtain the high-density cement slurry.

[0020] Preferably, the mixing speed is 3800-4200 r / min.

[0021] The high-density cement slurry mentioned above will not thicken prematurely during the grouting process, and also has better strength, sedimentation stability, rheology and filtration properties, and can greatly improve the cementing quality. Therefore, the application of the high-density cement slurry mentioned above in cementing should be within the protection scope of the present invention.

[0022] The present invention has the following beneficial effects:

[0023] The present invention specifically selects dispersants, retarders and fluid loss reducers and compounding them with other components to obtain high-density cement slurry which not only does not thicken prematurely during the grouting process but also has better strength, sedimentation stability, rheology and filtration loss, and can well improve cementing quality. DETAILED DESCRIPTION

[0024] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0025] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0026] 1. Sources

[0027] Dispersants PC-F45L, PC-F41L, PC-F100s, retarders PC-H40L, PC-H41L, PC-H42L, fluid loss reducers PC-G80L, PC-G81L, PC-G80S, and defoamers PC-X60L, PC-X61L were all purchased from China Oilfield Services Limited.

[0028] 2. Material Preparation

[0029] (1) Preparation of manganese tetraoxide (300 mesh)

[0030] After adding water to the ferromanganese alloy waste until its solid content reaches 15wt%, magnetic separation is carried out in a magnetic separator at a magnetic field strength of 2T for 2h, and then sedimentation is carried out in a sedimentation tank for 24h, and the solid sediment layer is dried and calcined at a high temperature of 700℃ for 2h to obtain a calcined product. The calcined product and dispersant sodium hexametaphosphate are added to water (so that the concentrations of the calcined product and sodium hexametaphosphate in water are 40wt% and 1wt%, respectively), and ground by a sand mill at 120r / min to a coarse particle size of 80 mesh (monitored by a laser particle size analyzer), and then a water-based anti-adhesive agent J2301 is added (so that the concentration of the water-based anti-adhesive agent J2301 in water is 5wt%), and the fine particle size is continued to be 300 mesh.

[0031] (2) Preparation of manganese tetraoxide (400 mesh)

[0032] Same as trimanganese tetraoxide (300 mesh), the difference is that the particle size of coarse particles is 90 mesh and the particle size of fine particles is 400 mesh.

[0033] (3) Preparation of manganese tetraoxide (425 mesh)

[0034] Same as manganese tetraoxide (300 mesh), the difference is that the particle size of coarse particles is 100 mesh and the particle size of fine particles is 425 mesh.

[0035] Example 1 Preparation of high-density cement slurry

[0036] 1. Obtaining micro manganese weighting agent

[0037] Manganese tetraoxide (300 mesh) was fed into a plasma atomization device and subjected to plasma atomization treatment to obtain a micro-manganese weighting agent. The conditions for plasma atomization treatment were as follows: pressure of 1 MPa, power of 50 kW, atomization cooling distance of 130 mm, powder feeding amount of 1000 g / min, argon as atomization gas, gas flow rate of 340 m / s, 360° spray cooling crystallization, and cooling crystallization time of 90 min.

[0038] 2. Preparation of high-density cement slurry

[0039] Dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L are added to water, mixed at 4000r / min, and then micro-manganese weighting agent and G-grade cement are added, and mixed at 4000r / min to obtain high-density cement slurry. The mass ratio of the dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L, micro-manganese weighting agent, G-grade cement, and water is 2:1.5:6:0.5:40:100:246.

[0040] Example 2 Preparation of high-density cement slurry

[0041] 1. Obtaining micro manganese weighting agent

[0042] Manganese tetraoxide (300 mesh) was fed into a plasma atomization device and subjected to plasma atomization treatment to obtain a micro-manganese weighting agent. The conditions for the plasma atomization treatment were as follows: pressure of 0.8 MPa, power of 55 kW, atomization cooling distance of 110 mm, powder feeding amount of 30,000 g / min, argon as atomization gas, gas flow rate of 320 m / s, 360° spray cooling crystallization, and cooling crystallization time of 300 min.

[0043] 2. Preparation of high-density cement slurry

[0044] Dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L are added to water, mixed at 4200r / min, and then micro-manganese weighting agent and G-grade cement are added, and mixed at 4200r / min to obtain high-density cement slurry. The mass ratio of the dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L, micro-manganese weighting agent, G-grade cement, and water is 3:1.2:5.5:0.8:40:100:243.

[0045] Example 3 Preparation of high-density cement slurry

[0046] 1. Obtaining micro manganese weighting agent

[0047] Manganese tetraoxide (300 mesh) was fed into a plasma atomization device and subjected to plasma atomization treatment to obtain a micro-manganese weighting agent. The conditions for plasma atomization treatment were as follows: pressure of 1.2 MPa, power of 45 kW, atomization cooling distance of 150 mm, powder feeding amount of 60000 g / min, argon as atomization gas, gas flow rate of 360 m / s, 360° spray cooling crystallization, and cooling crystallization time of 60 min.

[0048] 2. Preparation of high-density cement slurry

[0049] Dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L are added to water, mixed at 3800r / min, and then micro-manganese weighting agent and G-grade cement are added, and mixed at 3800r / min to obtain high-density cement slurry. The mass ratio of the dispersant PC-F45L, retarder PC-H40L, fluid loss agent PC-G80L, defoamer PC-X60L, micro-manganese weighting agent, G-grade cement, and water is 4:1.5:6:1:40:100:220.

[0050] Example 4 Preparation of high-density cement slurry

[0051] 1. Obtaining micro manganese weighting agent

[0052] Same as Example 1.

[0053] 2. Preparation of high-density cement slurry

[0054] Same as Example 1, except that the defoamer PC-X60L is replaced by the defoamer PC-X61L.

[0055] Example 5 Preparation of high-density cement slurry

[0056] 1. Obtaining micro manganese weighting agent

[0057] Same as Example 1, except that the particle size of trimanganese tetraoxide is 400 mesh.

[0058] 2. Preparation of high-density cement slurry

[0059] Same as Example 1.

[0060] Example 6 Preparation of high-density cement slurry

[0061] 1. Obtaining micro manganese weighting agent

[0062] Same as Example 1, except that the particle size of trimanganese tetraoxide is 425 mesh.

[0063] 2. Preparation of high-density cement slurry

[0064] Same as Example 1.

[0065] Example 7 Preparation of high-density cement slurry

[0066] 1. Obtaining micro manganese weighting agent

[0067] Purchased from Elkem (Norway), model Micromax.

[0068] 2. Preparation of high-density cement slurry

[0069] Same as Example 1.

[0070] Comparative Example 1

[0071] 1. Obtaining micro manganese weighting agent

[0072] Same as Example 1.

[0073] 2. Preparation of high-density cement slurry

[0074] Same as Example 1, except that the retarder PC-H40L is replaced by the retarder PC-H41L.

[0075] Comparative Example 2

[0076] 1. Obtaining micro manganese weighting agent

[0077] Same as Example 1.

[0078] 2. Preparation of high-density cement slurry

[0079] Same as Example 1, except that the retarder PC-H40L is replaced by the retarder PC-H42L.

[0080] Comparative Example 3

[0081] 1. Obtaining micro manganese weighting agent

[0082] Same as Example 1.

[0083] 2. Preparation of high-density cement slurry

[0084] The same as Example 1, except that the fluid loss additive PC-G80L is replaced by the fluid loss additive PC-G81L.

[0085] Comparative Example 4

[0086] 1. Obtaining micro manganese weighting agent

[0087] Same as Example 1.

[0088] 2. Preparation of high-density cement slurry

[0089] The same as Example 1, except that the fluid loss agent PC-G80L is replaced by the fluid loss agent PC-G80S.

[0090] Comparative Example 5

[0091] 1. Obtaining micro manganese weighting agent

[0092] Same as Example 1.

[0093] 2. Preparation of high-density cement slurry

[0094] Same as Example 1, except that the fluid loss agent PC-G80L is replaced by the fluid loss agent PC-G84L.

[0095] Comparative Example 6

[0096] 1. Obtaining micro manganese weighting agent

[0097] Same as Example 1.

[0098] 2. Preparation of high-density cement slurry

[0099] Same as Example 1, except that the dispersant PC-F45L is replaced by the dispersant PC-F41L.

[0100] Comparative Example 7

[0101] 1. Obtaining micro manganese weighting agent

[0102] Same as Example 1.

[0103] 2. Preparation of high-density cement slurry

[0104] Same as Example 1, except that the dispersant PC-F45L is replaced by the dispersant PC-F100s.

[0105] Test Example 1

[0106] The high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 7 were placed in a 90° C. atmospheric pressure viscometer for curing for 20 min, and then their rheological properties were tested using a six-speed viscometer (speeds of 3, 6, 100, 200, and 300 rpm, respectively).

[0107] In addition, the high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 7 were placed in a 90°C atmospheric pressure thickener for curing for 20 minutes, and then the water loss was tested for 30 minutes by a high-temperature and high-pressure filter loss tester at 90°C and 6.9 MPa to characterize the filter loss property.

[0108] The results are shown in Table 1.

[0109] Table 1

[0110]

[0111]

[0112] visible:

[0113] (1) The absolute viscosity values ​​of the high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 3 at 3, 6, 100, 200, and 300 rpm are significantly smaller than those of Comparative Examples 3 to 6, and the absolute viscosity values ​​at 300 rpm are all less than 300 mPa·s, that is, the high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 3 have better fluidity and better rheological properties.

[0114] (2) The API water loss of the high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 2 is less than that in Comparative Examples 3 to 6, and is less than 50 mL, indicating that the high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 2 have good filtration performance, can effectively prevent the high-density cement slurry from penetrating into the formation, reduce damage to the formation, improve the stability of the well wall, and thus improve the cementing quality.

[0115] Test Example 2

[0116] The high-density cement slurries obtained in Examples 1 to 7 and Comparative Examples 1 to 2 and 5 were placed in a pressurized thickener, and their thickening time was tested at 115° C. and 60 MPa. The results are shown in Table 2.

[0117] Table 2

[0118] Thickening time (min) Example 1 493.7 Example 2 492.4 Example 3 490.5 Example 4 404.1 Example 5 435.6 Example 6 491.7 Example 7 492.2 Comparative Example 1 392.3 Comparative Example 2 388.5 Comparative Example 5 379.8

[0119] It can be seen that the thickening time of the high-density cement slurries obtained in Examples 1 to 7 is longer than that of Comparative Examples 1 to 2 and 5, and all reach more than 400 minutes, indicating that the high-density cement slurry of the present invention will not thicken prematurely during the grouting process, thereby ensuring the cementing quality.

[0120] Test Example 3

[0121] After measuring the density of the high-density cement slurry obtained in Examples 1 to 7, the high-density cement slurry was placed in a 200 mL measuring cylinder, the top of the measuring cylinder was sealed with plastic wrap and fixed with a rubber band, and the density was measured again after standing for 24 hours. The density difference before and after standing for 24 hours was calculated to characterize its sedimentation stability. The results are shown in Table 3.

[0122] Table 3

[0123] Temperature(℃) <![CDATA[Density before standing (g / cm 3 )]]> <![CDATA[Density after standing (g / cm 3 )]]> <![CDATA[Density difference (g / cm 3 )]]> Example 1 25 2.11 2.07 0.04 Example 2 25 2.10 2.08 0.02 Example 3 25 2.11 2.08 0.03 Example 4 25 2.11 2.09 0.02 Example 5 25 2.10 2.07 0.03 Example 6 25 2.10 2.09 0.01 Example 7 25 2.10 2.08 0.02

[0124] It can be seen that the density difference of the high-density cement slurries obtained in Examples 1 to 7 before and after standing is no more than 0.04 g / cm 3 , indicating that the high-density cement slurry of the present invention has relatively excellent sedimentation stability.

[0125] Test Example 4

[0126] The high-density cement slurry obtained in Examples 1 to 7 was placed in a test mold, and then the test mold was placed in a pressure curing kettle. After curing at 110°C and 21 MPa for 48 hours, the test mold was taken out and demoulded to obtain a sample, and then its strength was tested using a compressive strength testing machine (two parallel samples were set up). The results are shown in Table 4.

[0127] Table 4

[0128]

[0129] It can be seen that the strength of the high-density cement slurries obtained in Examples 1 to 7 is higher than 20 MPa, indicating that the high-density cement slurry of the present invention has high strength and will not break or fail when subjected to high pressure, and can be used in deep well cementing.

[0130] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A high-density cement slurry, characterized in that: The invention comprises the following components in parts by weight: 2 to 4 parts of dispersant PC-F45L, 1.2 to 1.5 parts of retarder PC-H40L, 5.5 to 6 parts of fluid loss reducer PC-G80L, 0.5 to 1 part of defoamer, 38 to 42 parts of weighting agent, 98 to 102 parts of cement and 220 to 246 parts of water.

2. The high-density cement slurry according to claim 1, characterized in that: The defoaming agent is one or more of PC-X60L and PC-X61L.

3. The high-density cement slurry according to claim 2, characterized in that: The defoamer is PC-X60L.

4. The high-density cement slurry according to claim 1, characterized in that: The weighting agent is a micro-manganese weighting agent.

5. The high-density cement slurry according to claim 4, characterized in that: The micro-manganese weighting agent is obtained by plasma atomization treatment of manganese tetraoxide with a size of 300-425 meshes.

6. The high-density cement slurry according to claim 5, characterized in that: The conditions of the plasma atomization treatment are as follows: pressure of 0.8-1.2 MPa, power of 45-55 kW, atomization cooling distance of 110-150 mm, powder feeding amount of 1000-60000 g / min, argon as atomizing gas, gas flow rate of 320-360 m / s, 360° spray cooling crystallization, cooling crystallization time of 60-300 min.

7. The high-density cement slurry according to claim 6, characterized in that: The conditions of the plasma atomization treatment are as follows: pressure of 1 MPa, power of 50 kW, atomization cooling distance of 130 mm, powder feeding amount of 1000 g / min, argon as atomizing gas, gas flow rate of 340 m / s, 360° spray cooling crystallization, and cooling crystallization time of 90 min.

8. The high-density cement slurry according to claim 1, characterized in that: The cement is Grade G cement.

9. The method for preparing high-density cement slurry according to any one of claims 1 to 8, characterized in that: Add dispersant PC-F45L, retarder PC-H40L, fluid loss reducer PC-G80L and defoamer into water, mix well, then add weighting agent and cement, mix well to obtain.

10. Use of the high-density cement slurry according to any one of claims 1 to 8 in well cementing.

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