A weighting material for drilling fluid and its preparation method

Abstract

The present invention belongs to the technical field of oilfield chemicals, and specifically discloses a weighting material for drilling fluid and a preparation method thereof. The present invention first grades barite powder of a specific particle size to obtain a composite barite powder; then mixes it with a 2-acrylamide-2-methylpropanesulfonic acid solution, and dries to obtain a surface-modified barite powder; then the surface-modified barite powder is mixed with a composite modifier prepared by acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10 and water, and dried to obtain a weighting material for drilling fluid. The weighting material for drilling fluid prepared by the present invention has a higher density and good water dispersibility and stability. It is applied to the drilling fluid to embody good rheological properties, so that the drilling fluid has a lower viscosity.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemicals, in particular to a weighting material for drilling fluid and a preparation method thereof. Background Art

[0002] As oil and gas exploration and development continue to deepen, the exploration and development field is gradually shifting to deep and ultra-deep layers, complex formations, deep-sea polar regions and unconventional oil and gas reservoirs, which puts higher requirements on drilling engineering. Petroleum additives, which can improve product performance, increase production efficiency and reduce production costs in the process of oil processing and petrochemical production, also need to meet higher requirements.

[0003] As exploration and development develops in depth, the number of deep and ultra-deep wells drilled increases, and the research on high-density drilling fluid weighting agents will inevitably receive more and more attention. The most commonly used weighting agent in drilling fluid is barite; others include calcium carbonate with low density, iron ore powder, manganese tetroxide and galena powder with high density. The addition of weighting agents increases the solid content of drilling fluid, resulting in poor rheological properties, filtration wall-building properties and lubricity of drilling fluid. The content of solid phase weighting particles in high-density drilling fluid is high, and its solid phase particles participate in the formation of the drilling fluid gel structure. In high-density drilling fluid, especially in ultra-high-density drilling fluid, the probability of contact and collision of weighting particles increases, the friction resistance between particles increases, and a strong flow resistance is formed, resulting in a significant increase in the viscosity of the system and poor rheological properties. Moreover, some current methods for improving barite powder will also lead to a decrease in the density of barite powder, weakening the weighting effect of barite powder.

[0004] Therefore, how to provide a weighting material for drilling fluid and a preparation method thereof, ensure the density of barite powder, and improve its rheological properties and filtration and wall-building properties during application is a difficult problem to be solved urgently in this field. Summary of the invention

[0005] In view of this, the present invention provides a weighting material for drilling fluid and a preparation method thereof, so as to solve the problems that the existing modified weighting material has low density and easily causes poor rheological properties of drilling fluid during the application process.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing a weighting material for drilling fluid comprises the following steps:

[0008] 1) mixing the composite barite powder with a 2-acrylamide-2-methylpropanesulfonic acid solution, and drying to obtain a surface-modified barite powder;

[0009] 2) mixing the surface-modified barite powder with the composite modifier and drying to obtain a weighting material for drilling fluid;

[0010] Among them, the composite modifier includes acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10, and water.

[0011] Preferably, the composite barite powder includes small-sized barite powder, medium-sized barite powder, and large-sized barite powder;

[0012] Among them, the particle size of the small-sized barite powder < 0.048 mm, the particle size of the medium-sized barite powder is 0.048 - 0.075 mm, and the particle size of the large-sized barite powder > 0.075 mm.

[0013] Preferably, the mass ratio of the small-sized barite powder, medium-sized barite powder, and large-sized barite powder in the composite barite powder is 4 - 6:1 - 3:1 - 3.

[0014] Preferably, the mass-volume ratio of the composite barite powder and the 2-acrylamido-2-methylpropanesulfonic acid solution is 100 g:30 - 60 mL.

[0015] Preferably, the mass concentration of the 2-acrylamido-2-methylpropanesulfonic acid solution is 1.5 - 5%.

[0016] Preferably, the mixing in step 1) includes stirring and dispersing, and the time for stirring and dispersing is 10 - 20 min.

[0017] Preferably, the mass ratio of acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10, and water in the composite modifier is 0.15 - 0.3:0.2 - 0.4:0.2 - 0.4:100.

[0018] Preferably, the mass ratio of the composite modifier to the surface-modified barite powder is 20 - 30:100.

[0019] Preferably, the mixing in step 2) includes stirring and mixing, the time for stirring and mixing is 30 - 60 min, and the stirring and mixing rate is 400 - 1200 rpm.

[0020] Another object of the present invention is to provide a weighting material for drilling fluid prepared by the above preparation method.

[0021] Through the above technical solutions, compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The present invention specifies the specific particle size of barite powder and details the specific gravity of barite powder in each particle size range. By performing particle size grading on barite powder, the rheological properties during the application of barite powder are significantly improved, and as the density of the drilling fluid increases, the improvement effect increases; at the same time, the adopted particle size is conducive to surface modification, ensuring that the weighting density will not be too low while improving the comprehensive performance of barite powder;

[0023] 2. First, the barite powder is coated and surface-modified with 2-acrylamido-2-methylpropanesulfonic acid, and then the modified barite powder reacts with the composite modifier to bind components such as acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10 to the barite powder, thereby improving the water dispersibility, stability and rheological properties of the barite powder;

[0024] 3. The method disclosed by the present invention is simple and easy to implement, with obvious effect improvement, and is suitable for popularization and application. Detailed implementation mode

[0025] The present invention provides a preparation method of a weighting material for drilling fluid, comprising the following steps:

[0026] 1) Mix the composite barite powder with 2-acrylamido-2-methylpropanesulfonic acid solution and dry to obtain surface-modified barite powder;

[0027] 2) Mix the surface-modified barite powder with the composite modifier and dry to obtain a weighting material for drilling fluid.

[0028] In the present invention, the composite modifier includes acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10, and water.

[0029] In the present invention, the composite barite powder includes small-particle-size barite powder, medium-particle-size barite powder and large-particle-size barite powder; the particle size of the small-particle-size barite powder is <0.048 mm, the particle size of the medium-particle-size barite powder is 0.048 - 0.075 mm, and the particle size of the large-particle-size barite powder is >0.075 mm.

[0030] In the present invention, the mass ratio of the small-particle-size barite powder, medium-particle-size barite powder and large-particle-size barite powder in the composite barite powder is 4 - 6:1 - 3:1 - 3; preferably 4.2 - 5.8:1.2 - 2.8:1.2 - 2.8; more preferably 4.5 - 5.5:1.5 - 2.5:1.5 - 2.5; further preferably 4.8 - 5.2:1.8 - 2.2:1.8 - 2.2; still more preferably 5:2:2.

[0031] In the present invention, the mass-volume ratio of the composite barite powder and 2-acrylamido-2-methylpropanesulfonic acid solution is 100 g:30 - 60 mL; preferably 100 g:35 - 55 mL; further preferably 100 g:40 - 50 mL; still more preferably 100 g:45 mL.

[0032] In the present invention, the mass concentration of the 2-acrylamido-2-methylpropanesulfonic acid solution is 1.5 to 5%, specifically it can be 1.8%, 2%, 2.2%, 2.5%, 2.6%, 3%, 3.2%, 3.6%, 4%, 4.4%, 4.8%.

[0033] In the present invention, the mixing in step 1) includes stirring and dispersing, and the time for stirring and dispersing is 10 to 20 min, specifically it can be 12 min, 14 min, 15 min, 16 min, 18 min.

[0034] In the present invention, the stirring and dispersing in step 1) is preferably carried out by using a high-speed mixer, and the stirring rate is preferably 6000 to 11000 rpm, specifically it can be 7000 rpm, 8000 rpm, 9000 rpm, 10000 rpm.

[0035] In the present invention, the mass ratio of acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10 and water in the composite modifier is 0.15 to 0.3:0.2 to 0.4:0.2 to 0.4:100; preferably 0.18 to 0.28:0.23 to 0.36:0.23 to 0.36:100; further preferably 0.2 to 0.25:0.25 to 0.35:0.25 to 0.35:100; still further preferably 0.21 to 0.23:0.28 to 0.32:0.28 to 0.32:100; more preferably 0.22:0.3:0.3:100.

[0036] In the present invention, the polyethylene glycol includes one or more of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, polyethylene glycol 800, and polyethylene glycol 1000.

[0037] In the present invention, the preparation method of the composite modifier is: acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10 and water with defined ratios are fully mixed to obtain the composite modifier.

[0038] In the present invention, the mass ratio of the composite modifier to the surface-modified barite powder is 20 to 30:100; preferably 22 to 28:100; further preferably 24 to 26:100; still further preferably 25:100.

[0039] In the present invention, the mixing in step 2) includes stirring and mixing, and the time for stirring and mixing is 30 to 60 min, specifically it can be 22 min, 24 min, 25 min, 26 min, 28 min, 30 min, 32 min, 35 min, 38 min; the rate of stirring and mixing is 400 to 1200 rpm, specifically it can be 500 rpm, 600 rpm, 700 rpm, 800 rpm, 900 rpm, 1000 rpm, 1100 rpm.

[0040] The present invention also provides a weighting material for drilling fluid prepared by the said preparation method.

[0041] Next, the technical solutions in the embodiments of the present invention will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0042] Example 1

[0043] Prepare composite barite powder: Take 25 parts of barite powder with a particle size less than 0.048 mm, 10 parts of barite powder with a particle size of 0.048 - 0.075 mm, and 15 parts of barite powder with a particle size of 0.075 mm - 0.106 mm, and stir and mix them thoroughly.

[0044] Prepare composite modifier: Mix acrylamide, polyethylene glycol 600, octylphenol polyoxyethylene ether - 10 and water according to a mass ratio of 0.2:0.25:0.3:100 to obtain the composite modifier.

[0045] Take 1000 g of composite barite powder and 300 mL of 2 - acrylamido - 2 - methylpropanesulfonic acid solution (mass concentration of 2%) and stir and disperse them at 6000 rpm for 15 min, then dry to obtain surface - modified barite powder; Weigh the composite modifier and the surface - modified barite powder according to a mass ratio of 260:1000, mix and stir them at a rate of 500 rpm for 35 min, and then dry and pulverize to obtain the weighting material for drilling fluid.

[0046] Example 2

[0047] Prepare composite barite powder: Take 20 parts of barite powder with a particle size less than 0.048 mm, 5 parts of barite powder with a particle size of 0.048 - 0.075 mm, and 8 parts of barite powder with a particle size of 0.075 mm - 0.106 mm, and stir and mix them thoroughly.

[0048] Prepare the composite modifier: Mix acrylamide, polyethylene glycol 600, octylphenol polyoxyethylene ether-10, and water in a mass ratio of 0.15:0.3:0.3:100 to obtain the composite modifier.

[0049] Take 1000 g of composite barite powder and 350 mL of 2-acrylamido-2-methylpropanesulfonic acid solution (mass concentration of 1.5%) and stir and disperse them at 8000 rpm for 10 min, then dry to obtain surface-modified barite powder; Weigh the composite modifier and the surface-modified barite powder in a mass ratio of 240:1000, mix and stir them at a rate of 400 rpm for 30 min, and then dry and pulverize to obtain the weighting material for drilling fluid.

[0050] Example 3

[0051] Prepare the composite barite powder: Take 26 parts of barite powder with a particle size less than 0.048 mm, 10 parts of barite powder with a particle size of 0.048 - 0.075 mm, and 9 parts of barite powder with a particle size of 0.075 mm - 0.106 mm, and stir and mix them well.

[0052] Prepare the composite modifier: Mix acrylamide, polyethylene glycol 400, octylphenol polyoxyethylene ether-10, and water in a mass ratio of 0.15:0.2:0.25:100 to obtain the composite modifier.

[0053] Take 1000 g of composite barite powder and 600 mL of 2-acrylamido-2-methylpropanesulfonic acid solution (mass concentration of 1.5%) and stir and disperse them at 6000 rpm for 15 min, then dry to obtain surface-modified barite powder; Weigh the composite modifier and the surface-modified barite powder in a mass ratio of 200:1000, mix and stir them at a rate of 600 rpm for 40 min, and then dry and pulverize to obtain the weighting material for drilling fluid.

[0054] Example 4

[0055] Prepare the composite barite powder: Take 30 parts of barite powder with a particle size less than 0.048 mm, 15 parts of barite powder with a particle size of 0.048 - 0.075 mm, and 10 parts of barite powder with a particle size of 0.075 mm - 0.106 mm, and stir and mix them well.

[0056] Prepare the composite modifier: Mix acrylamide, polyethylene glycol 800, octylphenol polyoxyethylene ether-10, and water in a mass ratio of 0.3:0.4:0.35:100 to obtain the composite modifier.

[0057] Take 1000 g of composite barite powder and 400 mL of 2 - acrylamido - 2 - methylpropanesulfonic acid solution (mass concentration is 5%) and stir - disperse them at 10000 rpm for 15 min, then dry to obtain surface - modified barite powder; Weigh the composite modifier and the surface - modified barite powder according to the mass ratio of 280:1000, mix and stir at a rate of 400 rpm for 50 min, and then dry and pulverize to obtain the weighting material for drilling fluid.

[0058] After testing (GB / T5005 - 2010 - Le Chatelier flask method), the densities of the weighting materials for drilling fluid obtained in Examples 1 - 4 are all greater than 4.2 g / cm 3 , meeting the primary index.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is only that only barite powder with a particle size less than 0.048 mm is used for modification.

[0061] Comparative Example 2

[0062] The difference between this comparative example and Example 1 is only that no surface modification with 2 - acrylamido - 2 - methylpropanesulfonic acid solution is carried out.

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is only that acrylamide is not added to the composite modifier.

[0065] Experimental Example 1

[0066] Add the weighting materials for drilling fluid obtained in Examples 1 - 4 and Comparative Examples 1 - 3 to the basic drilling fluid, adjust the density of the drilling fluid to 2.4 g / cm 3 , stir at high speed for 20 min, and measure its apparent viscosity, API filtration loss, and high - temperature and high - pressure filtration loss according to GB / T 16783.1 - 2014. The test results are shown in Table 1:

[0067] Table 1 Test results of viscosity and filtration loss

[0068]

[0069] It can be seen from the data in Table 1 that the apparent viscosity of the weighting material for drilling fluid prepared by the present invention is less than that of Comparative Examples 1 - 3. Using the weighting material for drilling fluid of the present invention can reduce the viscosity of the drilling fluid; and through Comparative Example 1, it can be seen that the barite powder gradation disclosed by the present invention is beneficial to reducing the apparent viscosity of the drilling fluid. The weighting material disclosed by the present invention also has a lower filtration loss, and can form a thinner filter cake on the rock wall during use, showing better filtration performance.

[0070] Experimental Example 2

[0071] The weighting materials for drilling fluids obtained in Example 1 and Comparative Examples 1 to 3 were added to the base drilling fluid. At the same time, a control example (the untreated composite barite powder in Example 1) was set, and the density of the drilling fluid was adjusted to 2.4 g / cm 3 , and it was left standing for 2 h. Then, the density was measured again using a densitometer.

[0072] Table 2 Density test results

[0073]

[0074] It can be seen from Table 2 that the density change of the present invention before and after standing is small and the stability is good; in Comparative Example 1, the modification method is the same as that of the present invention, but the specific grading method is different, and the specific surface area is larger, which may cause some raw materials with small particle sizes to not be effectively modified, and thus the stability is slightly worse; the stabilities of Comparative Example 2, Comparative Example 3 and the control example are far inferior to that of the present invention.

[0075] In this specification, the various embodiments are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same and similar parts among the various embodiments, reference can be made to each other.

[0076] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A preparation method of a weighting material for drilling fluid, characterized in that, it comprises the following steps: 1) Mix the composite barite powder with 2-acrylamido-2-methylpropanesulfonic acid solution, and dry to obtain surface-modified barite powder; 2) Mix the surface-modified barite powder with a composite modifier, and dry to obtain a weighting material for drilling fluid; wherein, the composite modifier comprises acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10, and water; the composite barite powder comprises small-particle-size barite powder, medium-particle-size barite powder, and large-particle-size barite powder; wherein, the particle size of the small-particle-size barite powder < 0.048 mm, the particle size of the medium-particle-size barite powder is 0.048 - 0.075 mm, and the particle size of the large-particle-size barite powder > 0.075 mm; the mass ratio of the small-particle-size barite powder, medium-particle-size barite powder, and large-particle-size barite powder in the composite barite powder is 4 - 6:1 - 3:1 - 3; the mass-volume ratio of the composite barite powder and 2-acrylamido-2-methylpropanesulfonic acid solution is 100 g:30 - 60 mL; the mass concentration of the 2-acrylamido-2-methylpropanesulfonic acid solution is 1.5 - 5%; the mass ratio of acrylamide, polyethylene glycol, octylphenol polyoxyethylene ether-10, and water in the composite modifier is 0.15 - 0.3:0.2 - 0.4:0.2 - 0.4:100; the mass ratio of the composite modifier to the surface-modified barite powder is 20 - 30:

100.

2. The preparation method of a weighting material for drilling fluid according to claim 1, characterized in that, the mixing in step 1) includes stirring and dispersing, and the time of stirring and dispersing is 10 - 20 min.

3. The preparation method of a weighting material for drilling fluid according to claim 1, characterized in that, the mixing in step 2) includes stirring and mixing, the time of stirring and mixing is 30 - 60 min, and the stirring and mixing rate is 400 - 1200 rpm.

4. A weighting material for drilling fluid prepared by the preparation method according to any one of claims 1 - 3.

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