Plugging composition for plugging dominant channel of oilfield water flow as well as preparation and application of plugging composition

Abstract

The invention discloses a plugging composition for plugging an oil field water flow dominant channel. The plugging composition contains ultrafine powder, a thickening regulator and a filtration regulator, wherein the ultrafine powder is prepared from 40.5 to 69.2 parts of hexagonal calcium silicate, 11.5 to 28.6 parts of calcite, 5.8 to 14.7 parts of clay mineral, 5.2 to 14.6 parts of quartz, 0 to 0.9 part of potassium feldspar, 0 to 2.6 parts of plagioclase, 0 to 0.6 part of dolomite, 0 to 2.1 parts of hornblende, 0 to 0.4 part of gypsum and 0 to 3.8 parts of anhydrite; the thickening regulator is sodium lignin sulfonate, hydroxymethyl cellulose and / or boric acid; the filtration property regulator is a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxy carboxylic acid, barium sulfate and / or 1788 type polyvinyl alcohol; the mass ratio of the thickening regulator to the ultrafine powder is (0.05-4): 100; the mass ratio of the filtration modifier to the ultrafine powder is (0.5-5): 100. The invention also discloses a preparation method and application thereof. The plugging composition provided by the invention can be matched with water flow dominant channels of reservoirs with different permeability.

Description

TECHNICAL FIELD

[0001] The present application relates to a plugging composition for plugging water flow dominant channels in oil fields and preparation and application thereof. BACKGROUND

[0002] Water injection development is a main way of oil reservoir development, but after water injection, dominant channels are formed in the reservoir, and injected water is inefficiently circulated in the reservoir, and the water content of produced liquid is high. The plugging and blocking technology for water flow dominant channels in oil reservoirs has always been an effective means to improve the development effect of water injection and realize stable production of oil reservoirs, and plays an extremely important role in different development stages of oil fields, and becomes the focus of the energy industry. The development of chemical plugging system is the core of this technology, which affects the development effect of water injection and chemical injection, and is of great significance to improve the recovery rate.

[0003] At present, the widely used chemical plugging materials for water flow dominant channels mainly include polymer gel, gel particle, flexible particle and polymer microsphere, etc. However, the above-mentioned plugging material systems have defects in plugging and migration performance, and it is difficult to meet the demand of efficient plugging of deep water flow dominant channels in oil reservoirs. Especially in high water cut old oil fields with highly developed water flow dominant channels, periodic and repeated plugging and blocking operations are needed, and the research on long-acting and efficient plugging materials suitable for different oil reservoir large channels has become a hot and difficult point for the research on greatly improving the recovery rate of high water cut old oil fields. SUMMARY

[0004] In order to improve the migration distance and plugging time of the plugging material at the same time, the present application provides a plugging composition. The plugging composition can be carried by water and injected into the formation, and can migrate in the deep part of the water flow dominant channel. After solidification, the plugging strength is high and the effective period is long, which can continuously expand the swept volume of water injection and chemical injection, and lay a foundation for improving the oil recovery rate.

[0005] As an aspect of the present application, a plugging composition for plugging water flow dominant channels in oil fields is provided, which contains superfine powder, thickening regulator and fluid loss regulator; the superfine powder includes 40.5-69.2 parts of hexagonal tobermorite, 11.5-28.6 parts of calcite, 5.8-14.7 parts of clay mineral, 5.2-14.6 parts of quartz, 0-0.9 parts of potassium feldspar, 0-2.6 parts of plagioclase, 0-0.6 parts of dolomite, 0-2.1 parts of hornblende, 0-0.4 parts of gypsum, 0-3.8 parts of anhydrite; the thickening regulator is sodium lignosulfonate, hydroxymethyl cellulose and / or boric acid; the fluid loss regulator is a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid, barium sulfate and / or polyvinyl alcohol type 1788; the mass ratio of the thickening regulator to the superfine powder is (0.05-4):100; the mass ratio of the fluid loss regulator to the superfine powder is (0.5-5):100.

[0006] In specific embodiments, the plugging composition further comprises water, and the mass ratio of (thickening regulator, fluid loss regulator and superfine powder) to water is 100:(40-120).

[0007] In specific embodiments, the fluid loss regulator is a terpolymer of 2-acrylamido-2-methylpropane sulfonic acid / acrylamide / hydroxycarboxylic acid, and the mass ratio of the fluid loss regulator to the superfine powder is (0.5-4): 100.

[0008] In specific embodiments, the superfine powder comprises 40.5-53.4 parts of tobermorite, 20.9-28.6 parts of calcite, 9.5-14.7 parts of clay mineral, 6.7-14.6 parts of quartz, 0.6-0.9 parts of potassium feldspar, 0.3-2.7 parts of plagioclase, 0.4-0.6 parts of dolomite, 0-1.1 parts of hornblende, 0.3-0.4 parts of gypsum and 0-3.8 parts of anhydrite; the thickening regulator is sodium lignosulfonate, and the fluid loss regulator is a terpolymer of 2-acrylamido-2-methylpropane sulfonic acid / acrylamide / hydroxycarboxylic acid. Further, the mass ratio of the thickening regulator to the superfine powder is (0.5-2): 100, the mass ratio of the fluid loss regulator to the superfine powder is (3-4): 100, and the mass ratio of (thickening regulator, fluid loss regulator and superfine powder) to water is 100:(100-120).

[0009] In specific embodiments, the particle size of the superfine powder ranges from 0.3 to 40 μm, D 10 = 0.52-0.89 μm, D 50 = 3.3-10.5 μm, D 90 = 14.8-19.6 μm, and the true density is 2-4 g / cm 3 .

[0010] As another aspect of the present application, a method for preparing the above-mentioned plugging composition is provided, which comprises: (1) mixing the superfine powder, the thickening regulator and the fluid loss regulator to obtain a mixture.

[0011] Further, it further comprises: (2) adding the mixture obtained in step (1) into water and stirring until the powder is uniformly dispersed.

[0012] As another aspect of the present application, the above-mentioned plugging composition is used in the development of oil and gas fields.

[0013] As another aspect of the present application, an oil and gas field development process is provided, which uses the above-mentioned plugging composition.

[0014] The sealing composition of the present invention has a simple preparation process, low particle size, can match the dominant water flow channels of reservoirs with different permeability, has good suspension, is easy to inject, and is convenient for on-site construction; the thickening time can be adjusted to meet the requirements of deep migration time; after curing, it has high strength, temperature and salt resistance, good sealing effect and long effective period.

[0015] The particle size range of the ultrafine powder used in this invention is 0.3-40 μm, D 10 =0.52–0.89 μm, D 50 =3.3–10.5 μm, D 90 =14.8–19.6 μm, actual density is 2–4 g / cm³ 3 With a water separation rate of <4.6% and good suspension properties, combined with its low particle size, this plugging system is easy to inject into the formation and facilitates on-site construction.

[0016] By optimizing the dosage of thickening modifier and the water / powder ratio, the thickening time of the plugging composition is controlled between 320 and 630 minutes. This ensures the migration time of the plugging system in the formation, meets the deep migration requirements, and reduces the risk of premature solidification of powder mud in the injection well during the construction process.

[0017] Physical simulation experiments show that the plugging composition has a good plugging effect on cores with different permeabilities, with a plugging rate of >83.3%, and up to 99.9%. Furthermore, in 2m sand-filled cores, it can be transported to the end of the core tube for deep placement. Meanwhile, considering that the main component of the plugging agent system is a rigid inorganic gel, which has excellent temperature and salt resistance, it is highly adaptable to reservoir temperature and formation water salinity. In addition, the plugging system has good erosion resistance; after plugging and injection of 50PV of water, the core permeability did not change, demonstrating its advantages of high strength and erosion resistance. Detailed Implementation

[0018] Experimental methods: To verify the performance of the embodiments, the suspension performance, thickening performance and plugging ability of the plugging composition were tested and evaluated. The preparation and performance evaluation methods of the plugging composition were in accordance with GB / T 10238-2015. The plugging performance evaluation used a sand-filled tube artificial core model with a length of 200cm and an inner diameter of 6.2cm.

[0019] In this application, unless otherwise stated, all parts are parts by weight.

[0020] The ultrafine powder used in this application has a particle size range of 0.3-40 μm and an actual density of 2-4 g / cm³. 3 D 10 =0.52-0.89μm, D 50 =3.3-10.5μm, D 90 =14.8-19.6μm.

[0021] 1. Preparation of the plugging composition

[0022] Example 1

[0023] (1) Mix 100g of ultrafine powder (main agent), 2g of sodium lignosulfonate (thickening regulator) and 3g of terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (filtration loss regulator) to obtain composite dry powder UP1;

[0024] (2) Add 105g of composite dry powder UP1 to 105g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 1.

[0025] The main components of the ultrafine powder (main agent) are:

[0026] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 53.4 20.9 9.5 6.7 0.4 3.8 0.6 2.7 1.1 0.9

[0027] The synthesis method of the terpolymer (filtration regulator) of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid is as follows:

[0028] A free radical polymerization method using aqueous solution was employed. 77g of distilled water was added to a beaker, along with 7.5g of 2-acrylamido-2-methylpropanesulfonic acid and 2.5g of hydroxycarboxylic acid, which were then dissolved by stirring. Sodium hydroxide was added to adjust the pH to 8, followed by the addition of 0.5g of acrylamide. The mixture was stirred until dissolved and then poured into a round-bottom flask. The stirring and heating devices were then activated. When the system temperature reached 60℃, 52.5mg of ammonium persulfate initiator was added, and the mixture was maintained at 60℃ for 120 minutes. The resulting viscous product was then evaporated to dryness, yielding a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (a filtration regulator).

[0029] Example 2

[0030] (1) Mix 100g of ultrafine powder (main agent), 3g of sodium lignosulfonate (thickening regulator) and 0.5g of terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (filtration regulator) to obtain composite dry powder UP2;

[0031] (2) Add 103.5g of composite dry powder UP2 to 41.4g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 2.

[0032] The main components of the ultrafine powder (main agent) are:

[0033] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0034] The synthesis method of the terpolymer (filtration regulator) of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid is as follows:

[0035] A free radical polymerization method using aqueous solution was employed. 77g of distilled water was added to a beaker, along with 7.5g of 2-acrylamido-2-methylpropanesulfonic acid and 2.5g of hydroxycarboxylic acid, which were then dissolved by stirring. Sodium hydroxide was added to adjust the pH to 8, followed by the addition of 0.5g of acrylamide. The mixture was stirred until dissolved and then poured into a round-bottom flask. The stirring and heating devices were then activated. When the system temperature reached 60℃, 52.5mg of ammonium persulfate initiator was added, and the mixture was maintained at 60℃ for 120 minutes. The resulting viscous product was then evaporated to dryness, yielding a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (a filtration regulator).

[0036] Example 3

[0037] (1) Mix 100g of ultrafine powder (main agent), 4g of hydroxymethyl cellulose (thickening regulator) and 1.5g of barium sulfate (filtration regulator) at room temperature to obtain composite dry powder UP3;

[0038] (2) Add 105.5g of composite dry powder UP3 to 42.2g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 3.

[0039] The main components of the ultrafine powder (main agent) are:

[0040] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0041] Example 4

[0042] (1) Mix 100g of ultrafine powder (main agent), 3.5g of boric acid (thickening regulator) and 1g of 1788 type polyvinyl alcohol (filtration regulator) at room temperature to obtain composite dry powder UP4;

[0043] (2) Add 104.5g of composite dry powder UP4 to 41.8g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 4.

[0044] The main components of the ultrafine powder (main agent) are:

[0045] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0046] Example 5

[0047] (1) Mix 100g of ultrafine powder (main agent), 0.05g of sodium lignosulfonate (thickening regulator) and 4g of barium sulfate (filtration loss regulator) to obtain composite dry powder UP5;

[0048] (2) Add 104.05g of composite dry powder UP5 to 125.4g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 5.

[0049] The main components of the ultrafine powder (main agent) are:

[0050] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0051] Example 6

[0052] (1) Mix 100g of ultrafine powder (main agent), 0.15g of boric acid (thickening regulator), and 3.8g of terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (filtration regulator) to obtain composite dry powder UP6;

[0053] (2) Add 103.95g of composite dry powder UP6 to 124.74g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 6.

[0054] The main components of the ultrafine powder (main agent) are:

[0055] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0056] The synthesis method of the terpolymer (filtration regulator) of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid is as follows:

[0057] A free radical polymerization method using aqueous solution was employed. 77g of distilled water was added to a beaker, along with 7.5g of 2-acrylamido-2-methylpropanesulfonic acid and 2.5g of hydroxycarboxylic acid, which were then dissolved by stirring. Sodium hydroxide was added to adjust the pH to 8, followed by the addition of 0.5g of acrylamide. The mixture was stirred until dissolved and then poured into a round-bottom flask. The stirring and heating devices were then activated. When the system temperature reached 60℃, 52.5mg of ammonium persulfate initiator was added, and the mixture was maintained at 60℃ for 120 minutes. The resulting viscous product was then evaporated to dryness, yielding a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (a filtration regulator).

[0058] Example 7

[0059] (1) Mix 100g of ultrafine powder (main agent), 0.6g of hydroxymethyl cellulose (thickening regulator) and 5g of 1788 type polyvinyl alcohol (filtration loss regulator) to obtain composite dry powder UP7;

[0060] (2) Add 105.6g of composite dry powder UP7 to 126.72g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 7.

[0061] The main components of the ultrafine powder (main agent) are:

[0062] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0063] Example 8

[0064] (1) Mix 100g of ultrafine powder (main agent), 0.5g of sodium lignosulfonate (thickening regulator), and 4g of terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (filtration regulator) to obtain composite dry powder UP8;

[0065] (2) Add 104.5g of composite dry powder UP8 to 125.4g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 8.

[0066] The main components of the ultrafine powder (main agent) are:

[0067] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 40.5 28.6 14.7 14.6 0.3 0 0.4 0.3 0 0.6

[0068] The synthesis method of the terpolymer (filtration regulator) of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid is as follows:

[0069] A free radical polymerization method using aqueous solution was employed. 77g of distilled water was added to a beaker, along with 7.5g of 2-acrylamido-2-methylpropanesulfonic acid and 2.5g of hydroxycarboxylic acid, which were then dissolved by stirring. Sodium hydroxide was added to adjust the pH to 8, followed by the addition of 0.5g of acrylamide. The mixture was stirred until dissolved and then poured into a round-bottom flask. The stirring and heating devices were then activated. When the system temperature reached 60℃, 52.5mg of ammonium persulfate initiator was added, and the mixture was maintained at 60℃ for 120 minutes. The resulting viscous product was then evaporated to dryness, yielding a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (a filtration regulator).

[0070] Example 9

[0071] (1) Mix 100g of ultrafine powder (main agent), 2.3g of hydroxymethyl cellulose (thickening regulator), and 2.5g of terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (filtration loss regulator) to obtain composite dry powder UP9;

[0072] (2) Add 104.8g of composite dry powder UP9 to 104.8g of water and stir until the powder is evenly dispersed to obtain the sealing composition Example 9.

[0073] The main components of the ultrafine powder (main agent) are:

[0074] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 40.5 28.6 14.7 14.6 0.3 0 0.4 0.3 0 0.6

[0075] The synthesis method of the terpolymer (filtration regulator) of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid is as follows:

[0076] A free radical polymerization method using aqueous solution was employed. 77g of distilled water was added to a beaker, along with 7.5g of 2-acrylamido-2-methylpropanesulfonic acid and 2.5g of hydroxycarboxylic acid, which were then dissolved by stirring. Sodium hydroxide was added to adjust the pH to 8, followed by the addition of 0.5g of acrylamide. The mixture was stirred until dissolved and then poured into a round-bottom flask. The stirring and heating devices were then activated. When the system temperature reached 60℃, 52.5mg of ammonium persulfate initiator was added, and the mixture was maintained at 60℃ for 120 minutes. The resulting viscous product was then evaporated to dryness, yielding a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid (a filtration regulator).

[0077] Comparative Example 1

[0078] Add 100g of ultrafine powder (main agent) to 100g of water and stir until the powder is evenly dispersed to obtain sealing composition comparative example 1.

[0079] The main components of the ultrafine powder (main agent) are:

[0080] Component tobermorite calcite clay mineral quartz gypsum anhydrite dolomite plagioclase amphibole potassium feldspar mass parts 69.2 11.5 5.8 5.2 0 3.6 0 2.6 2.1 0

[0081] 2. Thickening performance test of the sealing composition

[0082] The prepared sealing composition was loaded into the pre-assembled slurry cup of the high-temperature, high-pressure thickener. The slurry cup was then placed into the vessel of the high-temperature, high-pressure thickener. The motor was turned on, the vessel lid was tightened, the thermocouple was inserted, and oil was introduced. The test temperature was then set to 60℃ and the pressure to 20MPa. After the thickening oil filled the vessel, the screws were tightened, the program was started, and the corresponding switch was turned on to begin the thickening test. The time required for the consistency to reach 40 Bc was recorded, which is the thickening time of the system. The results are listed in Table 1.

[0083] Table 1 Thickening time of the plugging composition

[0084] Component tobermorite calcite clay mineral quartz gypsum 630 600 370 320 560 anhydrite dolomite plagioclase amphibole potassium feldspar mass parts Example 1 Example 2 Example 3 Example 4 Example 5 Thickening time / min Example 6 Example 7 Example 8 Example 9 Comparative Example 1 Thickening time / min 550 630 590 500 210

[0085] 2. Suspension performance test of the blocking composition

[0086] The prepared plugging composition was poured into a clean, dry 250 mL glass graduated cylinder. The cylinder was sealed with plastic film tape or an equivalent material to prevent moisture evaporation. The settling time was 120 min from the time the plugging composition was poured into the glass graduated cylinder. After 120 min of settling, the clear liquid precipitated from the top (colored or colorless liquid at the top) was removed using a pipette or syringe. The volume of the precipitated clear liquid was measured and recorded to an accuracy of ±0.1 mL, and this reading was taken as the number of milliliters of precipitated water. The percentage of precipitated water volume to the volume of the plugging composition, i.e., the water separation rate, was then calculated to evaluate the suspension performance of the system. The results are shown in Table 2. It can be seen that the water separation rate of the plugging composition is <4.6%, indicating good suspension. Combined with its low particle size characteristics, this plugging system is easy to inject into the formation.

[0087] Table 2. Water separation rate of the plugging composition

[0088]

[0089]

[0090] 3. Plugging performance testing of the plugging composition

[0091] Different mesh sizes of quartz sand were prepared according to permeability requirements. These were then manually filled into 200cm long, 6.2cm inner diameter oil pipes and compacted to obtain sand-filled core tubes with different permeabilities. A high-pressure shut-off valve, pressure sensor, and heating insulation tape were connected, and all components were tightened. The performance of the profile control agent was then evaluated.

[0092] During the test, the sand-filled pipe was first saturated with water, and then clean water was injected at a rate of 10 L / h until the pressure stabilized. The pressure value was recorded, and the original permeability K1 was calculated. Then, the sealing composition (2 PV) was injected at a rate of 33.3 L / h, and the mixture was allowed to solidify at 60℃ for 24 hours. Subsequently, water drive was performed at a rate of 10 L / h until the pressure at the measuring point reached equilibrium. The pressure value was recorded, and the post-plugging permeability K2 was calculated. The plugging rate was calculated using (K1-K2) / K1, and the results are shown in Table 3. It can be seen that the sealing composition produced a good plugging effect on cores with different permeabilities, with a plugging rate >83.3%, reaching a maximum of 99.9%. Simultaneously, the plugging system exhibited good erosion resistance; after plugging, the core permeability remained unchanged after injecting 50 PV of water, demonstrating advantages of high strength and erosion resistance. Finally, the core tube was dissected, and the transport distance of the ultrafine powder within the core tube was measured. The results are shown in Table 4. It can be seen that the sealing composition can be transported as far as the end of the core tube in a 2m sand-filled rock core, achieving deep placement.

[0093] Table 3. Plugging efficiency of the plugging composition for different sand-filled cores.

[0094]

[0095] Table 4. Migration distance of the sealing composition in different sand-filled cores.

[0096]

[0097]

[0098] Based on the above embodiments and comparative examples, it can be seen that a composition consisting of 40.5-69.2 parts hexagonal calcium silicate, 11.5-28.6 parts calcite, 5.8-14.7 parts clay minerals, 5.2-14.6 parts quartz, 0-0.9 parts potassium feldspar, 0-2.6 parts plagioclase, 0-0.6 parts dolomite, 0-2.1 parts amphibole, 0-0.4 parts gypsum, and 0-3.8 parts anhydrite is used as the ultrafine powder (main agent), with sodium lignosulfonate, hydroxymethyl cellulose, and / or boric acid as thickening regulators, and 2-acrylamido-2-methylpropane... The terpolymer of sulfonic acid / acrylamide / hydroxycarboxylic acid, barium sulfate and / or polyvinyl alcohol of type 1788 were used as filtration modifiers. The mass ratio of thickening modifier to ultrafine powder was (0.05-4):100, and the mass ratio of filtration modifier to ultrafine powder main agent was (0.5-5):100. The plugging composition obtained by the composite dry powder composed of thickening modifier, filtration modifier and ultrafine powder (main agent) with a mass ratio of water of 100:(40-120) was significantly better than the comparative example in terms of thickening time, suspension performance, plugging rate and transport distance.

[0099] Furthermore, a comparison within the examples reveals that Examples 2, 6, 8, and 9, using a terpolymer of 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid as a filtration modifier, with a mass ratio of filtration modifier to ultrafine powder main agent of (0.5-4):100, and a mass ratio of composite dry powder composed of thickening modifier, filtration modifier, and ultrafine powder (main agent) to water of 100:(40-120), resulted in a blocking composition that was significantly superior to other examples in terms of suspension performance and transport distance.

[0100] Furthermore, in Examples 1 and 8, an ultrafine powder (main agent) was composed of 40.5-53.4 parts hexagonal calcium silicate, 20.9-28.6 parts calcite, 9.5-14.7 parts clay minerals, 6.7-14.6 parts quartz, 0.6-0.9 parts potassium feldspar, 0.3-2.7 parts plagioclase, 0.4-0.6 parts dolomite, 0-1.1 parts amphibole, 0.3-0.4 parts gypsum, and 0-3.8 parts anhydrite, with sodium lignosulfonate as a thickening regulator, and 2-acrylamido-2-methylpropanesulfonic acid / acrylamide. The terpolymer of hydroxycarboxylic acid was used as a filtration modifier. The mass ratio of thickening modifier to ultrafine powder main agent was 0.5:100-2:100, and the mass ratio of filtration modifier to ultrafine powder main agent was 3:100-4:100. The mass ratio of composite dry powder composed of thickening modifier, filtration modifier and ultrafine powder (main agent) to water was 100:100-100:120. The resulting plugging composition was significantly better than the comparative example in terms of thickening time, suspension performance, plugging rate and transport distance. The optimal plugging composition was prepared.

Claims

1. A plugging composition for plugging flow channels of preference of oilfield water, characterized in that, The plugging composition contains superfine powder, thickening regulator and fluid loss regulator; wherein the superfine powder comprises 40.5-69.2 parts of tobermorite, 11.5-28.6 parts of calcite, 5.8-14.7 parts of clay mineral, 5.2-14.6 parts of quartz, 0-0.9 parts of potassium feldspar, 0-2.6 parts of plagioclase, 0-0.6 parts of dolomite, 0-2.1 parts of hornblende, 0-0.4 parts of gypsum and 0-3.8 parts of anhydrite; the thickening regulator is sodium lignosulfonate, hydroxymethyl cellulose and / or boric acid; the fluid loss regulator is 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid terpolymer, barium sulfate and / or polyvinyl alcohol type 1788; the mass ratio of the thickening regulator to the superfine powder is (0.05-4):100; and the mass ratio of the fluid loss regulator to the superfine powder is (0.5-5):

100.

2. The plugging composition of claim 1, wherein, The plugging composition further contains water, and the mass ratio of (thickening regulator, fluid loss regulator and superfine powder) to water is 100:(40-120).

3. The plugging composition of claim 1, wherein The fluid loss regulator is 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid terpolymer, and the mass ratio of the fluid loss regulator to the superfine powder is (0.5-4):

100.

4. The plugging composition of claim 1, wherein The superfine powder comprises 40.5-53.4 parts of tobermorite, 20.9-28.6 parts of calcite, 9.5-14.7 parts of clay mineral, 6.7-14.6 parts of quartz, 0.6-0.9 parts of potassium feldspar, 0.3-2.7 parts of plagioclase, 0.4-0.6 parts of dolomite, 0-1.1 parts of hornblende, 0.3-0.4 parts of gypsum and 0-3.8 parts of anhydrite; the thickening regulator is sodium lignosulfonate, and the fluid loss regulator is 2-acrylamido-2-methylpropanesulfonic acid / acrylamide / hydroxycarboxylic acid terpolymer.

5. The occlusive composition of claim 4, wherein, The mass ratio of the thickening regulator to the superfine powder is (0.5-2):100, the mass ratio of the fluid loss regulator to the superfine powder is (3-4):100, and the mass ratio of (thickening regulator, fluid loss regulator and superfine powder) to water is 100:(100-120).

6. The occlusive composition of any one of claims 1-5, wherein, The particle size of the superfine powder ranges from 0.3 to 40 μm, D 10 = 0.52 - 0.89 μm, D 50 = 3.3 - 10.5 μm, D 90 = 14.8 - 19.6 μm, and the true density is 2 - 4 g / cm 3 .

7. A process for the preparation of a plugging composition according to any one of claims 1 to 6, characterized in that, It comprises: (1) mixing the superfine powder, the thickening regulator and the fluid loss regulator to obtain a mixture.

8. The method of claim 7, wherein, It further comprises: (2) adding the mixture obtained in step (1) into water and stirring until the powder is uniformly dispersed.

9. Use of the plugging composition according to any one of claims 1-6 in oil and gas field development.

10. An oil and gas field development process using the plugging composition according to any one of claims 1-6.

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