Bottom water shielding system and bottom water shielding method

Abstract

The invention provides a bottom water shielding system and a bottom water shielding method. The bottom water shielding system comprises a dilution-resistant gel system, a mineral powder gel system and a high-temperature gel system. According to the bottom water shielding method provided by the invention, the bottom water shielding system is adopted, bottom water shielding is carried out according to a slug combination mode, and a good treatment effect is achieved on the high-water-content well of the karst cave type reservoir body.

Description

Technical Field

[0001] The invention belongs to the technical field of water plugging and recovery in cavernous oil reservoirs, and in particular relates to a bottom water shielding system and a bottom water shielding method. Background Art

[0002] The karst-type reservoirs are usually developed near faults. The area is filled with oil and gas, with a cumulative production of more than 100,000 tons. Due to the single bottom water rising channel and the rapid increase in water content, the shielding pressure difference of the water body reaches 8MPa, which is prone to violent flooding. The bottom water shielding blocks the remaining oil laterally, resulting in the enrichment of the remaining oil around the well. The water plugging segment design of temperature-resistant gel + temperature-resistant gel + resin developed in the early stage has the problems of insufficient plugging strength and short effective period of water plugging after well opening. It often only has a short period of oil increase effect, and then the water content rises rapidly and the remaining oil is blocked. The deep water plugging methods reported so far also have the following problems:

[0003] (1) There is no perfect reagent system. In view of the fact that the bottom water in cave reservoirs has strong energy, a perfect reagent system has not been formed, and the composition and performance of the reagents have not been clearly explained;

[0004] (2) The slugs are complex and the construction cost is high. The slugs used in the current water plugging methods for cavernous reservoirs are usually relatively complex, and some even have 6 to 7 slugs. The construction cost and the performance of the injection agent have not been considered in depth.

[0005] (3) The study mainly focused on the arrangement and adaptability of plugging agents, without emphasizing the amount, combination, properties and other parameters of the plugs. The water plugging of cave-type reservoirs and how to shield strong bottom water were not elaborated.

[0006] In summary, there is an urgent need to develop a design method for high-strength shielding bottom water plugs for cave-type reservoirs. The high-strength shielding effect can suppress the rapid breakthrough of bottom water, improve the current situation of high water content in oil wells, and provide support for improving the recovery rate of cave-type reservoirs. Summary of the invention

[0007] One of the present inventions provides a bottom water shielding system, which includes a dilution-resistant jelly system, a mineral powder jelly system and a high-temperature gel system.

[0008] In the present invention, bottom water refers to the water that fills the bottom of oil and gas and supports the oil and gas during oil field production.

[0009] According to a specific embodiment of the present invention, the dilution-resistant gel system comprises polyacrylamide, 2-acrylamide-2-methylpropane sulfonic acid, N-hetero long-chain alkyl acrylamide monomer, deoxidizer, phenol crosslinking agent and aldehyde crosslinking agent; and / or

[0010] The mineral powder jelly system comprises polyvinyl alcohol, polyacrylic acid, phenolic crosslinking agent and bentonite; and / or

[0011] The high temperature gel system comprises water glass and carbon amide.

[0012] According to a specific embodiment of the present invention, the mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.8 to 1 wt% polyacrylamide, 0.6 to 0.8 wt% 2-acrylamide-2-methylpropane sulfonic acid, 0.6 to 0.8 wt% N-hetero long-chain alkyl acrylamide monomer, 0.2 to 0.4 wt% deoxidizer, 0.7 to 0.9 wt% phenol crosslinker, 0.7 to 0.9 wt% aldehyde crosslinker and the balance water.

[0013] According to a specific embodiment of the present invention, the mass of the mineral powder jelly system is calculated as 100%, and the mineral powder jelly system includes 2 to 2.5 wt% polyvinyl alcohol, 1 to 1.5 wt% polyacrylic acid, 9 to 11 wt% phenolic crosslinker, 52 to 54 wt% bentonite and the balance water.

[0014] According to a specific embodiment of the present invention, the mass of the water glass is calculated as 100%, and the amount of the carbonic acid amide is 2 to 3 wt%.

[0015] According to a specific embodiment of the present invention, the molecular weight of the polyacrylamide is 2×10 5 ; and / or

[0016] The molecular weight of the N-hetero long-chain alkyl acrylamide monomer is 1×10 4 ; and / or

[0017] The molecular weight of the polyvinyl alcohol is 120,000 to 150,000; and / or

[0018] The molecular weight of the polyacrylic acid is 5000; and / or

[0019] The deoxidizer is thiourea; and / or

[0020] The phenolic cross-linking agent is hydroquinone; and / or

[0021] The aldehyde cross-linking agent is hexamethylenetetramine; and / or

[0022] The phenolic cross-linking agent is a product obtained by condensation of alkylphenol and formaldehyde;

[0023] Preferably, the N-hetero long-chain alkyl acrylamide monomer is purchased from Dongying Dayong Petroleum Additives Co., Ltd.

[0024] The second aspect of the present invention provides a bottom water shielding method, which uses the bottom water shielding system described in the first aspect of the present invention to perform bottom water shielding in a slug combination manner;

[0025] 1) The dilution-resistant gel system is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way;

[0026] 2) The mineral powder jelly system is injected into the ground as the main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range;

[0027] 3) injecting the dilution-resistant gel system into the ground as a post-segment plug to enhance the shielding effect of the main segment plug and seal the cracks around the well;

[0028] 4) Injecting the high temperature gel system as a sealing slug to prevent the front slug, the main slug and the rear slug from spitting back, thereby reducing the damage to the tubular string in the well.

[0029] According to a specific embodiment of the present invention, the method further comprises step 5), injecting water as a displacement plug.

[0030] According to a specific embodiment of the present invention, the total injection volume of the leading slug, the main body slug, the trailing slug, the sealing slug and the replacement slug is calculated as 100%, the injection volume of the leading slug accounts for 2 to 6%, the injection volume of the main body slug accounts for 30 to 34%, the injection volume of the trailing slug accounts for 20 to 24%, the injection volume of the sealing slug accounts for 10 to 14% and the injection volume of the replacement slug accounts for 22 to 38%.

[0031] In the bottom water shielding method provided by the present invention, the injection speed of each slug and the total injection volume of the front slug, the main slug, the rear slug and the sealing slug can be determined according to the actual situation of on-site construction.

[0032] The bottom water shielding system according to one of the present inventions or the bottom water shielding method according to the second present invention is used in shielding bottom water in a cave-type reservoir.

[0033] Beneficial effects of the present invention:

[0034] In view of the problem that the prior art lacks a high-strength bottom water shielding method for cave-type reservoirs, the present invention provides a bottom water shielding system and a bottom water shielding method. The bottom water shielding system includes a dilution-resistant jelly system, a mineral powder jelly system and a high-temperature gel system. The bottom water shielding method provided by the present invention adopts the bottom water shielding system to perform bottom water shielding in the form of a segment plug combination, specifically: the dilution-resistant jelly system is injected into the ground as a front segment plug to enhance the adhesion of subsequent segment plugs along the way; the mineral powder jelly system is injected into the ground as a main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range; the dilution-resistant jelly system is injected into the ground as a rear segment plug to enhance the shielding effect of the main segment plug and plug the cracks around the well; the high-temperature gel system is injected as a sealing segment plug to prevent the front segment plug, the main segment plug and the rear segment plug from spitting back, thereby reducing the damage to the tubing in the well. The bottom water shielding system and bottom water shielding method provided by the present invention have been actually applied in high water-content wells with a water content of 70% to 98% in karst-type reservoirs. After treatment, the daily production of TKX1 well, TKX2 well and TKX3 well are as follows: the daily oil production increases from 1.3t, 4.0t and 0.9t before treatment to 12.6t, 15.0t and 14.1t after treatment, respectively; the production continues for 180 days, 150 days and 160 days, respectively; the cumulative oil production increases by 1773.6t, 921.4t and 2196.2t, respectively, and the oil production is still increasing, and the treatment effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The results show that the bottom water shielding system and the bottom water shielding method provided by the present invention were used to treat the TKX1 well in Example 1;

[0036] Figure 2 The present invention is used to treat the TKX2 well in Example 2.

[0037] Figure 3 The result shows that Example 3 uses the bottom water shielding system and the bottom water shielding method provided by the present invention to treat the TKX3 well. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with examples, but the examples of the present invention are only exemplary descriptions, and the implementation methods do not constitute limitations of the present invention under any circumstances.

[0039] One of the present inventions provides a bottom water shielding system, which includes a dilution-resistant jelly system, a mineral powder jelly system and a high-temperature gel system.

[0040] According to a specific embodiment of the present invention, the dilution-resistant gel system comprises polyacrylamide, 2-acrylamide-2-methylpropane sulfonic acid, N-hetero long-chain alkyl acrylamide monomer, deoxidizer, phenol crosslinking agent and aldehyde crosslinking agent; and / or

[0041] The mineral powder jelly system comprises polyvinyl alcohol, polyacrylic acid, phenolic crosslinking agent and bentonite; and / or

[0042] The high temperature gel system comprises water glass and carbon amide;

[0043] Preferably, the mass of the water glass is taken as 100%, wherein the content of sodium silicate is 70wt%;

[0044] Preferably, the water glass is diluted with water in a volume ratio of 1:(1 to 2) (for example, the volume ratio of water glass:water is 1:1, 1:1.5, 1:2).

[0045] According to a specific embodiment of the present invention, the mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.8 to 1 wt% polyacrylamide, 0.6 to 0.8 wt% 2-acrylamide-2-methylpropane sulfonic acid, 0.6 to 0.8 wt% N-hetero long-chain alkyl acrylamide monomer, 0.2 to 0.4 wt% deoxidizer, 0.7 to 0.9 wt% phenol crosslinker, 0.7 to 0.9 wt% aldehyde crosslinker and the balance water.

[0046] According to a specific embodiment of the present invention, the mass of the mineral powder jelly system is calculated as 100%, and the mineral powder jelly system includes 2 to 2.5 wt% polyvinyl alcohol, 1 to 1.5 wt% polyacrylic acid, 9 to 11 wt% phenolic crosslinker, 52 to 54 wt% bentonite and the balance water.

[0047] According to a specific embodiment of the present invention, the mass of the water glass is calculated as 100%, and the amount of the carbonamide is 2 to 3 wt%.

[0048] According to a specific embodiment of the present invention, the mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.8wt% polyacrylamide, 0.6wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.6wt% N-hetero long-chain alkyl acrylamide monomer, 0.2wt% deoxidizer, 0.7wt% phenol crosslinker, 0.7wt% aldehyde crosslinker and the balance water;

[0049] and / or the mass of the mineral powder jelly system is taken as 100%, the mineral powder jelly system comprises 2wt% polyvinyl alcohol, 1wt% polyacrylic acid, 9wt% phenolic crosslinking agent, 52wt% bentonite and the balance water; and / or

[0050] The mass of the water glass is calculated as 100%, and the amount of the carbonamide used is 2 wt %.

[0051] According to a specific embodiment of the present invention, the mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.9wt% polyacrylamide, 0.7wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.7wt% N-hetero long-chain alkyl acrylamide monomer, 0.3wt% deoxidizer, 0.8wt% phenol crosslinker, 0.8wt% aldehyde crosslinker and the balance water;

[0052] and / or the mass of the mineral powder jelly system is taken as 100%, the mineral powder jelly system comprises 2.3wt% polyvinyl alcohol, 1.3wt% polyacrylic acid, 10wt% phenolic crosslinking agent, 53wt% bentonite and the balance water; and / or

[0053] The mass of the water glass is calculated as 100%, and the amount of the carbonamide used is 2.5wt%.

[0054] According to a specific embodiment of the present invention, the mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 1wt% polyacrylamide, 0.8wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.8wt% N-hetero long-chain alkyl acrylamide monomer, 0.4wt% deoxidizer, 0.9wt% phenol crosslinker, 0.9wt% aldehyde crosslinker and the balance water;

[0055] and / or the mass of the mineral powder jelly system is taken as 100%, the mineral powder jelly system comprises 2.5wt% polyvinyl alcohol, 1.5wt% polyacrylic acid, 11wt% phenolic crosslinking agent, 54wt% bentonite and the balance water; and / or

[0056] The mass of the water glass is calculated as 100%, and the amount of the carbonic acid amide is 3wt%.

[0057] According to a specific embodiment of the present invention, the dilution-resistant gel system has a temperature resistance of not less than 130°C and / or a salt resistance of not less than 22×10 4 mg / L; and / or the gelling time at 130℃ is 1.5 to 3h; and / or the gelling strength is not less than Grade H; and / or

[0058] The high temperature gel system has a temperature resistance of not less than 130°C and / or a salt resistance of not less than 22×10 4 mg / L; and / or 130℃ gelling time is 1.5 to 3h and / or gelling strength is H to I grade; and / or

[0059] The mineral powder jelly system has a temperature resistance of not less than 130°C and / or a salt resistance of not less than 22×10 4mg / L; and / or density of 1.15 to 1.18 g / cm 3 ; and / or compressive strength not less than 24MPa.

[0060] In the present invention, gel strength level H and level I are gel strength levels measured by the Sydansk visual code method. Gel strength level H refers to a slightly deformable non-flowing gel, and only the gel surface deforms when flipped; gel strength level I refers to a rigid gel, and the gel surface does not deform when flipped.

[0061] According to a specific embodiment of the present invention, the molecular weight of the polyacrylamide is 2×10 5 ; and / or

[0062] The molecular weight of the N-hetero long-chain alkyl acrylamide monomer is 1×10 4 ; and / or

[0063] The molecular weight of the polyvinyl alcohol is 120,000 to 150,000; and / or

[0064] The molecular weight of the polyacrylic acid is 5000; and / or

[0065] The deoxidizer is thiourea; and / or

[0066] The phenolic cross-linking agent is hydroquinone; and / or

[0067] The aldehyde cross-linking agent is hexamethylenetetramine; and / or

[0068] The phenolic cross-linking agent is a product obtained by condensation of alkylphenol and formaldehyde;

[0069] Preferably, the N-hetero long-chain alkyl acrylamide monomer is purchased from Dongying Dayong Petroleum Additives Co., Ltd.

[0070] The second aspect of the present invention provides a bottom water shielding method, which uses the bottom water shielding system described in the first aspect of the present invention to perform bottom water shielding in a slug combination manner;

[0071] 1) The dilution-resistant gel system is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way;

[0072] 2) The mineral powder jelly system is injected into the ground as the main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range;

[0073] 3) injecting the dilution-resistant gel system into the ground as a post-segment plug to enhance the shielding effect of the main segment plug and seal the cracks around the well;

[0074] 4) Injecting the high temperature gel system as a sealing slug to prevent the front slug, the main slug and the rear slug from spitting back, thereby reducing damage to the tubular string in the well.

[0075] According to a specific embodiment of the present invention, the method further comprises step 5), injecting water as a displacement plug.

[0076] According to a specific embodiment of the present invention, the total injection volume of the leading slug, the main body slug, the trailing slug, the sealing slug and the replacement slug is calculated as 100%, the injection volume of the leading slug accounts for 2 to 6%, the injection volume of the main body slug accounts for 30 to 34%, the injection volume of the trailing slug accounts for 20 to 24%, the injection volume of the sealing slug accounts for 10 to 14% and the injection volume of the sealing slug accounts for 22 to 38%.

[0077] According to a specific embodiment of the present invention, the injection speed of the front slug, the main slug, the rear slug, the sealing slug and the replacement slug is 18 to 30 m / s. 3 / h;

[0078] Preferably, the injection speed of the front slug, main slug, rear slug, sealing slug and displacement slug is 24m / s. 3 / h.

[0079] According to a specific embodiment of the present invention, the total injection volume of the front slug, the main slug, the rear slug and the sealing slug is not more than 600m 3 .

[0080] The bottom water shielding system according to one of the present inventions or the bottom water shielding method according to the second present invention is used in shielding bottom water in a cave-type reservoir.

[0081] The bottom water shielding method provided by the present invention firstly targets the characteristics of strong hydrophilicity and poor adhesion of the long-term water channel of the cave-type reservoir, and injects a dilution-resistant jelly system as a front plug into the ground to improve the adsorption capacity of the crack cave wall of the cave-type reservoir, enhance the adhesion of the subsequent slugs, and play a supporting and plugging role for the subsequent slugs; then, a mineral powder jelly system is injected into the ground as the main slug. After the mineral powder jelly is formed under the action of the formation temperature and pressure, it can form a high-strength plugging layer on the basis of the supporting and plugging of the front slug, play a greater shielding role, block the bottom water source with a larger cave range, effectively suppress the strength of the bottom water, slow down the rise and breakthrough of the bottom water, and expand the scope of the plugging. Then, the dilution-resistant gel system is injected into the ground as the rear slug, which is deployed near the wellbore and formed under the action of formation temperature and pressure, so as to further strengthen the plugging of cracks around the wellbore and enhance the shielding effect of the main slug, which can slow down the rising speed of bottom water and reduce the water shielding pressure difference, which is conducive to the recovery of the remaining oil around the wellbore; then, the high-temperature gel system is injected into the ground as the sealing slug to prevent the previously injected front slug, middle slug and rear slug from spitting back, and reduce the damage to the tubing in the well; finally, water is preferably injected into the ground as the displacement slug. The injection of the displacement slug can enhance the bottom water shielding effect of the aforementioned slug and avoid the aforementioned slug being blocked in the well.

[0082] Bottom water shielding system

[0083] The raw material information used in Examples 1 to 3 is as follows:

[0084] Polyacrylamide: purchased from Huaxing Chemical Co., Ltd., Dongying City, Shandong Province, with a molecular weight of 2×10 5 ;

[0085] 2-Acrylamide-2-methylpropanesulfonic acid: purchased from Kanos Technology Co., Ltd., Wuhan, Hubei Province;

[0086] N-hetero long-chain alkyl acrylamide monomer: purchased from Dongying Dayong Petroleum Additives Co., Ltd., with a molecular weight of 1×10 4 ;

[0087] Thiourea: purchased from Xinjiang Haosheng Weiheng Chemical Co., Ltd.;

[0088] Polyvinyl alcohol: purchased from Xinjiang Yue New Energy Chemical Co., Ltd., with medium degree of polymerization and molecular weight of 120,000 to 150,000;

[0089] Polyacrylic acid: purchased from Hubei Xinrunde Chemical Co., Ltd., molecular weight 5000;

[0090] Phenolic crosslinking agent: a water-soluble phenolic crosslinking agent, specifically a product obtained by condensation of alkylphenol and formaldehyde aqueous solution, purchased from Liaoning Panjin Yanghui Technology Co., Ltd.;

[0091] Bentonite: purchased from Tianshan Bentonite Processing Plant in Toksun County, Xinjiang, CAS No. 1302-78-9;

[0092] Water glass: Sodium silicate accounts for about 70% of the total mass and is purchased from Hunan Yueyang Tianying Chemical Co., Ltd.;

[0093] Carbon amide: purchased from Xinjiang Tianye Co., Ltd.

[0094] Example 1

[0095] The bottom water shielding system provided in this embodiment is as follows:

[0096] (1) Dilution-resistant gel system: The mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.8wt% polyacrylamide, 0.6wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.6wt% N-hetero long-chain alkyl acrylamide monomer, 0.2wt% deoxidizer thiourea, 0.7wt% phenol crosslinking agent hydroquinone, 0.7wt% aldehyde crosslinking agent hexamethylenetetramine and the balance water; the above components are weighed according to proportion, mixed, and stirred to obtain a dilution-resistant gel system;

[0097] (2) Mineral powder jelly system: The total mass of the mineral powder jelly system is 100%, and the mineral powder jelly system includes 2wt% of reinforcing agent polyvinyl alcohol, 1wt% of suspending agent polyacrylic acid, 9wt% of phenolic crosslinking agent, 52wt% of bentonite and the balance of water; the above components are weighed according to proportion, mixed and stirred evenly to obtain the mineral powder jelly system;

[0098] (3) High temperature gel system: dilute water glass with clean water (the volume ratio of water glass: water is 1:1), add carbonamide, and the amount of carbonamide is 2wt% of the mass of water glass; weigh the above components according to proportion, mix them, and stir them evenly to obtain a high temperature gel system.

[0099] Example 2

[0100] The bottom water shielding system provided in this embodiment is as follows:

[0101] (1) Dilution-resistant gel system: The mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.9wt% polyacrylamide, 0.7wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.7wt% N-hetero long-chain alkyl acrylamide monomer, 0.3wt% deoxidizer thiourea, 0.8wt% phenol crosslinking agent hydroquinone, 0.8wt% aldehyde crosslinking agent hexamethylenetetramine and the balance water; the above components are weighed according to proportion, mixed, and stirred to obtain a dilution-resistant gel system;

[0102] (2) Mineral powder jelly system: The total mass of the mineral powder jelly system is 100%, and the mineral powder jelly system includes 2.3wt% of reinforcing agent polyvinyl alcohol, 1.3wt% of suspending agent polyacrylic acid, 10wt% of phenolic crosslinking agent, 53wt% of bentonite and the balance of water; the above components are weighed according to proportion, mixed and stirred evenly to obtain the mineral powder jelly system;

[0103] (3) High temperature gel system: dilute water glass with clean water (the volume ratio of water glass: water is 1:1.5), add carbonamide, and the amount of carbonamide is 2.5wt% of the mass of water glass; weigh the above components according to proportion, mix them, and stir them evenly to obtain a high temperature gel system.

[0104] Example 3

[0105] The bottom water shielding system provided in this embodiment is as follows:

[0106] (1) Dilution-resistant gel system: The mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 1.0 wt% polyacrylamide, 0.8 wt% 2-acrylamide-2-methylpropanesulfonic acid, 0.8 wt% N-hetero long-chain alkyl acrylamide monomer, 0.4 wt% thiourea as a deoxidizer, 0.9 wt% hydroquinone as a phenolic crosslinking agent, 0.9 wt% urotropine as an aldehyde crosslinking agent, and the balance of water; the above components are weighed according to proportion, mixed, and stirred to obtain a dilution-resistant gel system;

[0107] (2) Mineral powder jelly system: The mass of the mineral powder jelly system is calculated as 100%, and the mineral powder jelly system includes 2.5wt% of reinforcing agent polyvinyl alcohol, 1.5wt% of suspending agent polyacrylic acid, 11wt% of phenolic crosslinking agent, 54wt% of bentonite and the balance of water; the above components are weighed according to proportion, mixed and stirred evenly to obtain the mineral powder jelly system;

[0108] (3) High temperature gel system: dilute water glass with clean water (the volume ratio of water glass: water is 1:2), add carbonamide, and the amount of carbonamide is 3wt% of the mass of water glass; weigh the above components according to proportion, mix them, and stir them evenly to obtain a high temperature gel system.

[0109] Test Example 1-Bottom Water Shielding System Performance Evaluation

[0110] At room temperature, the mineralization degree was 22×10 4 The raw materials were weighed according to the dosage ratio of each component recorded in Examples 1 to 3 with a simulated formation water of 100 mg / L, and each raw material was completely dissolved in the simulated formation water to obtain dilution-resistant gel-1, mineral powder gel-1, high-temperature gel-1, dilution-resistant gel-2, mineral powder gel-2, high-temperature gel-2, dilution-resistant gel-3, mineral powder gel-3, and high-temperature gel-3 for testing in turn;

[0111] A. Determination of gelling time and gelling strength: 30 g of the dilution-resistant gel and high-temperature gel prepared in this test example were weighed and placed in a thermostat set at 130° C. for aging. During the aging process, the gelling conditions of the dilution-resistant gel and high-temperature gel were observed. The gelling time and gelling strength of the dilution-resistant gel and high-temperature gel were measured according to the Sydansk visual code method. The results are shown in Table 1.

[0112] B. Determination of dehydration rate at high temperature for 90 days: 30 g of the dilution-resistant jelly and high-temperature gel prepared in this test example were weighed, placed in containers respectively, sealed, and then aged in a constant temperature box set at 130°C; after gelation, continued aging at 130°C, and after the aging time reached 90 days, the dehydration amount of the dilution-resistant jelly and high-temperature gel was observed by visual inspection, and the dehydration amount was divided by the volume of the dilution-resistant jelly or high-temperature gel after gelation to obtain the dehydration rate. The results are shown in Table 1;

[0113] C. Determination of density of mineral powder jelly: The density of mineral powder jelly-1 to mineral powder jelly-3 prepared in this test example was measured using a digital liquid density meter. The results are shown in Table 2.

[0114] D. Determination of compressive strength of mineral powder jelly: Take 30g of each mineral powder jelly prepared in this test, cure it at 130℃ and 20MPa for 24h, and use a compressive strength tester to measure the compressive strength of the mineral powder jelly after gelation. The results are shown in Table 2.

[0115] Table 1. Resistance to dilution gel and high temperature gel performance

[0116]

[0117]

[0118] Table 2. Mineral powder jelly properties

[0119] Example Gel No. density Compressive strength Example 1 Mineral powder jelly-1 <![CDATA[1.15g / cm 3 ]]> >24MPa Example 2 Mineral powder jelly-2 <![CDATA[1.17g / cm 3 ]]> >26MPa Example 3 Mineral powder jelly-3 <![CDATA[1.18g / cm 3 ]]> >27MPa

[0120] According to the data in Tables 1 and 2, the bottom water shielding system provided by the present invention has suitable gelation time, density, sufficient gelation strength and compressive strength, and the dehydration rate after aging for 90 days at 130°C can reach less than 10%, and the high temperature stability is good, which meets the requirements of bottom water shielding of cave-type reservoirs.

[0121] Implementing bottom water shielding methods

[0122] During the development of cavernous reservoirs, 40 out of 98 wells had high water content problems ranging from 70% to 98%, accounting for 40.82% of the wells. The bottom water shielding system and bottom water shielding method provided by the present invention are used to treat the high water content wells, and the following is a detailed description taking Well TKX1, Well TKX2 and Well TKX3 as examples.

[0123] Example 4

[0124] Using the bottom water shielding system provided in Example 1, the bottom water shielding method provided by the present invention was implemented on the TKX1 well, and the construction was carried out by the fixed pipe string reverse injection method. The specific steps are as follows:

[0125] 1) The dilution-resistant gel system provided in Example 1 is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way;

[0126] 2) The mineral powder jelly system provided in Example 1 is injected into the ground as the main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range;

[0127] 3) injecting the dilution-resistant gel system provided in Example 1 into the ground as a post-slug to enhance the shielding effect of the main slug and seal the cracks around the well;

[0128] 4) injecting the high temperature gel system provided in Example 1 as a sealing slug to prevent the front slug, the main slug and the rear slug from vomiting back, thereby reducing the damage to the tubing string in the well;

[0129] 5) Inject oilfield water as a displacement plug, and after the well is soaked, it will start to flow and produce automatically;

[0130] During the construction process, the injection speed of each segment plug was 18m 3 / h, cumulative injection 400m 3 , the injection volume of the front slug accounts for 2%, and the cumulative injection volume is 8m 3 The main slug injection volume accounts for 30%, and the cumulative injection volume is 120m 3 The injection volume of the rear slug accounts for 20%, and the cumulative injection volume is 80m 3 The injection volume of the sealing plug accounts for 10%, and the cumulative injection volume is 40m 3 , the total amount of oilfield water injected is 152m 3 .

[0131] Figure 1 The treatment of the TKX1 well in this embodiment is shown. It can be seen that after treatment, the TKX1 well produces 18.2 tons of liquid per day, and the daily oil production increases from 1.3 tons before treatment to 12.6 tons after treatment, with a water content of 31.0%. At present, the well has been in continuous production for 180 days, with a cumulative increase of 1773.6 tons of oil, and is still increasing oil.

[0132] Example 5

[0133] Using the bottom water shielding system provided in Example 2, the bottom water shielding method provided by the present invention was implemented on the TKX2 well, and the construction was carried out by the fixed pipe string reverse injection method. The specific steps are as follows:

[0134] 1) The dilution-resistant gel system provided in Example 2 is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way;

[0135] 2) The mineral powder jelly system provided in Example 2 is injected into the ground as the main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range;

[0136] 3) The dilution-resistant gel system provided in Example 2 is injected into the ground as a post-slug to enhance the shielding effect of the main slug and seal the cracks around the well;

[0137] 4) injecting the high temperature gel system provided in Example 2 as a sealing slug to prevent the front slug, the main slug and the rear slug from vomiting back, thereby reducing the damage to the tubing string in the well;

[0138] 5) Inject oilfield water as a displacement plug, and after the well is soaked, it will start to flow and produce automatically;

[0139] During the construction process, the injection speed of each segment plug was 24m 3 / h, cumulative injection 500m 3 , the injection volume of the front slug accounts for 4%, and the cumulative injection volume is 20m 3 The injection volume of the main slug accounts for 32%, and the cumulative injection volume is 160m 3 The injection volume of the rear slug accounts for 22%, and the cumulative injection volume is 110m 3 The injection volume of the sealing plug accounts for 12%, and the cumulative injection volume is 60m 3 , oilfield water has been injected 150m 3 .

[0140] Figure 2 The treatment of the TKX2 well in this embodiment is shown. It can be seen that after treatment, the TKX2 well produces 17.2 tons of liquid per day, and the daily oil production increases from 4.0 tons before treatment to 15.0 tons after treatment, with a water content of 12.9%. At present, the well has been in continuous production for 150 days, with a cumulative increase of 921.4 tons of oil, and is still increasing oil.

[0141] Example 6

[0142] Using the bottom water shielding system provided in Example 3, the bottom water shielding method provided by the present invention was implemented on the TKX3 well, and the construction was carried out by the fixed pipe string reverse injection method. The specific steps are as follows:

[0143] 1) The dilution-resistant gel system provided in Example 3 is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way;

[0144] 2) The mineral powder jelly system provided in Example 3 is injected into the ground as the main segment plug to play a shielding role, delay the breakthrough of bottom water, and expand the plugging range;

[0145] 3) injecting the dilution-resistant gel system provided in Example 3 into the ground as a post-segment plug to enhance the shielding effect of the main segment plug and seal the cracks around the well;

[0146] 4) injecting the high temperature gel system provided in Example 3 as a sealing slug to prevent the front slug, the main slug and the rear slug from vomiting back, thereby reducing the damage to the tubing string in the well;

[0147] 5) Inject oilfield water as a displacement plug, and after the well is soaked, it will start to flow and produce automatically;

[0148] During the construction process, the injection speed of each segment plug is 30m 3 / h, cumulative injection 600m 3 The injection volume of the front slug accounts for 6%, and the cumulative injection volume is 36m 3 The injection volume of the main slug accounts for 34%, and the cumulative injection volume is 204m 3 The injection volume of the rear slug accounts for 24%, and the cumulative injection volume is 144m 3 The injection volume of the sealing segment plug accounts for 14%, and the cumulative injection volume is 84m 3 , the total amount of oilfield water injected is 132m 3 .

[0149] Figure 3 The treatment of the TKX3 well in this embodiment is shown. It can be seen that after treatment, the TKX3 well produces 29.1 tons of liquid per day, and the daily oil production increases from 0.9 tons before treatment to 14.1 tons after treatment, with a water content of 51.6%. At present, the well has been in continuous production for 160 days, with a cumulative increase of 2196.2 tons of oil, and is still increasing oil.

[0150] Although the present invention has been described with reference to specific embodiments, it will be appreciated by those skilled in the art that various changes may be made without departing from the true spirit and scope of the present invention. In addition, the subject matter, spirit and scope of the present invention may be varied to accommodate specific situations, materials, material combinations and methods. All of these changes are included within the scope of the claims of the present invention.

Claims

1. A bottom water shielding system, comprising a dilution-resistant jelly system, a mineral powder jelly system and a high-temperature gel system.

2. The bottom water shielding system according to claim 1, It is characterized in that The dilution-resistant gel system comprises polyacrylamide, 2-acrylamide-2-methylpropane sulfonic acid, N-hetero long-chain alkyl acrylamide monomer, deoxidizer, phenol crosslinking agent and aldehyde crosslinking agent; and / or The mineral powder jelly system comprises polyvinyl alcohol, polyacrylic acid, phenolic crosslinking agent and bentonite; and / or The high temperature gel system comprises water glass and carbon amide.

3. The bottom water shielding system according to claim 2, It is characterized in that The mass of the dilution-resistant gel system is calculated as 100%, and the dilution-resistant gel system includes 0.8 to 1 wt % of polyacrylamide, 0.6 to 0.8 wt % of 2-acrylamide-2-methylpropane sulfonic acid, 0.6 to 0.8 wt % of N-hetero long-chain alkyl acrylamide monomer, 0.2 to 0.4 wt % of deoxidizer, 0.7 to 0.9 wt % of phenol crosslinker, 0.7 to 0.9 wt % of aldehyde crosslinker and the balance of water.

4. The bottom water shielding system according to claim 2, It is characterized in that The mass of the mineral powder jelly system is calculated as 100%, and the mineral powder jelly system includes 2 to 2.5 wt % of polyvinyl alcohol, 1 to 1.5 wt % of polyacrylic acid, 9 to 11 wt % of phenolic crosslinking agent, 52 to 54 wt % of bentonite and the balance of water.

5. The bottom water shielding system according to claim 2, It is characterized in that The mass of the water glass is taken as 100%, and the amount of the carbonic acid amide is 2 to 3 wt %.

6. The bottom water shielding system according to any one of claims 2 to 5, It is characterized in that The molecular weight of the polyacrylamide is 2×10 5 ; and / or The molecular weight of the N-hetero long-chain alkyl acrylamide monomer is 1×10 4 ; and / or The molecular weight of the polyvinyl alcohol is 120,000 to 150,000; and / or The molecular weight of the polyacrylic acid is 5000; and / or The deoxidizer is thiourea; and / or The phenolic cross-linking agent is hydroquinone; and / or The aldehyde cross-linking agent is hexamethylenetetramine; and / or The phenolic crosslinking agent is a product obtained by condensation of alkylphenol and formaldehyde.

7. A bottom water shielding method, It is characterized in that Using the bottom water shielding system according to any one of claims 1 to 6, bottom water shielding is performed in a slug combination manner; 1) The dilution-resistant gel system is injected into the ground as a pre-slug to enhance the adhesion of subsequent slugs along the way; 2) The mineral powder jelly system is injected into the ground as the main segment plug to play a shielding role, delay bottom water breakthrough, and expand the plugging range; 3) injecting the dilution-resistant gel system into the ground as a post-segment plug to enhance the shielding effect of the main segment plug and seal the cracks around the well; 4) Injecting the high temperature gel system as a sealing slug to prevent the front slug, the main slug and the rear slug from spitting back, thereby reducing damage to the tubular string in the well.

8. The method according to claim 7, It is characterized in that The method further comprises step 5), injecting water as a displacement plug.

9. The method according to claim 8, It is characterized in that Taking the total injection volume of the leading slug, the main body slug, the trailing slug, the sealing slug and the displacement slug as 100%, the injection volume of the leading slug accounts for 2 to 6%, the injection volume of the main body slug accounts for 30 to 34%, the injection volume of the trailing slug accounts for 20 to 24%, the injection volume of the sealing slug accounts for 10 to 14% and the injection volume of the displacement slug accounts for 22 to 38%.

10. Use of the bottom water shielding system according to any one of claims 1 to 6 or the bottom water shielding method according to any one of claims 7 to 9 in shielding bottom water in a cave-type reservoir.

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