Water plugging system and high-angle fracture deep source plugging method

Abstract

The application provides a water plugging system and a high-angle fracture deep source control water plugging method. The water plugging system comprises a dilution-resistant gel system, a weighted gel system, a high-temperature gel system and a high-temperature gel system. The high-angle fracture deep source control plugging method uses the water plugging system as a water plugging agent, and carries out water plugging in a slug combination mode, so that the treatment effect of high water cut wells of a fracture-vug type reservoir is remarkable.

Description

Technical Field

[0001] This invention belongs to the field of water shut-off and extraction technology for fractured-vuggy reservoirs, and particularly relates to a water shut-off system and a method for suppressing water sources and shutting off water in deep high-angle fractures. Background Technology

[0002] Fractured-vuggy reservoirs are well-developed with confirmed oil and gas injection. However, due to strong bottom water capacity, even after switching to pumping and increasing the production pressure differential, mechanical pumping remains ineffective, resulting in persistently high water cut. This leads to the remaining oil concentrating at the top. Static characterization of the reservoir indicates the presence of high-angle fractures, and water drive curves show rapid flooding of deep bottom water along these high-angle fractures. These high-angle fractures within the fractures are the primary water inflow channels. Previous water-blocking slugs using heat-resistant gels and resistant gels were primarily designed for wells with weak bottom water capacity, operating only on peri-well fractures and unable to migrate to deeper areas to suppress bottom water sources. Their effectiveness in sealing strong bottom water in high-angle fractures at the bottom of the reservoir is limited. Although there is considerable research and development of reagents and slugs for deep water shut-off, the following problems still exist:

[0003] (1) Existing technologies mainly focus on the research and development of deep water-blocking agents and the evaluation of indoor test systems. No field application of deep water-blocking agents has been observed, and the combination of their slugs is also unclear.

[0004] (2) Existing water-blocking plugs are mainly suitable for deep water blocking in sandstone, and have poor adaptability to blocking strong bottom water in high-angle fractures of carbonate rock fracture-vuggy reservoirs.

[0005] (3) Existing water-blocking sluices generally have the problem of low blocking strength, and the blocking range and blocking strength are relatively small for strong bottom water.

[0006] In conclusion, there is an urgent need to develop a deep water source suppression and shut-off method for high-angle fractures in fractured-vuggy reservoirs, in order to improve the current situation of high water cut in oil wells and provide support for improving the recovery rate of fractured-vuggy reservoirs. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a deep water source suppression and plugging method for high-angle fractures in fractured-vuggy reservoirs, thereby improving the high water cut status of oil wells and providing support for enhancing the recovery rate of fractured-vuggy reservoirs.

[0008] To achieve the above objectives, the first aspect of the present invention provides a water-blocking system, which includes a dilution-resistant gel system, a weighted gel system, a high-temperature gel system, and a high-temperature gel system.

[0009] According to a specific embodiment of the present invention, the dilution-resistant gel system comprises a first anionic polyacrylamide, a first polyurethane, hydroxypropyl methylcellulose, a first phenolic crosslinking agent, and a first aldehyde crosslinking agent; and / or

[0010] The weighted gel system includes a second anionic polyacrylamide, hydroxypropyl starch, a phenolic crosslinking agent, and a weighting agent; and / or the high-temperature gel system includes a third anionic polyacrylamide, a second polyurethane, a second phenolic crosslinking agent, and a second aldehyde crosslinking agent; and / or

[0011] The high-temperature gel system includes water glass and carbamide.

[0012] According to a specific embodiment of the present invention, the total mass of the dilution-resistant gel system is 100%, the dilution-resistant gel system includes 0.6 to 1 wt% of the first anionic polyacrylamide, 0.4 to 1 wt% of the first polyurethane, 0.2 to 0.6 wt% of hydroxypropyl methylcellulose, 0.2 to 0.6 wt% of the first phenolic crosslinking agent, 0.2 to 0.6 wt% of the first aldehyde crosslinking agent and the balance being water.

[0013] According to a specific embodiment of the present invention, the weighted gel system is taken as 100% by mass, and the weighted gel system includes 0.6 to 1 wt% of the second anionic polyacrylamide, 0.6 to 1 wt% of hydroxypropyl starch, 0.2 to 0.6 wt% of phenolic crosslinking agent, 10 to 15 wt% of weighting agent and the balance being water.

[0014] According to a specific embodiment of the present invention, the high-temperature gel system is taken as 100% by mass, and the high-temperature gel system comprises 0.6 to 1 wt% of the third anionic polyacrylamide, 0.4 to 1 wt% of the second polyurethane, 0.2 to 0.6 wt% of the second phenolic crosslinking agent, 0.2 to 0.6 wt% of the second aldehyde crosslinking agent, and the balance being water; and / or

[0015] The water glass is taken as 100% by mass, and the amount of carbonamide is 2 to 4 wt%.

[0016] According to a specific embodiment of the present invention, the weight-average molecular weight of the first anionic polyacrylamide is 12 × 10⁻⁶. 4 ; and / or the weight-average molecular weight of the second anionic polyacrylamide is 10 × 10⁻⁶. 4 ; and / or the weight-average molecular weight of the third anionic polyacrylamide is 15 × 10⁻⁶. 4 ; and / or

[0017] The weight-average molecular weight of the first polyurethane and the weight-average molecular weight of the second polyurethane are both 5500; and / or

[0018] The first phenolic crosslinking agent and the second phenolic crosslinking agent are hydroquinone; and / or

[0019] The first aldehyde crosslinking agent and the second aldehyde crosslinking agent are hexamethylenetetramine; and / or

[0020] The phenolic crosslinking agent is a product obtained by the condensation of naphthol and formaldehyde; and / or

[0021] The weighting agent is potassium chloride.

[0022] The second aspect of this invention provides a method for suppressing water sources and plugging water in deep high-angle cracks, using the water-plugging system described in the first aspect of this invention as the water-plugging agent, and plugging water in a slug combination manner;

[0023] 1) The dilution-resistant gel system is used as a pre-slug, injected underground, and adheres to the path of the subsequent slugs to play a blocking role;

[0024] 2) Using the aforementioned weighted gel system as an intermediate plug, it is injected underground to seal deep bottom water and suppress the intensity of strong bottom water;

[0025] 3) Inject the high-temperature gel system as a post-slug for near-wellbore sealing to expand the sealing range;

[0026] 4) Inject the high-temperature gel system as a sealing plug to prevent the front plug, intermediate plug and rear plug from backflowing and clogging the wellbore.

[0027] In this invention, high-angle fractures refer to formation fractures with an angle between 45° and 70° with respect to the well axis.

[0028] In this invention, bottom water refers to the water that fills the bottom of oil and gas and supports the oil and gas in oilfield production; strong bottom water refers to bottom water with strong energy and a water volume ratio greater than 30.

[0029] According to a specific embodiment of the present invention, the method further includes step 5), injecting water as a replacement slug.

[0030] According to a specific embodiment of the present invention, the total injection volume of the pre-segment plug, intermediate segment plug, rear segment plug, sealing segment plug, and displacement segment plug is taken as 100%, wherein the injection volume of the pre-segment plug accounts for 4 to 8%, the injection volume of the intermediate segment plug accounts for 25 to 30%, the injection volume of the rear segment plug accounts for 30 to 36%, the injection volume of the sealing segment plug accounts for 10 to 16%, and the injection volume of the displacement segment plug accounts for 10 to 31%.

[0031] In the bottom water shielding method provided by this invention, the injection rate of each segment plug and the total injection volume of the front segment plug, the middle segment plug, the rear segment plug and the sealing segment plug can also be determined according to the actual situation of the on-site construction.

[0032] Application of the water shut-off system described in the first aspect of the present invention or the water shut-off method for deep high-angle fractures described in the second aspect of the present invention in water shut-off of fractured-vuggy reservoirs.

[0033] The beneficial effects of this invention are:

[0034] To address the problem that existing deep water-plugging agents and slugs are ineffective at sealing high-angle fractures in fractured-vuggy reservoirs, this invention provides a water-plugging system and a method for suppressing and plugging deep water sources in high-angle fractures. The water-plugging system includes a dilution-resistant gel system, a weighted gel system, a high-temperature gel system, and a high-temperature gel system. The method for suppressing and plugging deep water sources in high-angle fractures uses the water-plugging system as the water-plugging agent and performs water plugging in a slug combination manner. Specifically, the dilution-resistant gel system is used as a pre-plug to support subsequent slugs; the weighted gel system is used as an intermediate slug to seal deep bottom water and suppress its intensity; the high-temperature gel system is used as a post-plug to seal near-wellbore to expand the sealing range; the high-temperature gel system is used as a sealing slug to prevent the pre-plug, intermediate, and post-plugs from backflowing and clogging the wellbore; and finally, water is preferably injected as a replacement slug. The intermediate and post-slug plugs work together to seal the bottom water from far to near, inhibiting its rise and facilitating the extraction of remaining crude oil. The water-blocking system and deep water-suppression method for high-angle fractures provided by this invention have been practically applied in high-water-cut wells with a water cut of 70% to 98% in fractured-vuggy reservoirs. After treatment, the production of wells TPX1, TPX2, and TPX3 is as follows: daily oil production increased from 3.1t, 0.8t, and 0t before treatment to 13.5t, 8.5t, and 11.1t after treatment; continuous production for 190 days, 180 days, and 200 days; and cumulative oil increases of 1419.3t, 1489.6t, and 583.6t respectively, all still showing continuous increases, demonstrating significant treatment effects. Attached Figure Description

[0035] Figure 1 This reflects the treatment of well TPX1 using the water-blocking system and deep water-suppression method for high-angle fractures provided in Example 1;

[0036] Figure 2 This reflects the treatment of the TPX2 well using the water-blocking system and the deep source suppression and water-blocking method for high-angle fractures provided by the present invention in Example 2;

[0037] Figure 3 This reflects the treatment of the TPX3 well using the water-blocking system and the deep source suppression and water-blocking method for high-angle fractures provided by the present invention in Example 3. Detailed Implementation

[0038] The present invention will be further described below with reference to the embodiments. However, the embodiments of the present invention are merely illustrative examples and should not be construed as limiting the present invention under any circumstances.

[0039] The first aspect of the present invention provides a water-blocking system, which includes a dilution-resistant gel system, a weighted gel system, a high-temperature gel system, and a high-temperature gel system.

[0040] According to a specific embodiment of the present invention, the dilution-resistant gel system comprises a first anionic polyacrylamide, a first polyurethane, hydroxypropyl methylcellulose, a first phenolic crosslinking agent, and a first aldehyde crosslinking agent; and / or

[0041] The weighted gel system includes a second anionic polyacrylamide, hydroxypropyl starch, a phenolic crosslinking agent, and a weighting agent; and / or the high-temperature gel system includes a third anionic polyacrylamide, a second polyurethane, a second phenolic crosslinking agent, and a second aldehyde crosslinking agent; and / or

[0042] The high-temperature gel system includes water glass and carbamide;

[0043] Preferably, the water glass is 100% by mass, wherein the sodium silicate content is 70 wt%.

[0044] Preferably, the water glass is diluted with water at a volume ratio of 1:(1 to 2) (e.g., the volume ratio of water glass to water is 1:1, 1:1.5, or 1:2).

[0045] According to a specific embodiment of the present invention, the total mass of the dilution-resistant gel system is 100%, the dilution-resistant gel system includes 0.6 to 1 wt% of the first anionic polyacrylamide, 0.4 to 1 wt% of the first polyurethane, 0.2 to 0.6 wt% of hydroxypropyl methylcellulose, 0.2 to 0.6 wt% of the first phenolic crosslinking agent, 0.2 to 0.6 wt% of the first aldehyde crosslinking agent and the balance being water.

[0046] According to a specific embodiment of the present invention, the weighted gel system is taken as 100% by mass, and the weighted gel system includes 0.6 to 1 wt% of the second anionic polyacrylamide, 0.6 to 1 wt% of hydroxypropyl starch, 0.2 to 0.6 wt% of phenolic crosslinking agent, 10 to 15 wt% of weighting agent and the balance being water.

[0047] According to a specific embodiment of the present invention, the high-temperature gel system is taken as 100% by mass, and the high-temperature gel system comprises 0.6 to 1 wt% of the third anionic polyacrylamide, 0.4 to 1 wt% of the second polyurethane, 0.2 to 0.6 wt% of the second phenolic crosslinking agent, 0.2 to 0.6 wt% of the second aldehyde crosslinking agent, and the balance being water; and / or

[0048] The water glass is taken as 100% by mass, and the amount of carbonamide is 2 to 4 wt%.

[0049] According to a specific embodiment of the present invention, the total mass of the dilution-resistant gel system is taken as 100%, and the dilution-resistant gel system comprises 0.6 wt% of the first anionic polyacrylamide, 0.4 wt% of the first polyurethane, 0.2 wt% of hydroxypropyl methylcellulose, 0.2 wt% of the first phenolic crosslinking agent, 0.2 wt% of the first aldehyde crosslinking agent, and the balance being water; and / or

[0050] The weighted gel system is taken as 100% by mass, and the weighted gel system includes 0.6 wt% of the second anionic polyacrylamide, 0.6 wt% of hydroxypropyl starch, 0.2 wt% of phenolic crosslinking agent, 10 wt% of weighting agent and the balance being water;

[0051] And / or the high-temperature gel system is taken as 100% by mass, the high-temperature gel system comprising 0.6 wt% of the third anionic polyacrylamide, 0.4 wt% of the second polyurethane, 0.2 wt% of the second phenolic crosslinking agent, 0.2 wt% of the second aldehyde crosslinking agent and the balance being water; and / or

[0052] The water glass is taken as 100% by mass, and the amount of carbonamide is 2 wt%.

[0053] According to a specific embodiment of the present invention, the total mass of the dilution-resistant gel system is taken as 100%, and the dilution-resistant gel system comprises 0.8 wt% of the first anionic polyacrylamide, 0.6 wt% of the first polyurethane, 0.4 wt% of hydroxypropyl methylcellulose, 0.4 wt% of the first phenolic crosslinking agent, 0.4 wt% of the first aldehyde crosslinking agent, and the balance being water; and / or

[0054] The weighted gel system is taken as 100% by mass, and the weighted gel system includes 0.8 wt% of the second anionic polyacrylamide, 0.8 wt% of hydroxypropyl starch, 0.4 wt% of phenolic crosslinking agent, 12 wt% of weighting agent and the balance being water;

[0055] And / or the high-temperature gel system is taken as 100% by mass, the high-temperature gel system comprising 0.8 wt% of the third anionic polyacrylamide, 0.6 wt% of the second polyurethane, 0.4 wt% of the second phenolic crosslinking agent, 0.4 wt% of the second aldehyde crosslinking agent and the balance being water; and / or

[0056] The water glass is taken as 100% by mass, and the amount of carbonamide is 3 wt%.

[0057] According to a specific embodiment of the present invention, the total mass of the dilution-resistant gel system is taken as 100%, the dilution-resistant gel system comprising 1 wt% of the first anionic polyacrylamide, 1 wt% of the first polyurethane, 0.6 wt% of hydroxypropyl methylcellulose, 0.6 wt% of the first phenolic crosslinking agent, 0.6 wt% of the first aldehyde crosslinking agent, and the balance being water; and / or

[0058] The weighted gel system is taken as 100% by mass, and the weighted gel system comprises 1 wt% of the second anionic polyacrylamide, 1 wt% of hydroxypropyl starch, 0.6 wt% of phenolic crosslinking agent, 15 wt% of weighting agent, and the balance being water; and / or

[0059] The high-temperature gel system, by mass, comprises 1 wt% of the third anionic polyacrylamide, 1 wt% of the second polyurethane, 0.6 wt% of the second phenolic crosslinking agent, 0.6 wt% of the second aldehyde crosslinking agent, and the balance being water; and / or

[0060] The water glass is taken as 100% by mass, and the amount of carbonamide is 4 wt%.

[0061] 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 20 × 10⁻⁶. 4 mg / L; and / or gelation time at 130℃ less than 2h; and / or gelation strength not less than H grade; and / or

[0062] The weighted gel system has a temperature resistance of not less than 130℃ and / or a salt resistance of not less than 20×10⁻⁶. 4 mg / L; and / or a density of 1.16 to 1.2 g / cm³ 3 ; and / or a gelation time of 1 to 2 hours at 130°C and / or a gel strength of H to I grade; and / or

[0063] The high-temperature gel system has a temperature resistance of not less than 130℃ and / or a salt resistance of not less than 20×10⁻⁶. 4 mg / L; and / or gelation time at 130℃ for 1 to 3 hours; and / or gel strength not lower than H grade; and / or

[0064] The high-temperature gel system has a gelation time of 1 to 3 hours at 130°C and / or a gel strength of not less than Grade I.

[0065] In this invention, gel strength grades H and I are gel strength levels measured using the Sydansk visual code method. Grade H gel strength refers to a slightly deformable, non-flowing gel, where only the gel surface deforms upon inversion; Grade I gel strength refers to a rigid gel, where the gel surface does not deform upon inversion.

[0066] According to a specific embodiment of the present invention, the weight-average molecular weight of the first anionic polyacrylamide is 12 × 10⁻⁶. 4 ; and / or the weight-average molecular weight of the second anionic polyacrylamide is 10 × 10⁻⁶. 4 ; and / or the weight-average molecular weight of the third anionic polyacrylamide is 15 × 10⁻⁶. 4 ; and / or

[0067] The weight-average molecular weight of the first polyurethane and the weight-average molecular weight of the second polyurethane are both 5500; and / or

[0068] The first phenolic crosslinking agent and the second phenolic crosslinking agent are hydroquinone; and / or

[0069] The first aldehyde crosslinking agent and the second aldehyde crosslinking agent are hexamethylenetetramine; and / or

[0070] The phenolic crosslinking agent is a product obtained by the condensation of naphthol and formaldehyde; and / or

[0071] The weighting agent is potassium chloride.

[0072] Preferably, the CAS number of the hydroxypropyl methylcellulose is 9004-65-3; and / or

[0073] The CAS number of the hydroxypropyl starch is 68584-86-1.

[0074] The second aspect of this invention provides a method for suppressing water sources and plugging water in deep high-angle cracks, using the water-plugging system described in the first aspect of this invention as the water-plugging agent, and plugging water in a slug combination manner;

[0075] 1) The dilution-resistant gel system is used as a pre-slug, injected underground, and adheres to the path of the subsequent slugs to play a blocking role;

[0076] 2) Using the aforementioned weighted gel system as an intermediate plug, it is injected underground to seal deep bottom water and suppress the intensity of strong bottom water;

[0077] 3) Inject the high-temperature gel system as a post-slug for near-wellbore sealing to expand the sealing range;

[0078] 4) Inject the high-temperature gel system as a sealing plug to prevent the front plug, intermediate plug and rear plug from backflowing and clogging the wellbore.

[0079] According to a specific embodiment of the present invention, the method further includes step 5), injecting water as a replacement slug.

[0080] According to a specific embodiment of the present invention, the total injection volume of the pre-segment plug, intermediate segment plug, rear segment plug, sealing segment plug, and displacement segment plug is taken as 100%, wherein the injection volume of the pre-segment plug accounts for 4 to 8%, the injection volume of the intermediate segment plug accounts for 25 to 30%, the injection volume of the rear segment plug accounts for 30 to 36%, the injection volume of the sealing segment plug accounts for 10 to 16%, and the injection volume of the displacement segment plug accounts for 10 to 31%.

[0081] According to a specific embodiment of the present invention, the injection rates of the pre-slug, intermediate slug, post-slug, sealing slug, and displacement slug are independently 18 to 30 m / s. 3 / h;

[0082] Preferably, the injection rate of the pre-plug, intermediate plug, post-plug, sealing plug, and displacement plug is 24 m / s. 3 / h.

[0083] According to a specific embodiment of the present invention, the total injection volume of the pre-plug, intermediate plug, post-plug, and sealing plug is not higher than 300m³. 3 .

[0084] Application of the water shut-off system described in the first aspect of the present invention or the water shut-off method for deep high-angle fractures described in the second aspect of the present invention in water shut-off of fractured-vuggy reservoirs.

[0085] The high-angle fracture deep water source suppression and plugging method provided by this invention first utilizes the characteristics of large volume and strong hydrophilicity of water channeling channels. A dilution-resistant gel system is injected underground as a pre-slug. After injection, the dilution-resistant gel slowly solidifies along its flow path under the influence of formation pressure and temperature, thus supporting the subsequent slugs. Next, a weighted gel system is injected underground as an intermediate slug. Targeting the high-angle fracture system around the well, this intermediate slug can penetrate deep into the high-angle fracture to seal the source of strong bottom water, slowing its rise and laying the foundation for the subsequent slug plugging. Finally, a high-temperature gel system is injected as a post-slug. The plugging process, based on the combined effect of pre-plug and intermediate plugs to suppress deep bottom water sources, involves using high-temperature gel to seal the wellbore fracture system. This, along with the weighted gel from the intermediate plug, further seals the bottom water from far to near, suppressing its intensity and slowing its rise, thus facilitating the extraction of remaining oil in the upper part of the wellbore. Then, a high-temperature gel system is injected as a sealing plug to prevent the injected pre-plug, intermediate plug, and post-plug from being backflowed and sealing the wellbore under the influence of formation water. Finally, water is preferably injected as a displacement plug, which is forced into the formation to further enhance the water-blocking effect of the aforementioned plugs, while also preventing blockage within the wellbore.

[0086] Water blocking system

[0087] The raw material information used in Examples 1 to 3 is as follows:

[0088] The first type of anionic polyacrylamide: anionic polyacrylamide produced by Xinjiang Botianyuan Environmental Protection Materials Co., Ltd., with a molecular weight of 12×10. 4 ;

[0089] Second type of anionic polyacrylamide: Anionic polyacrylamide produced by Henan Hancheng Environmental Protection Co., Ltd., with a molecular weight of 10×10 4 ;

[0090] The third type of anionic polyacrylamide: Anionic polyacrylamide produced by Henan Duohui Chemical Products Co., Ltd., with a molecular weight of 15×10⁻⁶. 4 ;

[0091] First polyurethane and second polyurethane: Polyurethane produced by Guangzhou Haoyi New Material Technology Co., Ltd. of Guangdong Province, with a molecular weight of 5500;

[0092] Hydroxypropyl methylcellulose: Hydroxypropyl methylcellulose produced by Shandong Qingyixin Chemical Technology Co., Ltd., CAS No. 9004-65-3;

[0093] Hydroxypropyl starch: Hydroxypropyl starch produced by Nanjing Songguan Biotechnology Co., Ltd., CAS No. 68584-86-1;

[0094] First phenolic crosslinking agent, second phenolic crosslinking agent: hydroquinone;

[0095] First aldehyde crosslinking agent, second aldehyde crosslinking agent: hexamethylenetetramine;

[0096] Phenolic crosslinking agent: a product obtained by condensation of naphthol and formaldehyde, purchased from Jiangsu Yaohe Chemical Technology Co., Ltd.

[0097] Weighting agent: Potassium chloride produced by Shaanxi Chenming Biotechnology Co., Ltd., CAS No. 7447-40-7;

[0098] Water glass: Sodium silicate content is approximately 70 wt%, produced by Hunan Yueyang Tianying Chemical Co., Ltd.;

[0099] Carbonamide: Produced by Xinjiang Tianye Co., Ltd.

[0100] Example 1

[0101] The water-blocking system provided in this embodiment is as follows:

[0102] (1) Dilution-resistant gel system: The total mass of the dilution-resistant gel system is 100%. The dilution-resistant gel system includes 0.6 wt% of the first anionic polyacrylamide, 0.4 wt% of the first polyurethane, 0.2 wt% of hydroxypropyl methylcellulose, 0.2 wt% of the first phenolic crosslinking agent hydroquinone, 0.2 wt% of the first aldehyde crosslinking agent hexamethylenetetramine, and the balance water. The above components are weighed according to the proportions and mixed and stirred evenly to obtain the dilution-resistant gel system.

[0103] (2) Weighted gel system: The total mass of the weighted gel system is 100%. The weighted gel system includes 0.6 wt% second anionic polyacrylamide, 0.6 wt% hydroxypropyl starch, 0.2 wt% phenolic crosslinking agent, 10 wt% potassium chloride as weighting agent, and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the weighted gel system.

[0104] (3) High-temperature gel system: The total mass of the high-temperature gel system is 100%. The high-temperature gel system includes 0.6% of the third anionic polyacrylamide, 0.4 wt% of the second polyurethane, 0.2 wt% of the second phenolic crosslinking agent hydroquinone, 0.2 wt% of the second aldehyde crosslinking agent hexamethylenetetramine, and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the high-temperature gel system.

[0105] (4) High-temperature gel system: Dilute water glass with water (the volume ratio of water glass to water is 1:1), add carbonamide, the amount of carbonamide is 2wt% of the mass of water glass; weigh the above components according to the proportion and mix them, stir evenly to obtain the high-temperature gel system.

[0106] Example 2

[0107] The water-blocking system provided in this embodiment is as follows:

[0108] (1) Dilution-resistant gel system: The total mass of the dilution-resistant gel system is 100%. The dilution-resistant gel system includes 0.8 wt% of the first anionic polyacrylamide, 0.6 wt% of the first polyurethane, 0.4 wt% of hydroxypropyl methylcellulose, 0.4 wt% of the first phenolic crosslinking agent hydroquinone, 0.4 wt% of the first aldehyde crosslinking agent hexamethylenetetramine, and the balance water. The above components are weighed according to the proportions and mixed and stirred evenly to obtain the dilution-resistant gel plug.

[0109] (2) Weighted gel system: The total mass of the weighted gel system is 100%. The weighted gel system includes 0.8 wt% second anionic polyacrylamide, 0.8 wt% hydroxypropyl starch, 0.4 wt% phenolic crosslinking agent, 12 wt% potassium chloride as weighting agent, and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the weighted gel system.

[0110] (3) High-temperature gel system: The total mass of the high-temperature gel system is 100%. The high-temperature gel system includes 0.8 wt% of third anionic polyacrylamide, 0.6 wt% of second polyurethane, 0.4 wt% of second phenolic crosslinking agent hydroquinone, 0.4 wt% of second aldehyde crosslinking agent hexamethylenetetramine, and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the high-temperature gel system.

[0111] (4) High-temperature gel system: Dilute water glass with water (the volume ratio of water glass to water is 1:1.5), add carbonamide, the amount of carbonamide is 3wt% of the mass of water glass; weigh the above components according to the proportion and mix them, stir evenly to obtain the high-temperature gel system.

[0112] Example 3

[0113] The water-blocking system provided in this embodiment is as follows:

[0114] (1) Dilution-resistant gel system: The total mass of the dilution-resistant gel system is 100%. The dilution-resistant gel system includes 1.0 wt% of the first anionic polyacrylamide, 1.0 wt% of the first polyurethane, 0.6 wt% of hydroxypropyl methylcellulose, 0.6 wt% of the first phenolic crosslinking agent hydroquinone, 0.6 wt% of the first aldehyde crosslinking agent hexamethylenetetramine, and the balance water. The above components are weighed according to the proportions and mixed and stirred evenly to obtain the dilution-resistant gel plug.

[0115] (2) Weighted gel system: The total mass of the weighted gel system is 100%. The weighted gel system includes 1.0 wt% second anionic polyacrylamide, 1.0 wt% hydroxypropyl starch, 0.6 wt% phenolic crosslinking agent, 15 wt% potassium chloride as weighting agent and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the weighted gel system.

[0116] (3) High-temperature gel system: The total mass of the high-temperature gel system is 100%. The high-temperature gel system includes 1.0 wt% of third anionic polyacrylamide, 1.0 wt% of second polyurethane, 0.6 wt% of second phenolic crosslinking agent hydroquinone, 0.6 wt% of second aldehyde crosslinking agent hexamethylenetetramine, and the balance water. Weigh the above components according to the proportions, mix them, and stir evenly to obtain the high-temperature gel system.

[0117] (4) High-temperature gel system: Dilute water glass with water (the volume ratio of water glass to water is 1:2), add carbonamide, the amount of carbonamide is 4wt% of the mass of water glass; weigh the above components according to the proportion and mix them, stir evenly to obtain the high-temperature gel system.

[0118] Test Example 1 - Performance Evaluation of Water-Blocking System

[0119] At room temperature, using a mineralization of 20 × 104 The simulated formation water at a concentration of mg / L was used to weigh the raw materials according to the proportions of each component recorded in Examples 1 to 3. The raw materials were then completely dissolved in the simulated formation water to obtain dilution-resistant gel-1, weighted gel-1, high-temperature gel-1, high-temperature gel-1, dilution-resistant gel-2, weighted gel-2, high-temperature gel-2, high-temperature gel-2, dilution-resistant gel-3, weighted gel-3, high-temperature gel-3, and high-temperature gel-3 for testing.

[0120] A. Determination of gelation time and gel strength: Weigh 30g each of the dilution-resistant gel, weighted gel, high-temperature gel and high-temperature gel prepared in this test example, and place them in a constant temperature chamber set at 130℃ for aging. During the aging process, observe the gelation status of each gel and gel, and measure the gelation time and gel strength of each gel and gel according to the Sydansk visual code method. The results are shown in Table 1.

[0121] B. Density determination: The densities of the dilution-resistant gel, weighted gel, high-temperature gel, and high-temperature gel prepared in this test example were determined using a digital liquid density meter. The results are shown in Table 1.

[0122] C. High-temperature stability test: Weigh 30g each of the dilution-resistant gel, weighted gel, high-temperature gel, and high-temperature gel prepared in this test example and place them in separate containers. Seal the containers and start aging in a constant temperature chamber set at 130℃. After gel formation, continue aging at 130℃ and observe the dehydration after gel formation. Observe the amount of dehydration by visual inspection and divide the amount of dehydration by the volume after gel formation to obtain the dehydration rate. Here, the number of aging days when the dehydration rate reaches 10% is taken as the duration of high-temperature stability. The results are shown in Table 1.

[0123] Table 1. Performance testing of the water-blocking system

[0124]

[0125] As shown in Table 1, the water-blocking system provided by this invention has a suitable gelation time, sufficient gelation strength and suitable density at 130℃, and good high-temperature stability, making it suitable for sealing high-angle fractures in fractured-vuggy reservoirs.

[0126] Implementing methods for suppressing water sources and plugging deep high-angle cracks

[0127] During the development of fractured-vuggy reservoirs, 152 out of 296 wells exhibited high water cuts of 70% to 98%, representing 51.35% of the total. The water-blocking system and deep water-source suppression method for high-angle fractures provided in this invention were applied to manage these high-water-cut wells. The formation fractures in wells TPX1, TPX2, and TPX3 have angles of 50°, 60°, and 65° with the well axis, respectively, classifying them as high-angle fractures. A detailed explanation will be provided below using wells TPX1, TPX2, and TPX3 as examples.

[0128] Example 4

[0129] Using the water shut-off system provided in Example 1, the high-angle fracture deep water source suppression and shut-off method of this invention was implemented on the TPX1 well, and the reverse injection method with the tubing string stationary was used for construction. Specifically:

[0130] 1) The dilution-resistant gel system provided in Example 1 is used as a pre-slug and injected underground, where it adheres to the path of the subsequent slugs and acts as a plugging agent.

[0131] 2) Using the weighted gel system provided in Example 1 as an intermediate plug, it was injected underground to seal deep bottom water and suppress the intensity of strong bottom water;

[0132] 3) Inject the high-temperature gel system provided in Example 1 as a post-slug for near-wellbore plugging to expand the plugging range;

[0133] 4) Inject the high-temperature gel system provided in Example 1 as a sealing slug to prevent the front slug, intermediate slug and rear slug from backflowing and clogging the wellbore;

[0134] 5) Injecting oilfield water as a replacement slug further enhances the water-blocking effect of the aforementioned slug, while also preventing blockage in the wellbore. After the well is shut off, it will start flowing production.

[0135] During construction, the injection rate of each slug was 18m. 3 / h, the cumulative water injection volume of each section of the plug and the oilfield is 300m³. 3 Of which: the pre-slug injection volume accounted for 4%, with a cumulative injection volume of 12m³. 3 The intermediate segment of the plug accounted for 25% of the total injection volume, with a cumulative injection volume of 75m³. 3 The post-slug injection volume accounts for 30%, with a cumulative injection volume of 90m³. 3 The sealing slug injection volume accounts for 10%, with a cumulative injection volume of 30m³. 3 The cumulative water injection volume in the oilfield is 93m³. 3 .

[0136] Figure 1This example demonstrates the treatment of well TPX1. As can be seen, after treatment, well TPX1's daily fluid production increased to 34.8t, daily oil production increased from 3.1t before treatment to 13.5t after treatment, and water cut increased to 61.3%. The well has been producing continuously for 190 days, with a cumulative increase in oil production of 1419.3t, and is still increasing oil production.

[0137] Example 5

[0138] Using the water shut-off system provided in Example 2, the high-angle fracture deep water source suppression and shut-off method of this invention was implemented on the TPX2 well, and the reverse injection method with the tubing string stationary was used for construction. Specifically:

[0139] 1) The dilution-resistant gel system provided in Example 2 is used as a pre-slug and injected underground, where it adheres to the path of the subsequent slugs and acts as a plugging agent.

[0140] 2) Using the weighted gel system provided in Example 2 as an intermediate plug, it was injected underground to seal deep bottom water and suppress the intensity of strong bottom water;

[0141] 3) Inject the high-temperature gel system provided in Example 2 as a post-slug for near-wellbore sealing to expand the sealing range;

[0142] 4) Inject the high-temperature gel system provided in Example 2 as a sealing plug to prevent the front plug, intermediate plug and rear plug from backflowing and clogging the wellbore;

[0143] 5) Injecting oilfield water as a replacement slug further enhances the water-blocking effect of the aforementioned slug, while also preventing blockage in the wellbore. After the well is shut off, it will start flowing production.

[0144] During construction, the injection rate of each slug was 24m. 3 / h, a total of 400m³ of water was injected into each section of the plug and the oilfield. 3 Of which: the pre-slug injection volume accounted for 6%, with a cumulative injection volume of 24m³. 3 The main slug injection volume accounted for 28%, with a cumulative injection volume of 112m³. 3 The post-slug injection volume accounted for 34%, with a cumulative injection volume of 136m³. 3 The sealing slug injection volume accounted for 14%, with a cumulative injection volume of 56m³. 3 The cumulative water injection volume in the oilfield is 72m³. 3 .

[0145] Figure 2This example demonstrates the treatment of the TPX2 well. As can be seen, after treatment, the TPX2 well's daily fluid production increased to 16.8 tons, and its daily oil production rose from 0.8 tons before treatment to 8.5 tons after treatment, with a water cut of 49.6%. The well has been producing continuously for 180 days, accumulating an additional 1489.6 tons of oil, and is still increasing its oil production.

[0146] Example 6

[0147] Using the water shut-off system provided in Example 3, the high-angle fracture deep water source suppression and shut-off method of this invention was implemented on the TPX3 well, and the reverse injection method with the tubing string stationary was used for construction. Specifically:

[0148] 1) The dilution-resistant gel system provided in Example 3 is used as a pre-slug and injected underground, where it adheres to the path of the subsequent slugs and acts as a plugging agent.

[0149] 2) Using the weighted gel system provided in Example 3 as an intermediate plug, it was injected underground to seal deep bottom water and suppress the intensity of strong bottom water;

[0150] 3) Inject the high-temperature gel system provided in Example 3 as a post-slug for near-wellbore plugging to expand the plugging range;

[0151] 4) Inject the high-temperature gel system provided in Example 3 as a sealing plug to prevent the front plug, intermediate plug and rear plug from backflowing and clogging the wellbore;

[0152] 5) Injecting oilfield water as a replacement slug further enhances the water-blocking effect of the aforementioned slug, while also preventing blockage in the wellbore. After the well is shut off, it will start flowing production.

[0153] During construction, the injection rate of each slug was 30m. 3 / h, a total of 500m³ of water was injected into each section of the plug and the oilfield. 3 Of which: the pre-slug injection volume accounted for 8%, with a cumulative injection volume of 40m³. 3 The main slug injection volume accounts for 30%, with a cumulative injection volume of 150m³. 3 The post-slug injection volume accounted for 36%, with a cumulative injection volume of 180m³. 3 The sealing slug injection volume accounted for 16%, with a cumulative injection volume of 80m³. 3 Oilfield water; cumulative injection volume is 50m³ 3 .

[0154] Figure 3This example demonstrates the treatment of well TPX3. As can be seen, after treatment, well TPX3's daily fluid production reached 11.8 tons, and its daily oil production increased from 0 tons before treatment to 11.1 tons after treatment, with a water cut of 6.1%. The well has been producing continuously for 200 days, accumulating an additional 583.6 tons of oil, and is still increasing its oil production.

[0155] While the present invention has been described with reference to specific embodiments, those skilled in the art will understand that various changes can be made without departing from the true spirit and scope of the invention. Furthermore, numerous modifications can be made to the subject, spirit, and scope of the invention to suit specific situations, materials, material compositions, and methods. All such modifications are included within the scope of the claims of the present invention.

Claims

1. A water plugging system, comprising a dilution-tolerant gel system, a weighted gel system, a high-temperature gel system and a high-temperature gel system; the dilution-tolerant gel system comprises a first anionic polyacrylamide, a first polyurethane, hydroxypropyl methyl cellulose, a first phenolic crosslinking agent and a first aldehyde crosslinking agent; the weighted gel system comprises a second anionic polyacrylamide, hydroxypropyl starch, a phenolic crosslinking agent and a weighting agent; the high-temperature gel system comprises a third anionic polyacrylamide, a second polyurethane, a second phenolic crosslinking agent and a second aldehyde crosslinking agent; the high-temperature gel system comprises water glass and carbamide; the first anionic polyacrylamide has a weight average molecular weight of 12 x 10 4 ; the second anionic polyacrylamide has a weight average molecular weight of 10 x 10 4 ; and the third anionic polyacrylamide has a weight average molecular weight of 15 x 10 4 ; the first phenolic crosslinking agent and the second phenolic crosslinking agent are hydroquinone; the first aldehyde crosslinking agent and the second aldehyde crosslinking agent are urotropine; the phenolic crosslinking agent is a product obtained by condensation of naphthol and formaldehyde.

2. The water control system of claim 1, wherein, The total mass of the dilution-tolerant gel system is taken as 100%, the dilution-tolerant gel system comprises 0.6 to 1 wt% of the first anionic polyacrylamide, 0.4 to 1 wt% of the first polyurethane, 0.2 to 0.6 wt% of the hydroxypropyl methyl cellulose, 0.2 to 0.6 wt% of the first phenolic crosslinking agent, 0.2 to 0.6 wt% of the first aldehyde crosslinking agent and the balance of water.

3. The water control system of claim 1, wherein, The total mass of the weighted gel system is taken as 100%, the weighted gel system comprises 0.6 to 1 wt% of the second anionic polyacrylamide, 0.6 to 1 wt% of the hydroxypropyl starch, 0.2 to 0.6 wt% of the phenolic crosslinking agent, 10 to 15 wt% of the weighting agent and the balance of water.

4. The water control system of claim 1, wherein, The total mass of the high-temperature gel system is taken as 100%, the high-temperature gel system comprises 0.6 to 1 wt% of the third anionic polyacrylamide, 0.4 to 1 wt% of the second polyurethane, 0.2 to 0.6 wt% of the second phenolic crosslinking agent, 0.2 to 0.6 wt% of the second aldehyde crosslinking agent and the balance of water; and / or The mass of the water glass is taken as 100%, the amount of the carbamide is 2 to 4 wt%.

5. The water control system of any one of claims 1 to 4, wherein, The weight average molecular weight of the first polyurethane and the weight average molecular weight of the second polyurethane are 5500; and / or The weighting agent is potassium chloride.

6. A high-angle fracture deep-source water shutoff method, characterized in that, The water plugging system in any one of claims 1 to 5 is used as a water plugging agent, and water plugging is carried out in the manner of a slug combination; 1) the dilution-tolerant gel system is used as a front slug, injected into the ground and attached to the way of the subsequent slug to play a supporting role; 2) the weighted gel system is used as a middle slug, injected into the ground, plugs deep bottom water and inhibits the strength of strong bottom water; 3) the high-temperature gel system is injected as a back slug, carries out near-well plugging and expands the plugging range; 4) the high-temperature gel system is injected as a sealing slug to prevent the front slug, the middle slug and the back slug from returning and plugging the wellbore.

7. The method of claim 6, wherein, The method further comprises step 5) injecting water as a displacement slug.

8. The method of claim 7, wherein, The total injection volume of the pre-pad pack, the middle pack, the post-pad pack, the sealing pack and the displacement pack is 100%, the injection volume of the pre-pad pack accounts for 4-8%, the injection volume of the middle pack accounts for 25-30%, the injection volume of the post-pad pack accounts for 30-36%, the injection volume of the sealing pack accounts for 10-16%, and the injection volume of the displacement pack accounts for 10-31%.

9. The use of the water shutoff system according to any one of claims 1 to 5 or the high-angle fracture deep-source water shutoff method according to any one of claims 6 to 8 in water shutoff in a fracture-vug reservoir.

Images