A loose sandstone heavy oil reservoir plugging remover and use method thereof

Abstract

The present invention relates to the field of oil and gas extraction technology, and more particularly to a loose sandstone heavy oil reservoir plugging remover and a method for using the same. The loose sandstone heavy oil reservoir plugging remover comprises an organic plugging remover and an inorganic plugging remover. The plugging remover exhibits excellent plugging removal performance, significantly reducing construction costs while increasing oil well productivity.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploitation, and in particular to a loose sandstone heavy oil reservoir plugging remover and a use method thereof. Background Art

[0002] During the development of unconsolidated sandstone heavy oil reservoirs, viscosity reduction and sand control technologies are commonly used to improve well development efficiency. Thermal viscosity reduction is the primary method, supplemented by extrusion and packing to enhance sand control strength and extend its effectiveness. After multiple rounds of huff-and-puff operations in heavy oil wells, heavy components such as asphaltene and colloids, mixed with mud and fine sand, accumulate near the wellbore and around the filter screens, reducing permeability in these areas and leading to a decline in well production. Cold production viscosity reduction or acid plugging removal are unsatisfactory. During production, low liquid production requires hauling operations. Upon dissection, the filter screens often reveal no formation sand plugging. Traditionally, the sand control string has been removed, repacked, and then viscosity reduction measures implemented to restore normal production. However, these measures are costly, require a long construction period, and impact oil production uptime. There is a need for a plugging remover to increase well production and reduce operating costs.

[0003] At present, the known method for unblocking oil layers is to take conventional acidizing measures, but conventional acidizing cannot solve the above problems at one time, and the unblocking efficiency and effect are poor. In addition, Gao Manglai has applied for a patent for "Use of single-molecule quaternary ammonium salt compounds as clay stabilizing, anti-swelling and unblocking injection agents", patent publication number: CN1556169A. Mainly aimed at unblocking formations, it can stabilize formation clay and minerals, prevent clay swelling, and improve the permeability of formations (especially low permeability oil reservoirs), thereby greatly improving the water well injection effect and the sand control and imbibition effect of oil wells. The composition, mechanism of action (anti-swelling), and structure of the agent of this invention are significantly different from the mechanism of action (viscosity reduction + dissolution) of the present invention. The scope of application of existing inventions is narrow. Existing inventions can only solve inorganic blockages caused by clay expansion. The present invention can solve inorganic blockages and sand screen blockages caused by clay (or particles) expansion, shedding, migration, accumulation, and scaling, and can also solve organic blockages caused by oil viscosity and inverse emulsification, such as asphalt colloid blockage.

[0004] Patent publication number: CN105419760B, discloses a multi-component synergistic type plugging remover, the mass ratio of which is: 80-120 parts of water, 5-10 parts of cleaning dissolving agent, 15-20 parts of dissolving agent, 0.5-1 part of ammonium bifluoride, 0.4-0.6 parts of ninar, 2.5-3 parts of dodecyltrimethylammonium chloride, 0.1-0.3 parts of ammonium persulfate, 2.5-3 parts of SA-3 corrosion inhibitor, 3-5 parts of iron ion stabilizer for acidification. This patent is significantly different from the patent application in terms of ingredients. The existing invention has a wide range of applications but has two defects. (1) The existing invention has a weak effect on reducing the viscosity of blockages caused by deep oil viscosity. (2) The existing invention has a strong corrosive effect on metals and is not suitable for unblocking sand screen blockages. The formula of the present invention has been optimized through several experiments and has high viscosity reduction efficiency in reducing blockage caused by thick oil in deep areas. It has also been specially treated in removing blockage of sand control screen pipes, with high blockage removal efficiency and low damage.

[0005] Patent publication number: CN103224775B discloses a low-carbon mixed organic acid for oil well plugging removal, its preparation method, and application. This low-carbon mixed organic acid is primarily composed of the following raw materials by weight: 4-6% fatty alcohol, 2.4-2.5% ethylene oxide, 4-6% alkylbenzenesulfonic acid, 34-36% aminosulfonic acid, 24-26% oxalic acid, 4-6% biuret, 8-12% furazolidone, 8-12% 3-benzofuranone, and 2.4-2.6% sodium nitrite. This patent differs significantly from the patent application in terms of composition. The existing invention has a narrow scope of application. Existing inventions can only remove oil layer blockages (generally organic blockages such as asphalt colloid blockages) caused by heavy oil steam stimulation and improve the steam stimulation and production effect. The present invention can not only remove inorganic formation blockages and sand screen blockages caused by clay (or fine particles) expansion, shedding, migration, accumulation, and scaling, but also remove organic blockages caused by oil viscosity and inverse emulsification, including asphalt colloid blockages.

[0006] Patent Publication No.: CN107325800A, discloses a method for removing and suppressing blockages in heavy oil production and the use of nitrogen-containing organic compounds as blockage removers and inhibitors in heavy oil production. The method comprises: contacting a blockage remover and inhibitor with a blockage, wherein the blockage remover and inhibitor contains a nitrogen-containing organic compound; the blockage suppression method in heavy oil production comprises: first mixing a blockage remover and inhibitor with thin oil, and then injecting the thin oil containing the blockage remover and inhibitor into the oil well to contact the heavy oil, wherein the blockage remover and inhibitor contains a nitrogen-containing organic compound. This patent is significantly different from the patent application in terms of composition. The scope of application of the existing invention is narrow. The existing invention can only remove asphaltene, colloid and paraffin blockages in the oil layer caused by the production process of heavy oil wells. The present invention can not only remove inorganic formation blockages and sand screen blockages caused by clay (or fine particles) swelling, shedding, migration, accumulation and scaling, but also remove organic blockages caused by oil viscosity and reverse emulsification, including asphalt colloid blockages.

[0007] Patent publication number: CN111019621B discloses a plugging remover and its preparation method, comprising the following raw materials: Bacillus potzsteinii biosurfactant fermentation broth and hydrophobic nanosilica; it may also include an emulsifier, anti-scaling agent, anti-swelling agent, and cosolvent. The preparation method of the plugging remover comprises the following steps: first, adding the biosurfactant fermentation broth, emulsifier, and cosolvent to a reaction vessel, heating, and stirring uniformly; second, adding the anti-scaling agent and anti-swelling agent to the above solution, stirring to dissolve; finally, further heating the resulting solution, adding hydrophobic inorganic nanoparticles to the reaction vessel, and stirring uniformly. The plugging remover has low oil-water interfacial tension and can effectively strip and emulsify residual oil and colloidal asphaltene deposits in low- and medium-permeability layers to form a low-viscosity emulsion, remove organic blockages, withstand high mineralization, and be completely degraded by microorganisms. It is environmentally friendly. This patent significantly differs from the patent application in terms of composition. Existing inventions have a narrow scope of application. The existing invention can only remove the blockage of residual oil and deposited colloid and asphaltene in the near-wellbore area of ​​the transfer well and the clay hydration expansion. The present invention can not only remove the inorganic formation blockage and sand control screen blockage caused by clay (or fine particles) expansion, shedding, migration, accumulation, and scaling, but also remove the organic blockage caused by oil viscosity and reverse emulsification.

[0008] Patent Publication No. CN102250602A discloses a composite acid declogging agent for oil wells. It is composed of the following materials in parts by weight: 50-90 hydrochloric acid, 20-50 hydrofluoric acid, 15-35 acetic acid, 15-35 nitric acid, 4-10 corrosion inhibitor, 2-8 penetrant, 5-10 inorganic salt, 12-25 oxidant, and 10-30 clay stabilizer. This patent differs significantly from the patent application in terms of composition. Existing inventions have a narrow scope of application. Based on the formulation, existing inventions can only remove inorganic blockages near the wellbore and clay hydration swelling. The present invention can remove inorganic formation blockages and sand screen blockages caused by clay (or particulate) swelling, shedding, migration, accumulation, and scaling, as well as organic blockages caused by oil viscosity and reverse emulsification. In particular, it has a unique and efficient high-molecular viscosity reduction effect for heavy oil, which is not achieved by existing inventions.

[0009] Patent Publication No. CN115124989A discloses a heavy oil viscosity reduction cold recovery method and its application. The active polymer viscosity reducer used contains a series of active groups, and the surfactant is prepared by reacting at least one selected from polyvinyl alcohol, sulfonate, and aromatic acid with a second alkaline solution. The monomers used to prepare the active polymer viscosity reducer include acrylamide, acrylic acid, N-vinyl pyrrolidone, and sodium styrene sulfonate; the molar ratio of acrylamide, acrylic acid, N-vinyl pyrrolidone, and sodium styrene sulfonate is 1:1:1:3. Clearly, this patent differs significantly from the present invention in terms of ingredients, preparation, and formulation. The existing invention has a narrow scope of application. While the existing invention can only reduce heavy oil viscosity, the present invention can resolve inorganic formation blockages and sand screen blockages caused by clay (or fine particles) swelling, shedding, migration, accumulation, and scaling, as well as organic blockages caused by oil viscosity and inverse emulsification, providing highly effective heavy oil viscosity reduction. Summary of the Invention

[0010] To address the existing problem of conventional acidizing failing to resolve both organic and inorganic blockages simultaneously, leading to high sand control costs, the present invention provides a plugging remover for loose sandstone heavy oil reservoirs and a method for its use. The plugging remover comprises an organic and an inorganic agent, exhibiting excellent blockage removal performance, significantly reducing construction costs while increasing oil well productivity.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] The first aspect of the present invention provides an organic plugging remover, which is composed of the following raw materials: a polymer surfactant, an organic solvent, water and dodecylphenol polyoxyethylene ether;

[0013] The structural formula of the polymer surfactant is shown in Formula I below:

[0014]

[0015] Furthermore, the raw material ratio of the organic blocking remover is: 5-10 parts by weight of high molecular surfactant, 3-8 parts by weight of dodecylphenol polyoxyethylene ether, and 30-50 parts by weight of water per 100 parts by weight of organic solvent.

[0016] Furthermore, the organic solvent is one or more of toluene, xylene, methylnaphthalene, and 200# solvent oil.

[0017] The second aspect of the present invention provides a method for preparing the organic blocking remover described in the first aspect, the method comprising the following steps:

[0018] Preparation of the polymer surfactant:

[0019] Mix 60-100 parts of xylene, 30-60 parts of octadecyl acrylate and 50-100 parts of polymerizable surfactant NE-10, stir and heat. When the reactants are completely dissolved, raise the temperature to 75-85°C under nitrogen protection, add azobisisobutyronitrile and carry out reflux polymerization. After the reaction is completed, remove the solvent to obtain the product.

[0020] The high molecular surfactant and dodecylphenol polyoxyethylene ether are added into the organic solvent in proportion, water is added while stirring, and then high-speed stirring is performed to obtain the product.

[0021] In a third aspect, the present invention provides a plugging remover for loose sandstone heavy oil reservoirs, which is composed of an inorganic plugging remover and the organic plugging remover described in the first aspect.

[0022] Furthermore, the organic blocking agent and the inorganic blocking agent are composed in a volume ratio of 1-5:1-2.

[0023] Furthermore, the inorganic blocking agent is composed of the following ingredients and their weight parts: 20-25 parts of hydrochloric acid, 5-15 parts of hydrofluoric acid, 1-10 parts of fluoroboric acid, 1-5 parts of hydroxyethylidene diphosphonic acid, 1-5 parts of diethylenetriamine penta (methylene phosphonic acid), 1-5 parts of polyaspartic acid, 3-5 parts of acidifying corrosion inhibitor, 1-3 parts of anti-emulsifier, and 30-70 parts of water.

[0024] Furthermore, the acidifying corrosion inhibitor is a quinoline quaternary ammonium salt type acidifying corrosion inhibitor.

[0025] Furthermore, the anti-emulsifier is polyoxyethylene polyoxypropylene stearyl alcohol ether.

[0026] In a fourth aspect, the present invention provides a method for using the above-mentioned loose sandstone heavy oil reservoir plugging remover: after determining the formation blockage situation, first inject the organic plugging remover, then inject the inorganic plugging remover after the well is shut down, inject displacement fluid, and shut in the well for reaction.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The organic plugging remover of the present invention has excellent dispersing and dissolving effects on colloids, asphaltenes, and waxes, quickly removing organic blockages near the wellbore, restoring permeability in the near-wellbore zone and improving the well's fluid production capacity. The organic plugging remover of the present invention effectively prevents wax, colloids, and asphaltenes from reaggregating, providing a certain degree of anti-wax and anti-blocking effect. Compared to oil-based plugging removers, the organic plugging remover of the present invention can be formulated into a 5% to 10% aqueous solution, and its dissolving and dispersing effects on colloids, asphaltenes, and waxes are almost identical to those of oil-based plugging removers. While maintaining the same total amount of plugging remover, the plugging remover of the present invention has a wider unblocking range and a larger unblocking radius, enabling the unblocking of deep-seated organic matter.

[0029] The inorganic plugging removal system of the present invention contains multi-stage ionized weak acids such as fluoroboric acid, hydroxyethylidene diphosphonic acid, and diethylenetriamine penta (methylene phosphonic acid). The acid-rock reaction speed is slow, and deep acidization and plugging removal in the reservoir can be achieved. The plugging removal radius is large, and the plugging removal effect is better than that of the existing acid solution system. Hydroxyethylidene diphosphonic acid, diethylenetriamine penta (methylene phosphonic acid), and polyaspartic acid react with the Ca in the formation after the acid-rock reaction. 2+ Mg 2+ 、Fe 2+ 、Fe 3+ The metal ions have strong chelating ability, which can effectively prevent these metal ions from forming secondary precipitation in the reservoir and avoid causing secondary damage to the reservoir.

[0030] The inorganic and organic plugging removers of the present invention are mixed in different proportions to form a uniform emulsion without precipitation or flocculent formation, demonstrating good compatibility. Simultaneous use of the two agents will not cause secondary damage to the reservoir, nor will it affect the performance of either agent.

[0031] After unblocking the loose sandstone heavy oil reservoir, the unblocking agent of the present invention can increase the oil well productivity by more than 30% and reduce the construction cost by 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The viscosity reduction curves of organic matter with different concentrations of organic plugging remover are shown below;

[0033] Figure 2 The blocking curves of inorganic substances with different concentrations of inorganic blocking agents are shown in Figure 2.

[0034] Figure 3 This is a diagram showing the morphology of the emulsion after the organic blocking agent and the inorganic blocking agent of the present invention are combined. DETAILED DESCRIPTION

[0035] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0036] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0037] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0038] Example 1: An organic blocking agent

[0039] (1) Preparation method of polymer surfactant

[0040] In a three-necked flask equipped with a condenser, a thermometer, and a stirrer, 60 parts of solvent xylene was added, followed by 30 parts of octadecyl acrylate and 50 parts of NE-10. Stirring was started, the stirring speed was controlled at 100 rpm, and the temperature was raised to 60°C. When the reactants were completely dissolved, the temperature was raised to 80°C under nitrogen protection. About 0.1 parts of azobisisobutyronitrile was weighed and added to the three-necked flask. The mixture was refluxed and polymerized at 80°C for 8 hours. The solvent was evaporated using a rotary evaporator to obtain a polymer surfactant.

[0041] The structural formula of polymer surfactant is as follows:

[0042]

[0043] (2) Preparation method of organic blocking agent

[0044] Add 5 parts of the above-synthesized polymer surfactant and 8 parts of OP-10 to 100 parts of toluene, start stirring and control the speed to 500 rpm, add 30 parts of water while stirring, and stir at high speed for 1 hour to obtain an organic blocking agent.

[0045] Example 2: An organic blocking agent

[0046] (1) Preparation method of polymer surfactant

[0047] In a three-necked flask equipped with a condenser, a thermometer, and a stirrer, 100 parts of solvent xylene, 60 parts of octadecyl acrylate, and 100 parts of NE-10 were added, stirring was started, the stirring speed was controlled at 100 rpm, and the temperature was raised to 60°C. When the reactants were completely dissolved, the temperature was raised to 80°C under nitrogen protection. About 0.1 parts of azobisisobutyronitrile was weighed and added to the three-necked flask. Reflux polymerization was carried out at 80°C for 8 hours. The solvent was evaporated using a rotary evaporator to obtain a polymer surfactant.

[0048] (2) Preparation method of organic blocking agent

[0049] Add 10 parts of the above-synthesized polymer surfactant and 3 parts of OP-10 to 100 parts of an organic solvent (a mixture of toluene, xylene, methylnaphthalene, and 200# solvent oil), start stirring and control the speed to 500 rpm, add 50 parts of tap water while stirring, and stir at high speed for 1 hour to obtain an organic blocking agent.

[0050] Example 3: An organic blocking agent

[0051] (1) Preparation method of polymer surfactant

[0052] In a three-necked flask equipped with a condenser, a thermometer, and a stirrer, 80 parts of solvent xylene was added, followed by 50 parts of octadecyl acrylate and 80 parts of NE-10. Stirring was started, the stirring speed was controlled at 100 rpm, and the temperature was raised to 60°C. When the reactants were completely dissolved, the temperature was raised to 80°C under nitrogen protection. About 0.1 parts of azobisisobutyronitrile was weighed and added to the three-necked flask. The mixture was refluxed and polymerized at 80°C for 8 hours. The solvent was evaporated using a rotary evaporator to obtain a polymer surfactant.

[0053] (2) Preparation method of organic blocking agent

[0054] Add 7 parts of the above-synthesized polymer surfactant and 5 parts of OP-10 to 100 parts of the organic solvent xylene, start stirring and control the speed to 500 rpm, add 40 parts of water while stirring, and stir at high speed for 1 hour to obtain an organic blocking agent.

[0055] Example 4: A plugging remover for loose sandstone heavy oil reservoirs

[0056] The blocking agent is composed of an inorganic blocking agent and the organic blocking agent described in Example 1 in a volume ratio of 1:1.

[0057] The inorganic blocking agent is composed of the following components and their weight parts: 20 parts of hydrochloric acid, 5 parts of hydrofluoric acid, 1 part of fluoroboric acid, 1 part of hydroxyethylidene diphosphoric acid, 1 part of diethylenetriamine penta (methylene phosphonic acid), 1 part of polyaspartic acid, 3 parts of acidifying corrosion inhibitor, 1 part of anti-emulsifier, and 67 parts of water.

[0058] The acidifying corrosion inhibitor is a quinoline quaternary ammonium salt type acidifying corrosion inhibitor.

[0059] The anti-emulsifier is polyoxyethylene polyoxypropylene octadecyl alcohol ether.

[0060] Example 5: A plugging remover for loose sandstone heavy oil reservoirs

[0061] The blocking agent is composed of an inorganic blocking agent and the organic blocking agent described in Example 2 in a volume ratio of 1:2.

[0062] The inorganic blocking agent is composed of the following components and their weight parts: 22.5 parts of hydrochloric acid, 9.6 parts of hydrofluoric acid, 5.2 parts of fluoroboric acid, 2.9 parts of hydroxyethylidene diphosphonic acid, 2.5 parts of diethylenetriamine penta (methylene phosphonic acid), 2.3 parts of polyaspartic acid, 4.1 parts of acidifying corrosion inhibitor, 1.9 parts of anti-emulsifier, and 49 parts of water.

[0063] The acidifying corrosion inhibitor is a quinoline quaternary ammonium salt type acidifying corrosion inhibitor.

[0064] The anti-emulsifier is polyoxyethylene polyoxypropylene octadecyl alcohol ether.

[0065] Example 6: A plugging remover for loose sandstone heavy oil reservoirs

[0066] The blocking agent is composed of an inorganic blocking agent and the organic blocking agent described in Example 3 in a volume ratio of 2:1.

[0067] The inorganic blocking agent is composed of the following components and their weight parts: 25 parts of hydrochloric acid, 15 parts of hydrofluoric acid, 10 parts of fluoroboric acid, 5 parts of hydroxyethylidene diphosphoric acid, 5 parts of diethylenetriamine penta (methylene phosphonic acid), 5 parts of polyaspartic acid, 5 parts of acidifying corrosion inhibitor, 3 parts of anti-emulsifier, and 30 parts of water.

[0068] The acidifying corrosion inhibitor is a quinoline quaternary ammonium salt type acidifying corrosion inhibitor.

[0069] The anti-emulsifier is polyoxyethylene polyoxypropylene octadecyl alcohol ether.

[0070] Test example

[0071] The organic plugging remover in Example 3 was prepared into aqueous solutions of different concentrations, and its viscosity reduction rate on heavy oil was evaluated according to the method specified in Q / SH CG 0065-20216.6.3. The results are shown in the attached figure. Figure 1 It can be seen that with the increase of organic plugging remover concentration, the viscosity reduction rate gradually increases. The viscosity reduction rate of 10% organic plugging remover can reach more than 95%, and the viscosity reduction efficiency is high.

[0072] The plugging remover for sandstone heavy oil reservoirs in Example 6 was prepared into aqueous solutions of different concentrations to test its plugging removal rate on sandstone cores. The results are shown in the attached figure. Figure 2 As shown. Figure 2 It can be seen that the blocking rate of sandstone cores with 40% organic blocking agent can reach more than 80%, and the blocking effect is good.

[0073] Compatibility evaluation of inorganic and organic plugging removers

[0074] Mix the inorganic and organic plugging removers in different proportions to form a uniform emulsion with no precipitation or flocculent formation. The two have good compatibility. Figure 3 shown.

[0075] Subsequently, the wax dissolution rate, colloidal asphaltene dissolution rate, sandstone dissolution rate, corrosion rate and other indicators after mixing the organic and inorganic plugging removers in different proportions in Example 5 were investigated. The results are shown in Table 1 below.

[0076] Table 1 Effects of mixing organic and inorganic plugging removers in different proportions

[0077]

[0078] The experimental data above show that mixing organic and inorganic plugging removers in different proportions has no significant effect on the organic remover's wax dissolution rate or the colloidal asphaltene dissolution rate. It also has no effect on the inorganic remover's sandstone core dissolution rate or corrosion rate. This indicates that using both removers simultaneously will not cause secondary damage to the reservoir, nor will it affect their performance.

[0079] On-site construction methods

[0080] Construction wellhead requirements: The pressure resistance value complies with relevant technical standards.

[0081] Construction vehicle requirements: 1 700-type pump truck, 12m 3 1 fiberglass pool, 2 residual liquid recovery tank trucks, and 2 water tank trucks.

[0082] The construction procedure is as follows, and the following are necessary steps.

[0083] (1) The construction personnel shall stop the pumping unit at the top dead center, brake the pumping unit, and tighten the wellhead top screw and the first and second level packings.

[0084] (2) Connect the backwash well pipeline. After the surface pipeline passes the pressure test, use the produced water from the oil field in this block to backwash the well for more than two weeks.

[0085] (3) According to the operating procedures, the pumping unit is pressurized. When the pressure rises to 3.0 MPa, the well is stopped and the pressure is stabilized for 5 minutes. If the pressure drop is no more than 0.2 MPa, it is qualified. If it is unqualified, the pump unblocking construction is stopped and a new plan is determined.

[0086] (4) Turn the polishing rod upside down, close the main gate of the wellhead, tighten the wellhead top screw, and fix the wellhead to the ground anchor with four tension ropes.

[0087] (5) Close the high-pressure gate at the process outlet, and try to squeeze the oilfield produced water through the casing. After the pressure stabilizes, continue squeezing for 20m 3 , measure the water absorption capacity and pressure drop, and determine the formation blockage situation.

[0088] (6) Back-extrusion of the organic plugging remover described in Example 4, and the well was kept for 3 days.

[0089] (7) Back-extrusion of the inorganic plugging remover described in Example 4.

[0090] (8) Backsqueeze displacement fluid (oilfield produced water).

[0091] (9) After shutting in the well for 1 hour, release the pressure on the oil and casing respectively, install the polished rod and blowout preventer, and then pull the liquid out for production. Use pH test paper to test. If the pH value reaches 6-7, it is qualified and handed over to the oil production management unit for dry production.

[0092] The implementation results of each well are shown in Table 2 below.

[0093] Table 2 Statistics of the effects of on-site implementation of plugging relief measures

[0094]

[0095] The comparison of construction cost accounting is shown in Table 3 below.

[0096] Table 3 Construction cost accounting table*

[0097]

[0098] *Note: Based on the oil layer thickness of 12.0m, porosity of 39.0%, and permeability of 920×10 -3 um 2 , the designed treatment radius is 5.8m.

[0099] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An organic blocking agent, characterized in that: It is composed of the following raw materials: High molecular surfactant, organic solvent, water and dodecylphenol polyoxyethylene ether; Preparation of the polymer surfactant: Mix 60-100 parts of xylene, 30-60 parts of octadecyl acrylate and 50-100 parts of polymerizable surfactant NE-10, stir and heat. When the reactants are completely dissolved, raise the temperature to 75-85°C under nitrogen protection, add azobisisobutyronitrile and carry out reflux polymerization. After the reaction is completed, remove the solvent to obtain a high molecular surfactant. The proportion of the raw materials is as follows: 5-10 parts by weight of the high molecular surfactant, 3-8 parts by weight of dodecylphenol polyoxyethylene ether and 30-50 parts by weight of water per 100 parts by weight of the organic solvent.

2. The organic blocking agent according to claim 1, characterized in that The organic solvent is one or more of toluene, xylene, methylnaphthalene, and 200# solvent oil.

3. The method for preparing the organic blocking agent according to any one of claims 1 to 2, characterized in that: The following steps are involved: The high molecular surfactant and dodecylphenol polyoxyethylene ether are added into the organic solvent in proportion, water is added while stirring, and then high-speed stirring is performed to obtain the product.

4. A plugging remover for loose sandstone heavy oil reservoirs, characterized in that: It consists of an inorganic blocking agent and the organic blocking agent according to any one of claims 1 to 3; The inorganic blocking agent is composed of the following components and their weight parts: 20-25 parts of hydrochloric acid, 5-15 parts of hydrofluoric acid, 1-10 parts of fluoroboric acid, 1-5 parts of hydroxyethylidene diphosphoric acid, 1-5 parts of diethylenetriamine penta (methylene phosphonic acid), 1-5 parts of polyaspartic acid, 3-5 parts of acidifying corrosion inhibitor, 1-3 parts of anti-emulsifier, and 30-70 parts of water.

5. The loose sandstone heavy oil reservoir plugging remover according to claim 4, characterized in that: The organic blocking agent and the inorganic blocking agent are composed of a volume ratio of 1-5:1-2.

6. The loose sandstone heavy oil reservoir plugging remover according to claim 4, characterized in that: The acidifying corrosion inhibitor is a quinoline quaternary ammonium salt type acidifying corrosion inhibitor.

7. The plugging remover for loose sandstone heavy oil reservoirs according to claim 4, characterized in that: The anti-emulsifier is polyoxyethylene polyoxypropylene octadecyl alcohol ether.

8. The method for using the plugging remover for loose sandstone heavy oil reservoirs according to any one of claims 4 to 7, characterized in that: After determining the blockage situation of the formation, the organic blocking agent is injected first, and then the inorganic blocking agent is injected after the well is soaked, and the displacement fluid is injected, and the well is shut in for reaction.

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