Selective blocking remover for heavy oil reservoir horizontal well and construction method

Abstract

The invention belongs to the technical field of methods for improving recovery efficiency in oilfield development, and discloses a selective blocking remover for a heavy oil reservoir horizontal well and a construction method. The selective blocking remover comprises a shielding temporary blocking agent and an acidification blocking remover; the shielding temporary plugging agent and the acidification plugging removal agent are used in a combined mode in specific use. The shielding temporary plugging agent can shield and temporarily plug large pore channels or high-permeability zones of reservoirs, and the acidification plugging removal agent can perform acidification treatment on low-permeability reservoirs, so that the purpose of targeted plugging removal is achieved, and the development effect of heavy oil reservoir horizontal wells can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of methods for improving oil field recovery, and relates to a selective plugging remover for horizontal wells in heavy oil reservoirs and a construction method. Background Art

[0002] During the production process of heavy oil horizontal wells, the permeability of oil wells is greatly reduced due to the invasion of foreign liquids or solids, such as the loss of drilling fluids, the damage caused by the incompatibility of well repairing fluids and well washing fluids, and the injection of various chemical production-increasing agents, which leads to a significant decrease in the oil well production and even shutdown, seriously affecting the normal development of the oil field and the improvement of the final recovery rate of crude oil. In order to remove the blockage of oil layers near the well and improve the production capacity of oil wells, physical and chemical and other composite oil layer plugging removal measures have been developed at home and abroad. Among them, the oil layer chemical acid plugging removal method has become the most commonly used and effective plugging and production increase measure in recent years due to its simple on-site construction, convenience, fast, practical and efficient, and low cost. However, the horizontal wells in heavy oil reservoirs are long, the vertical permeability of the oil layers varies greatly, the small layers in some wells are not obviously developed, and the oil wells are limited by the casing deformation. The conditions for tool sealing are not met. Conventional general oil layer plugging removal processes are difficult to act on the low permeability part of the reservoir, and the low permeability reservoir is exactly the part that needs to be transformed. In view of the above problems, it is urgent to develop a selective plugging remover for horizontal wells in heavy oil reservoirs and a specific use method to overcome the above problems. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, the present invention provides a selective unblocking agent and a construction method for horizontal wells in heavy oil reservoirs. The selective unblocking agent includes a shielding temporary plugging agent and an acidizing unblocking agent; the shielding temporary plugging agent can shield and temporarily plug large pores or high permeability zones of the reservoir, and the acidizing unblocking agent can perform acidizing treatment on low permeability reservoirs to achieve the purpose of targeted unblocking, which can effectively improve the development effect of horizontal wells in heavy oil reservoirs.

[0004] The above object of the present invention is achieved through the following technical solutions:

[0005] A selective plugging remover for horizontal wells in heavy oil reservoirs, comprising a shielding temporary plugging agent and an acidizing plugging remover; the shielding temporary plugging agent and the acidizing plugging remover are used in combination when used.

[0006] The acidizing and plugging-removing agent is designed according to the specific production conditions of different heavy oil wells, and the content of each component is as follows by weight percentage: 5-15% HCl, 1-2% hydrofluoric acid, 0.3-0.8% sorbitan tristearate, 0.04-0.08% sorbitan oleate polyoxyethylene ether, 0.05-0.1% ethylene glycol tert-butyl ether, 0.3-0.5% imidazoline corrosion inhibitor, 0.02-0.04% drainage aid, 0.4-0.8% clay stabilizer, 0.2-0.5% iron ion stabilizer, 0.6-0.8% anti-acid slag agent, and the balance is water.

[0007] Furthermore, the preparation method of the above-mentioned acidified plugging remover is: first, HCl, polycarboxylic acid, hydrofluoric acid, iron ion stabilizer, corrosion inhibitor, clay stabilizer, and anti-acid slag agent are added to water in sequence, and after the drainage agent is stirred evenly, sorbitan tristearate, sorbitan tristearate, and ethylene glycol tert-butyl ether are added to obtain the acidified plugging remover.

[0008] Furthermore, the imidazoline corrosion inhibitor in the acid plugging remover is preferably imidazoline quaternary ammonium salt; the drainage aid is preferably modified alkyl polyglycoside; the clay stabilizer is preferably chlorine-free clay stabilizer NW-1; the iron ion stabilizer is preferably aminocarboxylic complexing agent; and the acid-resistant slag agent is preferably modified sulfide. Modified alkyl polyglycoside is commercially available, preferably model F3237. Modified sulfide is commercially available, preferably model SS-K1.

[0009] The shielding temporary plugging agent is designed with the concentration of each component according to the specific production conditions of different heavy oil wells. The content of each component is as follows by weight percentage: 10-20% limestone, 10-25% fly ash, 5-15% silicon dioxide, 0.2-0.8% modifier, 0.4-1% toughening agent, 0.8-2% activator, and the balance is water.

[0010] The construction method of the selective plugging remover for horizontal wells in heavy oil reservoirs is as follows:

[0011] (1) The injection of plugs is specifically as follows: the injection of selective plugging agent consists of three plugs; the first plug injects acid plugging agent to perform preliminary plugging treatment on the oil layer; the second plug injects shielding temporary plugging agent to block the high permeability pores; the third plug injects acid plugging agent again to perform plugging treatment on the low permeability oil layer.

[0012] (2) The specific injection volume is: the radius of the blockage removal is determined according to the degree of blockage, and the specific injection volume of each blockage is Q = πR 2 hΦ is calculated; where Q is the injection volume, in m 3 ; π is the ratio of pi, which is 3.14; R is the treatment radius, in m; h is the oil layer thickness, in m; Φ is the oil layer porosity, in %.

[0013] Furthermore, the injection volume is divided into three cases according to the degree of blockage, as follows:

[0014] (a) When the blockage is relatively light, the first section plug treatment radius is designed to be 1-1.5m, the second section plug radius is designed to be 0.3-0.6m, and the third section plug treatment radius is designed to be 1-1.5m.

[0015] (b) When the blockage degree is moderate, the first section plug treatment radius is designed to be 1.5-2.5m, the second section plug radius is designed to be 0.6-0.9m, and the third section plug treatment radius is designed to be 1.5-2.5m.

[0016] (c) When the blockage degree is serious, the first section plug treatment radius is designed to be 2.5-4m, the second section plug radius is designed to be 0.9-1.5m, and the third section plug treatment radius is designed to be 2.5-4m.

[0017] Furthermore, the construction method adopts a large-volume injection method, the construction pressure is controlled below 20MPa, and the injection speed is controlled at 15-20m 3 / h.

[0018] The present invention also claims protection for the use of the selective plugging remover in the plugging removal of horizontal wells in heavy oil reservoirs.

[0019] Another object of the present invention is to protect the application of the construction method of the above-mentioned selective plugging remover in the plugging removal of horizontal wells in heavy oil reservoirs.

[0020] The beneficial effects of the present invention compared with the prior art are:

[0021] The present invention provides a selective unblocking agent and a construction method for horizontal wells in heavy oil reservoirs. The selective unblocking agent comprises a shielding temporary plugging agent and an acidizing unblocking agent. The shielding temporary plugging agent can shield and temporarily plug large pores or high permeability zones of the reservoir, and the acidizing unblocking agent can perform acidizing treatment on low permeability reservoirs to achieve the purpose of targeted unblocking, which can effectively improve the development effect of horizontal wells in heavy oil reservoirs.

[0022] The invention provides a selective plugging remover for horizontal wells in heavy oil reservoirs and a construction method thereof. The selective plugging remover comprises a shielding temporary plugging agent and an acidizing plugging remover. The new shielding temporary plugging agent with high strength shields and temporarily plugs large pores or high permeability zones of the reservoir, and the acidizing plugging remover is used in conjunction with the acidizing plugging remover to force the acidizing plugging remover injected later to turn to the low permeability zone, so as to achieve the oil layer treatment and transformation of the low permeability damaged layer. Meanwhile, the shielding temporary plugging agent can be automatically released during the production process, so as to achieve the purpose of temporarily plugging the high permeability layer and unblocking the low permeability layer.

[0023] The selective plugging remover and construction method for horizontal wells in heavy oil reservoirs provided by the present invention can effectively treat and transform the low permeability damaged layer after being applied in the horizontal wells in heavy oil reservoirs, achieving the purpose of temporarily plugging the high permeability layer and unblocking the low permeability layer. After implementation, the steam injection pressure dropped by 2Mpa, and the periodic oil production increased from 99.7t to 1411.7t, increasing oil production by 1312t, achieving a significant oil increase effect. DETAILED DESCRIPTION

[0024] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0025] Example 1

[0026] A selective plugging remover for horizontal wells in heavy oil reservoirs, comprising a shielding temporary plugging agent and an acidizing plugging remover; the shielding temporary plugging agent and the acidizing plugging remover are used in combination when used.

[0027] The acidizing and plugging-removing agent is designed according to the specific production conditions of different heavy oil wells, and the content of each component is as follows by weight percentage: 10% HCl, 1% hydrofluoric acid, 0.4% sorbitan tristearate, 0.05% sorbitan oleate polyoxyethylene ether, 0.05% ethylene glycol tert-butyl ether, 0.4% imidazoline corrosion inhibitor, 0.02% drainage aid, 0.5% clay stabilizer, 0.3% iron ion stabilizer, 0.6% anti-acid slag agent, and the balance is water.

[0028] The preparation method of the above-mentioned acidified plugging remover is as follows: first, HCl, polycarboxylic acid, hydrofluoric acid, iron ion stabilizer, corrosion inhibitor, clay stabilizer, and anti-acid slag agent are added to water in sequence, and after the drainage agent is stirred evenly, sorbitan tristearate, sorbitan tristearate, and ethylene glycol tert-butyl ether are added to obtain the acidified plugging remover.

[0029] The imidazoline corrosion inhibitor in the acid plugging remover is preferably imidazoline quaternary ammonium salt; the drainage aid is preferably modified alkyl glycoside; the clay stabilizer is preferably chloride-free clay stabilizer NW-1; the iron ion stabilizer is preferably aminocarboxylic acid complexing agent; and the anti-acid slag agent is preferably modified sulfide.

[0030] The shielding temporary plugging agent has the concentration of each component designed according to the specific production conditions of different heavy oil wells. The composition of each component is as follows by weight percentage: 14% limestone, 15% fly ash, 6% silica, 0.2% modifier, 0.4% toughening agent, 1% activator, and the balance is water.

[0031] The construction method of the selective plugging remover for horizontal wells in heavy oil reservoirs is as follows:

[0032] (1) The injection of plugs is specifically as follows: the injection of selective plugging agent consists of three plugs; the first plug injects acid plugging agent to perform preliminary plugging treatment on the oil layer; the second plug injects shielding temporary plugging agent to block the high permeability pores; the third plug injects acid plugging agent again to perform plugging treatment on the low permeability oil layer.

[0033] (2) The specific injection volume is: the radius of the blockage removal is determined according to the degree of blockage, and the specific injection volume of each blockage is Q = πR 2 hΦ is calculated; where Q is the injection volume, in m 3 ; π is the ratio of pi, which is 3.14; R is the treatment radius, in m; h is the oil layer thickness, in m; Φ is the oil layer porosity, in %.

[0034] The injection volume is divided into three cases according to the degree of blockage, as follows:

[0035] (a) When the blockage is relatively light, the first section plug treatment radius is designed to be 1-1.5m, the second section plug radius is designed to be 0.3-0.6m, and the third section plug treatment radius is designed to be 1-1.5m.

[0036] (b) When the blockage degree is moderate, the first section plug treatment radius is designed to be 1.5-2.5m, the second section plug radius is designed to be 0.6-0.9m, and the third section plug treatment radius is designed to be 1.5-2.5m.

[0037] (c) When the blockage degree is serious, the first section plug treatment radius is designed to be 2.5-4m, the second section plug radius is designed to be 0.9-1.5m, and the third section plug treatment radius is designed to be 2.5-4m.

[0038] The construction method adopts large-volume injection, the construction pressure is controlled below 20MPa, and the injection speed is controlled at 15-20m 3 / h.

[0039] Example 2

[0040] A selective plugging remover for horizontal wells in heavy oil reservoirs, comprising a shielding temporary plugging agent and an acidizing plugging remover; the shielding temporary plugging agent and the acidizing plugging remover are used in combination when used.

[0041] The acidizing and plugging-removing agent is designed according to the specific production conditions of different heavy oil wells, and the content of each component is as follows by weight percentage: 5% HCl, 1% hydrofluoric acid, 0.3% sorbitan tristearate, 0.04% sorbitan oleate polyoxyethylene ether, 0.05% ethylene glycol tert-butyl ether, 0.3% imidazoline corrosion inhibitor, 0.02% drainage aid, 0.4% clay stabilizer, 0.2% iron ion stabilizer, 0.6% anti-acid slag agent, and the balance is water.

[0042] The preparation method of the above-mentioned acidified plugging remover is as follows: first, HCl, polycarboxylic acid, hydrofluoric acid, iron ion stabilizer, corrosion inhibitor, clay stabilizer, and anti-acid slag agent are added to water in sequence, and after the drainage agent is stirred evenly, sorbitan tristearate, sorbitan tristearate, and ethylene glycol tert-butyl ether are added to obtain the acidified plugging remover.

[0043] The imidazoline corrosion inhibitor in the acid plugging remover is preferably imidazoline quaternary ammonium salt; the drainage aid is preferably modified alkyl glycoside; the clay stabilizer is preferably chloride-free clay stabilizer NW-1; the iron ion stabilizer is preferably aminocarboxylic acid complexing agent; and the anti-acid slag agent is preferably modified sulfide.

[0044] The shielding temporary plugging agent has the concentration of each component designed according to the specific production conditions of different heavy oil wells. The content of each component is as follows by weight percentage: 10% limestone, 10% fly ash, 5% silica, 0.2% modifier, 0.4% toughening agent, 0.8% activator, and the balance is water.

[0045] The construction method of the selective plugging remover for horizontal wells in heavy oil reservoirs is as follows:

[0046] (1) The injection of plugs is specifically as follows: the injection of selective plugging agent consists of three plugs; the first plug injects acid plugging agent to perform preliminary plugging treatment on the oil layer; the second plug injects shielding temporary plugging agent to block the high permeability pores; the third plug injects acid plugging agent again to perform plugging treatment on the low permeability oil layer.

[0047] (2) The specific injection volume is: the radius of the blockage removal is determined according to the degree of blockage, and the specific injection volume of each blockage is Q = πR 2 hΦ is calculated; where Q is the injection volume, in m 3 ; π is the ratio of pi, which is 3.14; R is the treatment radius, in m; h is the oil layer thickness, in m; Φ is the oil layer porosity, in %.

[0048] The injection volume is divided into three cases according to the degree of blockage, as follows:

[0049] (a) When the blockage is relatively light, the first section plug treatment radius is designed to be 1m, the second section plug radius is designed to be 0.3m, and the third section plug treatment radius is designed to be 1m.

[0050] (b) When the blockage degree is medium, the first section plug treatment radius is designed to be 1.5m, the second section plug radius is designed to be 0.6m, and the third section plug treatment radius is designed to be 1.5m.

[0051] (c) When the blockage degree is serious, the first section plug treatment radius is designed to be 2.5m, the second section plug radius is designed to be 0.9m, and the third section plug treatment radius is designed to be 2.5m.

[0052] The construction method adopts large-volume injection, the construction pressure is controlled below 20MPa, and the injection speed is controlled at 15-20m 3 / h.

[0053] Example 3

[0054] A selective plugging remover for horizontal wells in heavy oil reservoirs, comprising a shielding temporary plugging agent and an acidizing plugging remover; the shielding temporary plugging agent and the acidizing plugging remover are used in combination when used.

[0055] The acidizing and plugging-removing agent is designed according to the specific production conditions of different heavy oil wells, and the content of each component is as follows by weight percentage: 15% HCl, 2% hydrofluoric acid, 0.8% sorbitan tristearate, 0.08% sorbitan oleate polyoxyethylene ether, 0.1% ethylene glycol tert-butyl ether, 0.5% imidazoline corrosion inhibitor, 0.04% drainage aid, 0.8% clay stabilizer, 0.5% iron ion stabilizer, 0.8% anti-acid slag agent, and the balance is water.

[0056] The preparation method of the above-mentioned acidified plugging remover is as follows: first, HCl, polycarboxylic acid, hydrofluoric acid, iron ion stabilizer, corrosion inhibitor, clay stabilizer, and anti-acid slag agent are added to water in sequence, and after the drainage agent is stirred evenly, sorbitan tristearate, sorbitan tristearate, and ethylene glycol tert-butyl ether are added to obtain the acidified plugging remover.

[0057] The imidazoline corrosion inhibitor in the acid plugging remover is preferably imidazoline quaternary ammonium salt; the drainage aid is preferably modified alkyl glycoside; the clay stabilizer is preferably chloride-free clay stabilizer NW-1; the iron ion stabilizer is preferably aminocarboxylic acid complexing agent; and the anti-acid slag agent is preferably modified sulfide.

[0058] The shielding temporary plugging agent is designed with the concentration of each component according to the specific production conditions of different heavy oil wells. The content of each component is as follows by weight percentage: 20% limestone, 25% fly ash, 15% silica, 0.8% modifier, 1% toughening agent, 2% activator, and the balance is water.

[0059] The construction method of the selective plugging remover for horizontal wells in heavy oil reservoirs is as follows:

[0060] (1) The injection of plugs is specifically as follows: the injection of selective plugging agent consists of three plugs; the first plug injects acid plugging agent to perform preliminary plugging treatment on the oil layer; the second plug injects shielding temporary plugging agent to block the high permeability pores; the third plug injects acid plugging agent again to perform plugging treatment on the low permeability oil layer.

[0061] (2) The specific injection volume is: the radius of the blockage removal is determined according to the degree of blockage, and the specific injection volume of each blockage is Q = πR 2hΦ is calculated; where Q is the injection volume, in m 3 ; π is the ratio of pi, which is 3.14; R is the treatment radius, in m; h is the oil layer thickness, in m; Φ is the oil layer porosity, in %.

[0062] The injection volume is divided into three cases according to the degree of blockage, as follows:

[0063] (a) When the blockage is relatively light, the first section plug treatment radius is designed to be 1.5m, the second section plug radius is designed to be 0.6m, and the third section plug radius is designed to be 1.5m.

[0064] (b) When the blockage degree is medium, the first section plug treatment radius is designed to be 2.5m, the second section plug radius is designed to be 0.9m, and the third section plug treatment radius is designed to be 2.5m.

[0065] (c) When the blockage degree is serious, the first section plug treatment radius is designed to be 4m, the second section plug radius is designed to be 1.5m, and the third section plug treatment radius is designed to be 4m.

[0066] The construction method adopts large-volume injection, the construction pressure is controlled below 20MPa, and the injection speed is controlled at 15-20m 3 / h.

[0067] Application Example 1

[0068] The first embodiment of the present invention was applied in a horizontal well test in a heavy oil block of a certain oil field, and achieved good implementation results, which was specifically achieved as follows:

[0069] Well A-1 is a water well in the eastern part of the heavy oil block. It has been put into production for 3 cycles. The production time is short, the daily liquid production is only 5.8 tons, and the daily oil production is 0.6 tons, and the production effect is poor. Analysis shows that the main reason for the low liquid production capacity is the presence of a certain degree of mud pollution during drilling. The horizontal section of the well is long and the permeability difference is large. The selective plugging remover and construction method prepared in Implementation 1 are used for plugging removal.

[0070] The application method is as follows:

[0071] Step 1: Run the unblocking string with packer (existing technology), connect the wellhead pipeline in a positive squeeze mode after setting, test the pipeline pressure at 30MPa, and it is qualified if there is no puncture or leakage for 15 minutes. Open the oil pipe valve and positively displace 20m3 of sewage at room temperature. 3 As a pre-fluid, its purpose is to clean the wellbore and ensure smooth and safe injection during on-site construction;

[0072] Step 2: Inject 100t of acid plugging agent into the target layer in the first section, and control the displacement at 15-20m 3 / h, after the end, it will replace 20m2 of sewage at room temperature3 ;

[0073] Step 3: Continue to inject 40t of temporary blocking agent into the target layer, and control the displacement at 5-8m 3 / h, the construction pressure is controlled within 10MPa, and after completion, 20m2 of sewage at room temperature is displaced. 3 ;

[0074] Step 4: Continue to pump 100t of acid plugging agent into the target layer in the third section, and control the displacement at 15-20m 3 / h, after the end, it will replace 20m2 of sewage at room temperature 3 , construction completed.

[0075] Blockage-relieving effect:

[0076] After the application was implemented, the steam injection pressure dropped by 2Mpa, and the periodic oil production increased from 99.7t to 1411.7t, with an increase of 1312t, achieving a significant oil production increase effect.

[0077] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A selective plugging remover for horizontal wells in heavy oil reservoirs, characterized in that: The selective plugging remover includes a shielding temporary plugging agent and an acidizing plugging remover; the shielding temporary plugging agent and the acidizing plugging remover are used in combination when used.

2. A selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 1, characterized in that: The acidulant blockage remover comprises the following components in percentage by weight: 5-15% HCl, 1-2% hydrofluoric acid, 0.3-0.8% sorbitan tristearate, 0.04-0.08% sorbitan oleate polyoxyethylene ether, 0.05-0.1% ethylene glycol tert-butyl ether, 0.3-0.5% imidazoline corrosion inhibitor, 0.02-0.04% drainage aid, 0.4-0.8% clay stabilizer, 0.2-0.5% iron ion stabilizer, 0.6-0.8% anti-acid slag agent, and the balance is water.

3. A selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 2, characterized in that: The preparation method of the acid plugging remover is as follows: first, HCl, polycarboxylic acid, hydrofluoric acid, iron ion stabilizer, corrosion inhibitor, clay stabilizer, and anti-acid slag agent are sequentially added into water, and after the drainage aid is stirred evenly, sorbitan tristearate, sorbitan tristearate, and ethylene glycol tert-butyl ether are continuously added to obtain the acid plugging remover.

4. A selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 2, characterized in that The shielding temporary plugging agent comprises the following components in percentage by weight: 10-20% limestone, 10-25% fly ash, 5-15% silicon dioxide, 0.2-0.8% modifier, 0.4-1% toughening agent, 0.8-2% activator, and the balance is water.

5. A selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 4, characterized in that: The imidazoline corrosion inhibitor in the acidizing plugging remover is imidazoline quaternary ammonium salt; the drainage aid is modified alkyl polyglycoside; the clay stabilizer is chloride-free clay stabilizer NW-1; the iron ion stabilizer is aminocarboxylic complexing agent; and the acid-resistant slag agent is modified sulfide.

6. A construction method for a selective plugging remover for horizontal wells in heavy oil reservoirs according to any one of claims 1 to 5, characterized in that: (1) The injection of slugs is specifically as follows: the injection of selective plugging agent consists of three slugs; the first slug injects acid plugging agent to perform preliminary plugging treatment on the oil layer; the second slug injects shielding temporary plugging agent to block the high permeability pores; the third slug injects acid plugging agent again to perform plugging treatment on the low permeability oil layer; (2) The specific injection volume is: the radius of the blockage removal is determined according to the degree of blockage, and the specific injection volume of each blockage is Q = πR 2 hΦ is calculated; where Q is the injection volume, in m 3 ; π is the ratio of pi, which is 3.14; R is the treatment radius, in m; h is the oil layer thickness, in m; Φ is the oil layer porosity, in %.

7. A construction method for a selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 6, characterized in that: The injection volume is divided into three cases according to the degree of blockage, as follows: (a) When the blockage is relatively light, the first slug treatment radius is designed to be 1-1.5m, the second slug radius is designed to be 0.3-0.6m, and the third slug treatment radius is designed to be 1-1.5m; (b) When the blockage degree is medium, the first slug treatment radius is designed to be 1.5-2.5m, the second slug radius is designed to be 0.6-0.9m, and the third slug treatment radius is designed to be 1.5-2.5m; (c) When the blockage degree is serious, the first section plug treatment radius is designed to be 2.5-4m, the second section plug radius is designed to be 0.9-1.5m, and the third section plug treatment radius is designed to be 2.5-4m.

8. A construction method for a selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in claim 7, characterized in that: The construction method adopts large-volume injection, the construction pressure is controlled below 20MPa, and the injection speed is controlled at 15-20m 3 / h.

9. Use of the selective plugging remover for horizontal wells in heavy oil reservoirs as claimed in any one of claims 1 to 5 in unblocking horizontal wells in heavy oil reservoirs.

10. The construction method of the selective unblocking agent for horizontal wells in heavy oil reservoirs according to any one of claims 7 to 8 is used for unblocking horizontal wells in heavy oil reservoirs.