Paraffin removal viscosity reducer for hydraulic jet paraffin removal as well as preparation method and use method of paraffin removal viscosity reducer

Abstract

The invention relates to the technical field of oilfield chemistry, in particular to a paraffin removal viscosity reducer for hydraulic jet paraffin removal and a use method thereof, the paraffin removal viscosity reducer for hydraulic jet paraffin removal comprises the following raw materials in percentage by mass: 0.1-0.5% of octadecanol, 5-10% of eicosyl heavy mahogany petroleum sulfonate, 5-20% of ethanol, 1-5% of polyethylene oxide surfactant, 10-20% of betaine surfactant, 0.1-0.2% of hydroxyethyl cellulose and the balance of water. And the paraffin removal viscosity reducer is used for adding a required amount of the paraffin removal viscosity reducer into a working medium to obtain a paraffin removal working solution, the paraffin removal working solution is injected into the light casing oil well in a 10-13MPa hydraulic jet fluid form, and the paraffin deposits on the casing wall of the light casing oil well are cleaned by using the hydraulic jet fluid. The paraffin removal and viscosity reduction agent disclosed by the invention is simple in preparation method, can achieve a synergistic effect with a hydraulic jet fluid technology, and can maintain efficient paraffin removal and viscosity reduction performance in a high-salinity and high-specific-gravity slurry or solid-free well killing fluid environment.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and is a wax-removing and viscosity-reducing agent for hydraulic jet wax removal, as well as its preparation and application methods. Background Technology

[0002] During oil extraction, flowing wells, especially those using bare casing, are prone to paraffin wax deposition on their casing walls. If this wax is not thoroughly removed, it can affect the operation of the pumping unit, causing rod jamming or shutdown. As oil extraction progresses, paraffin wax from deeper formations is released along with the crude oil. Paraffin wax from deeper oil deposits typically contains large amounts of colloids and bituminous substances, resulting in strong adhesion, high plasticity, and a high melting point (80℃), forming a hard and difficult-to-remove composite deposit (casing wax). Traditional methods such as hot washing and mechanical scraping have limited effectiveness in removing this type of wax and can easily damage the formation or disrupt normal production.

[0003] Hydraulic jetting, as a physical method of paraffin removal, offers advantages such as high efficiency and zero pollution. However, for deep paraffin layers with high plasticity, strong adhesion, and high melting points, the impact force of water jets alone is often insufficient to completely peel and break them off. More importantly, for oil wells with high formation pressure, high-density mud or solids-free kill fluids must be used as the water jetting medium to balance formation pressure and ensure operational safety, rather than using clean water directly. These kill fluid systems have complex compositions, which significantly affect the chemical properties of conventional surfactant-based paraffin removers, causing problems such as salting out, flocculation, and failure, resulting in a significant reduction in the effectiveness of chemical paraffin removal. In actual operations, this often manifests as the paraffin removal tools encountering obstacles when being lowered into the well, making the operation impossible.

[0004] Chinese patent document CN115975611B discloses a paraffin inhibitor for drilling fluids, its preparation method, and its application. The paraffin inhibitor comprises, by weight, 1-10 parts of a lipophilic surfactant; 3-15 parts of a main agent; and 80-95 parts of an organic solvent. The lipophilic surfactant is selected from at least one of the Span series and OP series surfactants, and the main agent is selected from a specific type of binary polymer copolymer. The paraffin inhibitor provided by this invention not only has good paraffin inhibition rate and paraffin dissolution rate but also does not adversely affect the performance of the drilling fluid. However, the petroleum ether organic solvent used in this invention has a boiling range of 90℃-120℃. This type of petroleum ether belongs to the first category of highly flammable liquids, has a low flash point, is flammable and explosive, and is easily volatile. Production must be carried out in a closed system; otherwise, it can easily lead to waste of reagents, environmental pollution, and personnel poisoning.

[0005] Therefore, developing a chemical agent and method that can work synergistically with hydraulic jet technology and maintain efficient wax removal and viscosity reduction performance in high-salinity, high-density mud or solid-free well control fluid environments has become a pressing technical challenge in this field. Summary of the Invention

[0006] This invention provides a wax-removing and viscosity-reducing agent for hydraulic jet wax removal, as well as its preparation and application method, which overcomes the shortcomings of the prior art. It can effectively solve the problem that the casing wax with strong adhesion, high plasticity and high melting point is difficult to clean and has a poor removal effect during the production of oil wells with bare casing, thus affecting the normal production of oil wells.

[0007] One of the technical solutions of this invention is achieved through the following measures: A wax-removing and viscosity-reducing agent for hydraulic jet wax removal, comprising, by mass percentage: 0.1% to 0.5% octadecyl alcohol, 5% to 10% eicosyl heavy petroleum sulfonate, 5% to 20% ethanol, 1% to 5% polyethylene oxide surfactant, 10% to 20% betaine surfactant, 0.1% to 0.2% hydroxyethyl cellulose, with the balance being water, prepared according to the following method: Under stirring, the required amount of water is first added, and then the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol, and hydroxyethyl cellulose are added sequentially to obtain a mixed system. The mixture is stirred until it is uniform and transparent to obtain the wax-removing and viscosity-reducing agent for hydraulic jet wax removal.

[0008] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The degree of polymerization of the aforementioned polyethylene oxide surfactant is between 2000 and 10000.

[0009] The aforementioned betaine surfactants are one or more of cocamidopropyl betaine, dodecyl dimethyl betaine, and octadecyl dimethyl betaine.

[0010] The second technical solution of the present invention is achieved through the following measures: A method for preparing a wax remover and viscosity reducer for hydraulic jet wax removal is carried out according to the following steps: Under stirring, the required amount of water is added first, and then the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol, and hydroxyethyl cellulose are added in sequence to obtain a mixed system. The mixture is stirred until it is uniform and transparent to obtain the wax remover and viscosity reducer for hydraulic jet wax removal.

[0011] The third technical solution of the present invention is achieved through the following measures: a method for using a wax remover and viscosity reducer for hydraulic jet wax removal, comprising the following steps: S1: Prepare the working medium based on the wax deposition condition of the oil well and the formation pressure; S2: Add the required amount of hydraulic jet wax remover and viscosity reducer to the working medium prepared in step S1, mix evenly, and obtain the wax removal working fluid; S3: Inject the wax removal working fluid obtained in step S2 into the bare casing oil well to generate hydraulic jet fluid, and use the hydraulic jet fluid to clean the wax deposits on the casing wall of the bare casing oil well. S4: Repeat step S3 to perform a circulating dewaxing operation until the dewaxing fluid carrying broken wax blocks returns out of the wellbore.

[0012] The following are further optimizations and / or improvements to the third technical solution of the above invention: In step S1 above, the working medium is one of oilfield treatment water, mud, or solids-free well control fluid.

[0013] The density range of the above-mentioned mud is 1.3 g / cm³. 3 Up to 1.6 g / cm 3 The raw material for solid-free kill fluid is either sodium chloride solution or calcium chloride solution, and the density range of the solid-free kill fluid is 1.0 g / cm³. 3 Up to 1.6 g / cm 3 .

[0014] In step S2 above, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.1% to 6% of the total volume of the wax removal working fluid.

[0015] In step S2 above, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.5% to 5% of the total volume of the wax removal working fluid.

[0016] In step S3 above, the pressure of the hydraulic jet fluid is 1 MPa to 15 MPa, and the injection flow rate of the hydraulic jet fluid is 0.3 m³ / s. 3 / min to 0.6m 3 / min.

[0017] This invention involves injecting a wax-removing working fluid into a bare casing well as a hydraulic jet at a pressure of 10 MPa to 13 MPa, thereby cleaning wax deposits from the casing wall. The method for preparing the wax-removing and viscosity-reducing agent for hydraulic jet wax removal in this invention is simple, it can work synergistically with hydraulic jet technology, and it maintains high-efficiency wax-removing and viscosity-reducing performance in high-salinity, high-specific-gravity mud or solids-free kill fluid environments. Detailed Implementation

[0018] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solution of this invention and the actual situation. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; room temperature in this invention generally refers to a temperature between 15°C and 25°C, and is generally defined as 25°C.

[0019] The present invention will be further described below with reference to embodiments: Example 1: This hydraulic jet dewaxing and viscosity reducing agent comprises, by mass percentage: 0.1% to 0.5% octadecyl alcohol, 5% to 10% eicosyl heavy petroleum sulfonate, 5% to 20% ethanol, 1% to 5% polyethylene oxide surfactant, 10% to 20% betaine surfactant, 0.1% to 0.2% hydroxyethyl cellulose, with the balance being water. It is prepared by the following method: Under stirring, the required amount of water is added first, followed by the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol, and hydroxyethyl cellulose in sequence to obtain a mixed system. The mixture is stirred until it is uniform and transparent, thus obtaining the hydraulic jet dewaxing and viscosity reducing agent.

[0020] This invention constructs a multifunctional synergistic system. Ethanol and octadecyl alcohol act as penetrants, enabling rapid penetration into the interior of the wax; polyethylene oxide surfactants provide excellent wetting properties and reduce interfacial tension; betaine surfactants exhibit excellent resistance to salts and calcium and magnesium ions, and their stability is further enhanced when compounded with eicosyl heavy petroleum sulfonate.

[0021] Example 2: As an optimization of the above example, the degree of polymerization of the polyethylene oxide surfactant is 2000 to 10000.

[0022] Depending on the requirements, highly polymerized polyethylene oxide can also act as a thickener and wax carrier, enhancing the jet impact force and wax carrying capacity.

[0023] Example 3: As an optimization of the above examples, the betaine surfactant is one or more of cocamidopropyl betaine, dodecyl dimethyl betaine, and octadecyl dimethyl betaine.

[0024] Example 4: The preparation method of the dewaxing and viscosity reducing agent for hydraulic jet dewaxing is carried out according to the following steps: Under stirring, the required amount of water is added first, and then the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol and hydroxyethyl cellulose are added in sequence to obtain a mixed system. The mixture is stirred until it is uniform and transparent to obtain the dewaxing and viscosity reducing agent for hydraulic jet dewaxing.

[0025] Example 5: The application method of this hydraulic jet wax remover and viscosity reducer is as follows: S1: Prepare the working medium based on the wax deposition condition of the oil well and the formation pressure; S2: Add the required amount of hydraulic jet wax remover and viscosity reducer to the working medium prepared in step S1, mix evenly, and obtain the wax removal working fluid; S3: Inject the wax removal working fluid obtained in step S2 into the bare casing oil well to generate hydraulic jet fluid, and use the hydraulic jet fluid to clean the wax deposits on the casing wall of the bare casing oil well. S4: Repeat step S3 to perform a circulating dewaxing operation until the dewaxing fluid carrying broken wax blocks returns out of the wellbore.

[0026] Example 6: As an optimization of the above example, in step S1, the working medium is one of oilfield treatment water, mud, or solids-free well control fluid.

[0027] Example 7: As an optimization of the above examples, the density of the mud is in the range of 1.3 g / cm³. 3 Up to 1.6 g / cm 3 The raw material for the solid-free kill fluid is either sodium chloride solution or calcium chloride solution, and the density range of the solid-free kill fluid is 1.0 g / cm³. 3 Up to 1.6 g / cm 3 .

[0028] Depending on the requirements, the main raw material components of the mud include water, bentonite, barite powder, and iron ore powder.

[0029] Example 8: As an optimization of the above example, in step S2, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.1% to 6% of the total volume of the wax removal working fluid.

[0030] Example 9: As an optimization of the above example, in step S2, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.5% to 5% of the total volume of the wax removal working fluid.

[0031] Example 10: As an optimization of the above embodiment, in step S3, the pressure of the hydraulic jet fluid is 1 MPa to 15 MPa, and the injection flow rate of the hydraulic jet fluid is 0.3 m³ / s. 3 / min to 0.6m 3 / min.

[0032] Example 11: 596 kg of water was first added to a stirred reactor, followed by 70 kg of sodium eicosyl heavy petroleum sulfonate, 150 kg of cocamidopropyl betaine, 30 kg of polyethylene oxide surfactant with a degree of polymerization of 4000, 3 kg of octadecyl alcohol, 150 kg of ethanol, and 1 kg of hydroxyethyl cellulose. The mixture was stirred until completely dissolved and stirred for another 30 minutes until the mixture was uniform and transparent. This yielded a dewaxing and viscosity-reducing agent for hydraulic jet dewaxing, denoted as dewaxing and viscosity-reducing agent A.

[0033] Example 12: The difference between Example 12 and Example 11 is that the raw materials added to the reactor are: 548 kg water, 100 kg sodium eicosyl heavy petroleum sulfonate, 100 kg dodecyl dimethyl betaine, 50 kg polyethylene oxide surfactant with a degree of polymerization of 8000, 1 kg octadecyl alcohol, 200 kg ethanol, and 1 kg hydroxyethyl cellulose, to obtain a dewaxing and viscosity reducing agent for hydraulic jet dewaxing, denoted as dewaxing and viscosity reducing agent B.

[0034] Example 13: The difference between Example 13 and Example 11 is that the raw materials added to the reactor are: 634 kg water, 50 kg sodium eicosyl heavy petroleum sulfonate, 200 kg octadecyl dimethyl betaine, 10 kg polyethylene oxide surfactant with a degree of polymerization of 2500, 5 kg octadecyl alcohol, 100 kg ethanol, and 1 kg hydroxyethyl cellulose, to obtain a dewaxing and viscosity reducing agent for hydraulic jet dewaxing, denoted as dewaxing and viscosity reducing agent C.

[0035] Example 14: In a bare casing oil well with a casing depth of 3178.63m, during paraffin removal operations, the paraffin removal tools were lowered to 247.26m and 3105.2m respectively, but both were blocked by paraffin wax. Before well workover, a 60m... 3 105℃ hot water was used for well washing and wax removal; pump truck pressure was 4MPa; injection flow rate was 0.2m³ / h. 3 / min, no wax return observed; high-pressure jet cleaning was used during well workover, employing a 50m... 3 1.4g / cm 3 The mud was used as the working medium, with an injection flow rate of 0.5 m³ / h. 3 At a pressure of 13 MPa and a flow rate of 100 m / min, no paraffin wax was returned after 13 hours of cyclical operation. The paraffin wax in this well has a melting point of 91°C, contains 38% colloids and bituminous substances, and is highly viscous. Conventional methods such as hydraulic jetting, hot water, and scraping to remove the wax were all ineffective.

[0036] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, a concentration of 1.4 g / cm³ is adopted. 3 The working medium for preparing mud; S2: 2m 3The wax-reducing and viscosity-reducing agent A prepared in Example 11 was added to 50m 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.5m. 3 A flow rate of 100 m / min was injected into the bare casing well at a pressure of 13 MPa to remove wax deposits from the casing wall. The wax removal tool was lowered to the top of the oil layer at 3105.2 m without obstruction, and the wax removal work took a total of 13 hours.

[0037] Example 15: A smooth-casing oil well with a casing depth of 3458.27m. The paraffin melting point of this well is 89℃, and the paraffin contains 32% gum and bituminous substances. Wax buildup occurred in the tubing, causing the smooth rod to become stuck. During the wax removal operation, 60m of... 3 Room temperature water, injection flow rate 0.6m 3 / min well washing 100min, maximum construction pump pressure 8MPa, not yet disconnected; 60m 3 Hot water at 105℃, injection flow rate 0.2m. 3 The well was cleaned for 300 minutes at a rate of 1000 min, with a maximum pump pressure of 2.5 MPa during construction. The pump was not disconnected.

[0038] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, use 1.0 g / cm³. 3 Oilfield treated water preparation working medium; S2: 0.5m 3 The wax-reducing and viscosity-reducing agent A prepared in Example 11 was added to 50m 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.6m. 3 Injected into a bare casing well at a flow rate of / min, with an injection pressure of 5MPa, and a wax removal working volume of 30m³. 3 At that time, the sucker rod moved up and down normally; the wax deposits on the well casing wall were completely removed in 85 minutes.

[0039] Example 16: A bare casing oil well with a casing depth of 3100m was dewaxed using hydraulic jet fluid from ambient temperature oilfield treatment water at a pump pressure of 15MPa and a pump injection flow rate of 0.5m³ / min. 3 / min, no paraffin returned, the paraffin removal tool encountered resistance at 800m downhole, the casing was blocked by paraffin, the operation time was 15 hours; replace with 106℃ hot water hydraulic jet fluid, pump pressure 15MPa, pump injection flow rate 0.5m 3At a rate of 1000 m / min, no paraffin was returned after 10 hours of operation. The high-pressure jetting nozzle and tubing were stuck at 800 m, making it impossible to lower or raise them. The paraffin in this well has a melting point of 89°C and contains 32% gum and bituminous substances. It is highly viscous, and conventional methods such as hydraulic jetting fluid, hot water, or scraping to remove the paraffin have been ineffective.

[0040] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, use 1.0 g / cm³. 3 Oilfield treated water preparation working medium; S2: 4.8m 3 The wax-reducing and viscosity-reducing agent A prepared in Example 11 was added to 80m 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.5m. 3 The injection flow rate was injected into the bare casing well at a pressure of 8 MPa to clean the wax deposits on the casing wall. After 12 hours of operation, the wax removal tool was successfully lowered to 2900m and a large amount of paraffin wax was returned.

[0041] Example 17: A certain smooth casing oil well, with a casing depth of 693.19m, 50m of 105℃ hot water was poured in. 3 Injection flow rate: 0.4 m³ / s 3 The well is circulated at a rate of / min, with a maximum pump pressure of 5MPa, and the operation lasts for 125 minutes until clean water returns from the wellhead. Then, a 30m... 3 1.2g / cm 3 A circulating hydraulic jet of calcium chloride brine at room temperature is used for dewaxing, with a pump pressure of 12 MPa and an injection flow rate of 0.5 m³ / h. 3 / min, 12 hours of construction, no paraffin wax returned; then the electrical testing instrument showed no data, the instrument was blocked by wax; replaced with 30m 3 1.2 g / cm³ at 105℃ 3 The calcium chloride brine jet circulation was used for dewaxing, with a pump pressure of 12 MPa and an injection flow rate of 0.3 m³ / h. 3 At a rate of 94°C / min, after 12 hours of operation, no paraffin wax was returned. The paraffin wax in this well has a melting point of 94°C and contains 36% colloids and bituminous substances. It is highly viscous, and conventional methods such as hydraulic jetting, hot water, or scraping to remove the wax are all ineffective.

[0042] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, a concentration of 1.2 g / cm³ is adopted. 3 Calcium chloride brine is used to prepare the working medium; S2: Add 0.6 m3 of the wax-removing and viscosity-reducing agent A prepared in Example 11 to 30 m3 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.5m. 3 The injection flow rate was injected into the bare casing well at a pressure of 10 MPa to clean the wax deposits on the casing wall. After 4 hours of operation, the wax removal tool was successfully lowered to 693.19m and a large amount of viscous paraffin was returned.

[0043] Example 18: A certain smooth casing oil well, with a casing depth of 1040m, using 40m... 3 The well was flushed with 105℃ hot water at a pump pressure of 3MPa and an injection flow rate of 0.3m³ / h. 3 / min, until clean water returns from the wellhead; during well workover, run the casing scraper with a high-pressure jet integrated tool at the tail, using a 30m... 3 1.18 g / cm 3 High-pressure jet dewaxing was performed using circulating sodium chloride brine, with a pump pressure of 12 MPa and an injection flow rate of 0.5 m³ / h. 3 The flow rate was 10.5 m / min, the working time was 14 hours, and the jetting nozzle reached 1040 m. No paraffin was observed to return during the entire wax removal process. Then, the packer encountered resistance at 433.33 m and was sealed by wax. The paraffin in this well has a melting point of 94℃, and the paraffin contains 27% gum and bituminous substances. It is highly viscous, and conventional methods such as hydraulic jetting, hot water, or scraping for wax removal were all ineffective.

[0044] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, a concentration of 1.15 g / cm³ is adopted. 3 The working medium is prepared from sodium chloride brine. S2: 0.9m 3 The wax-reducing and viscosity-reducing agent B prepared in Example 12 was added to 30m 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.5m. 3 The injection flow rate was injected into the bare casing well at a pressure of 12 MPa to clean the wax deposits on the casing wall. After 8 hours of operation, the wax removal tool was successfully lowered to 1040m and a large amount of viscous paraffin wax was returned.

[0045] Example 19: A casing oil well in Xinjiang, with a casing depth of 3044m, used an integrated tool with a scraper tail and high-pressure jet, employing a 50m... 3 1.3g / cm3 During the mud circulation dewaxing operation, the pump pressure was 12 MPa, and no paraffin was returned after 18 hours of operation. The high-pressure jet instrument encountered resistance at 1208m, becoming coated with paraffin and malfunctioning, requiring a shutdown. The paraffin in this well has a melting point of 87℃, contains 31% gum and bituminous substances, and is highly viscous. Conventional hydraulic jetting, hot water, or scraping methods for dewaxing were all ineffective.

[0046] Perform wax removal operations on the above-mentioned bare casing oil wells according to the following method of using the wax remover and viscosity reducer for hydraulic jet wax removal: S1: Based on the wax deposition in the oil well and the formation pressure, a concentration of 1.3 g / cm³ is adopted. 3 The working medium for preparing mud; S2: 2m 3 The wax-reducing and viscosity-reducing agent B prepared in Example 12 was added to 50m 3 The working medium obtained in step S1 is mixed evenly to obtain a wax removal working solution; S3: Lower the high-definition wax removal tool downhole, and use a pump truck to pump the wax removal working fluid obtained in step S2 at a rate of 0.5m. 3 The injection flow rate was injected into the bare casing well at a pressure of 12 MPa. Under normal temperature conditions, a circulating dewaxing operation was carried out. After 13 hours of operation, the dewaxing tool was successfully lowered to 3044m, and a large amount of viscous paraffin was returned.

[0047] The wax removal operations of Examples 14 to 19 were compared, and the comparison data is shown in Table 1. As can be seen from Table 1, for oil wells with high content of gum and asphaltene in the wax deposits on the casing wall and strong viscosity, the wax removal effect of conventional wax removal methods is low due to wax blockage. However, the wax removal and viscosity reduction agent of the present invention for hydraulic jet wax removal, combined with jet fluid wax removal, achieves the expected wax removal effect.

[0048] In summary, the wax removal and viscosity reducing agent for hydraulic jet wax removal of the present invention has excellent compatibility and stability: the betaine surfactant in the raw materials has excellent resistance to salt and calcium and magnesium ions, and its stability is further enhanced after being compounded with eicosyl heavy petroleum sulfonate, so that it does not precipitate or settle in high-density, high-mineralization mud or solid-free kill fluid, and its performance is stable. It successfully solves the production problems such as the obstruction of wax removal tools when going down into the well due to stubborn wax blockage in deep wells. The technical effect is significant and it has good industrial application value.

[0049] The above technical features constitute various embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A wax-removing and viscosity-reducing agent for hydraulic jet wax removal, characterized in that... The raw materials, by mass percentage, include: 0.1% to 0.5% octadecyl alcohol, 5% to 10% eicosyl heavy petroleum sulfonate, 5% to 20% ethanol, 1% to 5% polyethylene oxide surfactant, 10% to 20% betaine surfactant, 0.1% to 0.2% hydroxyethyl cellulose, and the balance being water. The mixture is prepared as follows: Under stirring, the required amount of water is added first, followed by the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol, and hydroxyethyl cellulose in sequence to obtain a mixed system. The mixture is stirred until it is uniform and transparent, yielding a dewaxing and viscosity-reducing agent for hydraulic jet dewaxing.

2. The dewaxing and viscosity-reducing agent for hydraulic jet dewaxing according to claim 1, characterized in that... The degree of polymerization of polyethylene oxide surfactants ranges from 2,000 to 10,000.

3. The dewaxing and viscosity-reducing agent for hydraulic jet dewaxing according to claim 1 or 2, characterized in that... The betaine surfactant is one or more of cocamidopropyl betaine, dodecyl dimethyl betaine, and octadecyl dimethyl betaine.

4. A method for preparing a dewaxing and viscosity reducing agent for hydraulic jet dewaxing according to any one of claims 1 to 3, characterized in that... The following steps are to be performed: Under stirring, first add the required amount of water, then add the required amounts of eicosyl heavy petroleum sulfonate, betaine surfactant, polyethylene oxide surfactant, octadecyl alcohol, ethanol, and hydroxyethyl cellulose in sequence to obtain a mixed system. Stir until the mixed system is uniform and transparent to obtain a dewaxing and viscosity reducing agent for hydraulic jet dewaxing.

5. A method of using the hydraulic jet wax remover and viscosity reducer according to any one of claims 1 to 3, characterized in that... Follow these steps: S1: Prepare the working medium based on the wax deposition condition of the oil well and the formation pressure; S2: Add the required amount of hydraulic jet wax remover and viscosity reducer to the working medium prepared in step S1, mix evenly, and obtain the wax removal working fluid; S3: Inject the wax removal working fluid obtained in step S2 into the bare casing oil well to generate hydraulic jet fluid, and use the hydraulic jet fluid to clean the wax deposits on the casing wall of the bare casing oil well. S4: Repeat step S3 to perform a circulating dewaxing operation until the dewaxing fluid carrying broken wax blocks returns out of the wellbore.

6. The method of using the wax remover and viscosity reducer for hydraulic jet wax removal according to claim 5, characterized in that... In step S1, the working medium is one of oilfield treatment water, mud, or solids-free well control fluid.

7. The method of using the wax remover and viscosity reducer for hydraulic jet wax removal according to claim 6, characterized in that... The density of the mud ranges from 1.3 g / cm³ to 1.6 g / cm³. The raw material for the solid-free kill fluid is either sodium chloride solution or calcium chloride solution, and the density of the solid-free kill fluid ranges from 1.0 g / cm³ to 1.6 g / cm³.

8. The method of using the wax-removing and viscosity-reducing agent for hydraulic jet wax removal according to claim 5, 6, or 7, characterized in that... In step S2, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.1% to 6% of the total volume of the wax removal working fluid.

9. The method of using the wax-removing and viscosity-reducing agent for hydraulic jet wax removal according to claim 5, 6, 7, or 8, characterized in that... In step S2, the amount of wax remover and viscosity reducer added for hydraulic jet wax removal is 0.5% to 5% of the total volume of the wax removal working fluid.

10. The method of using the wax-removing and viscosity-reducing agent for hydraulic jet wax removal according to claim 5, 6, 7, 8, or 9, characterized in that... In step S3, the pressure of the hydraulic jet fluid is 1 MPa to 15 MPa, and the injection flow rate of the hydraulic jet fluid is 0.3 m³ / min to 0.6 m³ / min.

Images