Wax crystal inhibitor for oil and gas production and preparation method thereof
The prepared wax crystal inhibitor breaks down wax crystal scale, prevents wax crystal aggregation, and lowers the freezing point, solving the problems of narrowed flow channels and increased viscosity caused by wax crystal precipitation during oilfield extraction. It achieves a highly efficient wax-prevention and viscosity-reducing effect, reducing construction risks and energy consumption.
Patent Information
- Application Number
- CN202511088174.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-05
- Publication Date
- 2025-11-11
AI Technical Summary
In the process of oilfield extraction, the precipitation of wax crystals leads to a narrowing of the crude oil flow channel and an increase in viscosity, causing difficulties in extraction and transportation. Moreover, existing wax removal methods are energy-intensive, have high construction risks, and are not very effective.
The wax crystal inhibitor is composed of an oily solvent, a wax crystal modifier, a penetrant, and a surfactant. It works by breaking down wax crystal scale, preventing wax crystal aggregation, and lowering the freezing point. It is applied using a skid-mounted device or a pump injection method to promote the entry of the wax crystal inhibitor into the wax crystal molecular structure.
It effectively prevents wax crystal aggregation, lowers the pour point of crude oil, improves fluidity, solves the problem of difficult oil well extraction and transportation, and at the same time has high construction safety, reduces energy consumption, and has a significant anti-wax effect.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of oilfield chemical technology, specifically to a wax crystal inhibitor for oil and gas production and its preparation method. Background Technology
[0002] During oilfield extraction, as crude oil is extracted from the wellbore to the surface, changes in temperature and pressure lead to gas release, temperature drop, and pressure reduction. This causes wax and asphaltene in the crude oil to precipitate and adhere to the tubing and sucker rod surfaces, clogging the produced fluid pathways, increasing the well load, raising crude oil viscosity, and increasing surface pipeline pressure. These problems result in decreased oil well production. Currently, the most common wax removal methods are hot washing and chemical wax removal. Hot washing generally requires a temperature above 100℃. Specialized equipment is required, which is energy-intensive due to significant heat loss from the wellhead downwards. Furthermore, the quality of the water used causes severe scaling and corrosion, increasing costs. Chemical wax removal and prevention methods include oil-based wax removers and surfactant-based wax prevention. Oil-based wax removers are affected by the chemical properties and dosage, which can lead to incomplete wax removal and pose significant safety risks. Surfactant-based wax prevention has a lower wax prevention rate and is limited by application conditions, requiring continuous dripping for optimal results, but it still doesn't achieve the desired wax prevention effect.
[0003] Therefore, a wax crystal inhibitor was developed to prevent wax precipitation by altering wax crystal scaling. At the same time, the wax crystal inhibitor can effectively lower the pour point of crude oil. Lowering the pour point of crude oil while preventing wax deposition improves crude oil fluidity and plays a role in cleaning and preventing wax deposition in oil wells, thus aiding in oil well extraction. Summary of the Invention
[0004] This invention provides a wax crystal inhibitor for oil and gas production and its preparation method, which overcomes the shortcomings of the prior art. It can effectively solve the problems of wax precipitation and adsorption on the pipe wall during the production of high wax-content oil wells, which causes narrowing of the crude oil flow channel, wax crystal precipitation and increased crude oil viscosity, resulting in difficulties in production and transportation.
[0005] One of the technical solutions of the present invention is achieved through the following measures: a wax crystal inhibitor for oil and gas production, wherein the raw materials include, by mass, 60 to 65 parts of oily solvent, 10 to 15 parts of wax crystal modifier, 5 to 10 parts of penetrant and 10 to 15 parts of surfactant.
[0006] The following are further optimizations and / or improvements to the above-mentioned technical solution: The aforementioned oily solvent is D-limonene or xylene.
[0007] The aforementioned wax crystal modifier is EVA (ethylene-vinyl acetate copolymer).
[0008] The aforementioned penetrant is dodecylbenzenesulfonic acid.
[0009] The surfactant mentioned above is cashew phenol polyoxyethylene ether.
[0010] The above-mentioned wax crystal inhibitor for oil and gas recovery was prepared according to the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
[0011] The second technical solution of the present invention is achieved through the following measures: a method for preparing a wax crystal inhibitor for oil and gas production, comprising the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
[0012] This invention provides a wax crystal inhibitor for oil and gas production and its preparation method. Through the interaction of components in the raw materials, the wax crystal inhibitor enters the wax crystal molecular structure before wax precipitation in the oil well, disrupting wax crystal scaling and preventing wax aggregation and precipitation. This effectively solves the problem of difficult oil well extraction and transportation caused by wax formation in high-wax oil wells, preventing wax crystal aggregation and adsorption, and allowing wax to be extracted with the fluid flow. Furthermore, it has good compatibility with field demulsifiers and does not affect crude oil dehydration. Detailed Implementation
[0013] This invention is not limited to the following embodiments, and specific implementation methods can be determined according to the technical solutions and actual conditions of this invention. Unless otherwise specified, all chemical reagents and chemicals mentioned in this invention are well-known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent, for example, hydrochloric acid solution is an aqueous solution of hydrochloric acid; room temperature in this invention generally refers to a temperature between 15°C and 25°C, generally defined as 25°C.
[0014] The present invention will be further described below with reference to embodiments: Example 1: A wax crystal inhibitor for oil and gas production, comprising the following raw materials by mass: 60 to 65 parts of oily solvent, 10 to 15 parts of wax crystal modifier, 5 to 10 parts of penetrant and 10 to 15 parts of surfactant.
[0015] Example 2: As an optimization of the above examples, the oily solvent is D-limonene or xylene.
[0016] Example 3: As an optimization of the above examples, the wax crystal modifier is EVA (ethylene-vinyl acetate copolymer).
[0017] Example 4: As an optimization of the above examples, the penetrant is dodecylbenzenesulfonic acid.
[0018] Example 5: As an optimization of the above examples, the surfactant is cashew phenol polyoxyethylene ether.
[0019] Example 6: The preparation method of this wax crystal inhibitor for oil and gas production includes the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
[0020] The raw materials of this invention use D-limonene or xylene as the oily solvent, which can fully dissolve EVA (ethylene-vinyl acetate copolymer); the raw materials of this invention use EVA (ethylene-vinyl acetate copolymer) as the wax crystal modifier, which can enter the wax crystal molecules, change the shape of the wax crystals, and prevent the wax crystals from agglomerating and growing; the raw materials of this invention use dodecylbenzene sulfonic acid as the penetrant, and cashew phenol polyoxyethylene ether as the surfactant, which can improve the penetration, wetting, emulsification, and dispersion of the agent, so that the agent can quickly enter between the wax crystal molecules, disperse the wax crystals, form isolation between the wax crystals, and prevent the wax crystals from agglomerating and growing. The raw materials of this invention are readily available and the components have good compatibility.
[0021] During construction, the on-site pumping pressure is slightly higher than the well casing pressure. The pumping rate is calculated based on the daily produced fluid volume of the well and the optimal dosage of the reagent selected through laboratory experiments. The pumping rate is adjusted accordingly. Based on a daily produced fluid volume of 20 cubic meters per well and an optimal reagent concentration of 1500 ppm selected through laboratory evaluation, the pumping rate is controlled at 1.25 L / h, with a total daily injection volume of 30 L. First, install a skid-mounted continuous chemical dosing system (including a chemical storage tank, dosing pump, dosing pipeline safety valve, pressure gauge, control valve, etc.) at the wellhead and verify the rated pressure of the wellhead tree. Then, add high-wax well wax crystal inhibitor to the chemical storage tank of the skid-mounted continuous chemical dosing system at the wellhead, connect the wellhead for pressure testing, start the pump for pressure testing, and begin injecting chemicals once the pressure test is passed. The amount of chemicals added is calculated and adjusted according to the actual needs on site. The pump flow rate can be controlled as follows: 0 kg / h to 3.8 kg / h, 0 kg / h to 15 kg / h, or 0 kg / h to 50 kg / h. The pump pressure can be controlled as follows: 0 MPa to 16 MPa, depending on the site conditions. Finally, observe the changes in pump injection pressure. Once the flow rate is determined and the pump injection pressure is stable, continue injecting chemicals to ensure that the chemicals are always maintained at the optimal concentration in the produced fluid, achieving the best anti-wax effect.
[0022] This invention relates to a wax crystal inhibitor, which is a wax crystal modified type of wax inhibitor. After being injected into an oil well, it mixes with the produced fluid and enters the wax crystal molecular structure before wax precipitates, thus disrupting wax crystal scaling and preventing wax aggregation and precipitation. Simultaneously, it alters the morphology of paraffin wax crystals, inhibiting the formation of a three-dimensional network structure through eutectic or adsorption interactions with polar groups, thereby reducing the apparent viscosity of the crude oil pour point and achieving a wax-preventing and viscosity-reducing effect.
[0023] Example 7: The wax crystal inhibitor for oil and gas production comprises the following raw materials by weight: 60 parts of oily solvent D-limonene, 15 parts of EVA (ethylene-vinyl acetate copolymer), 10 parts of penetrant dodecylbenzenesulfonic acid, and 15 parts of cashew phenol polyoxyethylene ether.
[0024] Add the required amount of EVA to D-limonene and stir until completely dissolved to obtain mixture one; then add the required amount of dodecylbenzenesulfonic acid to mixture one and mix evenly to obtain mixture two; after the system temperature returns to room temperature, add cashew phenol polyoxyethylene ether to mixture two and stir until completely dissolved to obtain wax crystal inhibitor for oil and gas production.
[0025] Example 8: The wax crystal inhibitor for oil and gas production comprises, by weight, 65 parts of oily solvent D-limonene, 10 parts of EVA (ethylene-vinyl acetate copolymer), 10 parts of penetrant dodecylbenzenesulfonic acid, and 15 parts of cashew phenol polyoxyethylene ether.
[0026] Add the required amount of EVA to D-limonene and stir until completely dissolved to obtain mixture one; then add the required amount of dodecylbenzenesulfonic acid to mixture one and mix evenly to obtain mixture two; after the system temperature returns to room temperature, add cashew phenol polyoxyethylene ether to mixture two and stir until completely dissolved to obtain wax crystal inhibitor for oil and gas production.
[0027] Example 9: The wax crystal inhibitor for oil and gas production comprises, by weight, 60 parts of the oily solvent xylene, 15 parts of EVA (ethylene-vinyl acetate copolymer), 10 parts of the penetrant dodecylbenzenesulfonic acid, and 15 parts of cashew phenol polyoxyethylene ether.
[0028] Add the required amount of EVA to xylene and stir until completely dissolved to obtain mixture one; then add the required amount of dodecylbenzenesulfonic acid to mixture one and mix evenly to obtain mixture two; after the system temperature returns to room temperature, add cashew phenol polyoxyethylene ether to mixture two and stir until completely dissolved to obtain wax crystal inhibitor for oil and gas production.
[0029] Example 10: The wax crystal inhibitor for oil and gas production includes, by weight, 60 parts xylene (an oily solvent), 10 parts EVA (ethylene-vinyl acetate copolymer), 5 parts dodecylbenzenesulfonic acid (a penetrant), and 15 parts cashew phenol polyoxyethylene ether.
[0030] Add the required amount of EVA to xylene and stir until completely dissolved to obtain mixture one; then add the required amount of dodecylbenzenesulfonic acid to mixture one and mix evenly to obtain mixture two; after the system temperature returns to room temperature, add cashew phenol polyoxyethylene ether to mixture two and stir until completely dissolved to obtain wax crystal inhibitor for oil and gas production.
[0031] Comparative Example 1: Surfactant wax inhibitor (polyether surfactant).
[0032] Comparative Example 2: The difference from Example 7 is that the penetrant dodecylbenzenesulfonic acid was not added.
[0033] Comparative Example 3: The difference from Example 7 is that cashew phenol polyoxyethylene ether is replaced with fatty alcohol polyoxyethylene ether.
[0034] Comparative Example 4: The difference from Example 7 is that the oil-soluble solvent D-limonene was replaced with acetone.
[0035] Test example: The wax crystal inhibitors for oil and gas production prepared in Examples 7 to 10 and the samples of Comparative Examples 1 to 4 were tested for wax prevention rate, viscosity reduction rate and pour point reduction rate under the same dosage.
[0036] Take 18 stoppered glass bottles and add 100g of oil sample to each bottle, with two bottles per group. One group serves as a blank sample. Add 2.5g of xylene to each stoppered glass bottle. For the other 8 groups, add the prepared samples of Examples 7 to 10 and Comparative Examples 1 to 4 to each group. Place the stoppered glass bottles in a water bath at 25°C above the wax precipitation point of the oil sample for 60 minutes, shake for 10 minutes, and then place them in a water bath at 5°C to 7°C above the wax precipitation point of the oil sample for 60 minutes. Measure the anti-wax rate and viscosity reduction rate using a testing machine.
[0037] Pour point drop determination: Take 9 stoppered glasses, one of which is a crude oil sample, and add 1500 ppm of the prepared sample solutions of Examples 7 to 10 and Comparative Examples 1 to 4 to the others. Determine the pour point according to the SY / T0541 standard and calculate the pour point drop.
[0038] As shown in Table 1, under the same dosage, Examples 7 to 10 achieved a wax prevention rate of over 60.7% and a viscosity reduction rate of over 38.5% for the crude oil in the field, with a pour point reduction of 20°C. Comparative Example 1, using a surfactant-based wax inhibitor, only achieved a wax prevention rate of 3.8% for the same oil sample. This surfactant-based wax inhibitor requires a crude oil water content between 50% and 60%, and only reduced the pour point by 1°C. Comparative Example 2 (without dodecylbenzene sulfonic acid) and Comparative Example 4 (using acetone as a solvent) showed significantly lower wax prevention rates, viscosity reduction rates, and pour point reductions compared to Example 7. Comparative Example 3, by replacing cashew phenol polyoxyethylene ether with fatty alcohol polyoxyethylene ether, showed a significant decrease in viscosity reduction, and the pour point reduction was also lower than that of Example 7.
[0039] In summary, the wax crystal inhibitor for oil and gas production of this invention promotes the entry of the inhibitor into the wax crystal molecular structure before wax precipitation in oil wells through the interaction of various components in the raw material. This disrupts wax crystal scaling, prevents wax aggregation and growth, and facilitates its precipitation. It can be applied using a skid-mounted device for continuous dripping or a truck-mounted pump injection method, effectively reducing pour point and preventing wax buildup. This effectively solves the problem of difficult oil well extraction and transportation caused by wax formation in high-wax oil wells, preventing wax crystal aggregation and adsorption, and allowing wax to be extracted with the liquid flow. Furthermore, it exhibits good compatibility with field demulsifiers and does not affect crude oil dehydration.
[0040] 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 crystal inhibitor for oil and gas recovery, characterized in that... The raw materials, by mass, include 60 to 65 parts of oily solvent, 10 to 15 parts of wax crystal modifier, 5 to 10 parts of penetrant and 10 to 15 parts of surfactant.
2. The wax crystal inhibitor for oil and gas production according to claim 1, characterized in that... The oily solvent is D-limonene or xylene.
3. The wax crystal inhibitor for oil and gas production according to claim 1 or 2, characterized in that... The wax crystal modifier is EVA.
4. The wax crystal inhibitor for oil and gas production according to claim 1 or 2, characterized in that... The penetrant is dodecylbenzenesulfonic acid.
5. The wax crystal inhibitor for oil and gas production according to claim 3, characterized in that... The surfactant is cashew phenol polyoxyethylene ether.
6. The wax crystal inhibitor for oil and gas production according to claim 1, 2, or 5, characterized in that... It is prepared according to the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
7. The wax crystal inhibitor for oil and gas production according to claim 3, characterized in that... It is prepared according to the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
8. The wax crystal inhibitor for oil and gas production according to claim 4, characterized in that... It is prepared according to the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.
9. A method for preparing a wax crystal inhibitor for oil and gas production according to any one of claims 1 to 5, characterized in that... Includes the following steps: Add the required amount of wax crystal modifier to the oily solvent and stir until completely dissolved to obtain mixture one; Add the required amount of penetrant to mixture one and mix well. Stir until completely dissolved to obtain mixture two. Add a surfactant to mixture 2 and stir until completely dissolved to obtain a wax crystal inhibitor for oil and gas production.