阅读说明：本技术 夹带剂辅助下超临界co2萃取钻井废弃物中油分的方法 (Supercritical CO with entrainer assistance2Method for extracting oil in drilling waste ) 是由 彭川 王涛 翟云波 于 2019-01-07 设计创作，主要内容包括：本发明公开了一种夹带剂辅助下超临界CO<Sub>2</Sub>萃取钻井废弃物中油分的方法。该方法包括以下步骤：S1、将钻井废弃物放入鼓风干燥箱中进行干燥,之后用粉碎机破碎；S2、将夹带剂与S1中得到的钻井废弃物混合,搅拌均匀,装入超临界萃取釜中；S3、将S2中得到的混合物进行超临界二氧化碳萃取,生成钻井废弃物的固态产物、液态混合物；S4、将S3中得到的液态混合物依次排入分离罐I和分离罐II进行分离,分离出油份；S5、萃取结束后,将S4中得到的油份从分离罐的底部收集。该方法能够显著提高钻井废弃物的含油萃取率,更大程度的回收残油,同时去除钻井废弃物中的重金属污染物,实现钻井废弃物的无害化和资源化处理。(The invention discloses supercritical CO with the assistance of an entrainer 2 A method for extracting oil from drilling waste. The method comprises the following steps: s1, placing the drilling waste into a forced air drying box for drying, and then crushing by a crusher; s2, mixing the entrainer with the drilling waste obtained in the step S1, uniformly stirring, and putting into a supercritical extraction kettle; s3, performing supercritical carbon dioxide extraction on the mixture obtained in the step S2 to generate a solid product and a liquid mixture of drilling waste; s4, sequentially discharging the liquid mixture obtained in the S3 into a separation tank I and a separation tank II for separation, and separating oil; and S5, after the extraction is finished, collecting the oil obtained in the S4 from the bottom of the separation tank. The method can obviously improve the oil extraction rate of the drilling waste, recover the residual oil to a greater extent, remove heavy metal pollutants in the drilling waste, and realize the harmless and recycling treatment of the drilling waste。)

1. Supercritical CO under entrainer assistance₂A method for extracting oil from drilling waste, comprising the steps of:

s1, placing the drilling waste into a forced air drying box for drying, and then crushing by a crusher;

s2, mixing the entrainer with the drilling waste obtained in the step S1, uniformly stirring, and putting into a supercritical extraction kettle;

s3, performing supercritical carbon dioxide extraction on the mixture obtained in the step S2 to generate a solid product and a liquid mixture of drilling waste;

s4, sequentially discharging the liquid mixture obtained in the S3 into a separation tank I and a separation tank II for separation, and separating oil;

and S5, after the extraction is finished, collecting the oil obtained in the S4 from the bottom of the separation tank.

2. The method according to claim 1, wherein the drying temperature in S1 is 40-50 ℃ and the drying time is 12-24 hours.

3. The method of claim 1, wherein the drilling waste in S1 is crushed to 60-80 mesh.

4. The method of claim 1, wherein the entrainer is one or a mixture of methanol and ethanol.

5. The method of claim 4, wherein the methanol solution has a concentration of 99.9% and the ethanol solution has a concentration of 99.5%.

6. The method of claim 1, wherein the mass ratio of the entrainer to the drilling waste in S2 is 0-1: 9, not including 0.

7. The method of claim 1, wherein the stirring speed is 100 to 120 r/min.

8. The method according to claim 7, wherein the stirring time is 1 to 2 hours.

9. The method of claim 1, wherein the supercritical carbon dioxide extraction temperature in S3 is 50 ℃.

10. The method according to claim 1, wherein the supercritical carbon dioxide extraction pressure in S3 is 14-20 MPa.

11. The method of claim 1, wherein the supercritical carbon dioxide extraction in S3 has a carbon dioxide flow rate of 30L/h and an extraction time of 80 minutes.

12. The method according to claim 1, wherein the mixture is discharged into separation tank I and separation tank II in sequence by a circulation pump in S4.

13. The method according to claim 1, wherein the pressure of the separation tank I in S4 is 8-10MPa, and the separation temperature is 50 ℃.

14. The method according to claim 12, wherein the pressure of the separation tank II is 6-8MPa and the separation temperature is 30 ℃.

15. The method of claim 1, wherein in S4, the solid product in the extraction tank is removed after carbon dioxide in the extraction tank is exhausted.

Technical Field

The invention belongs to the technical field of oil extraction, and particularly relates to supercritical CO with the assistance of an entrainer₂A method for extracting oil from drilling waste.

Background

Oil-based drilling waste is a byproduct generated during oil drilling operations under conditions using oil-based drilling fluids, and mainly includes drilling waste water and drill cuttings. The pollutant has high concentration and special property, and the main pollutant components are organic pollutant and petroleum matter, including phenol, benzene series, anthracene, , etc. If not properly treated, oil-based drilling waste can have an impact on the environmental ecology of soil, water, organisms, etc. after a series of physical, chemical and biological actions. Meanwhile, the oil-based drilling solid waste is high in petroleum-containing substances, the oil content is generally 10% -50%, and the oil-based drilling solid waste is a precious recyclable resource. Therefore, how to reduce, recycle and harmlessly treat the drilling waste, reduce the damage of the drilling waste to the environment as much as possible and recover the petroleum resources in the drilling waste becomes a problem to be solved in the oil and gas field exploration and development process.

At present, the common drilling waste treatment methods at home and abroad comprise: curing treatment, thermal distillation, bioremediation, dehydration backfill, solvent extraction, etc. Although they are effective in treating contaminants or recovering oil to some extent, they have certain limitations. The thermal distillation method and the steam stripping method have high requirements on equipment and high treatment cost, the solidification treatment method and the dehydration backfill method have the hidden danger of pollution of percolate and sludge, the operation cycle time of the bioremediation method is long, and the selectivity to strains is strong. The solvent extraction method is suitable for recovering oil from oil-based drilling waste, but the organic solvent has high volatility and high toxicity, and can generate great harm to human health and the surrounding environment.

Supercritical carbon dioxide extraction is a technique that uses carbon dioxide fluid above the critical temperature and critical pressure as an extractant. By virtue of the advantages of high selectivity, strong dissolving capacity, mild operation conditions, high efficiency, energy conservation, environmental protection and the like, the supercritical carbon dioxide extraction has a very good development prospect in the fields of food industry, Chinese herbal medicine development, polymer science and the like. The supercritical carbon dioxide extraction method is adopted to treat the oil-based drilling waste, the operation condition is moderate, secondary pollution can not be generated safely, and the useful part in the oil-based drilling waste can be well recovered. The research on the treatment of oil-based drilling waste by a supercritical carbon dioxide extraction method is still in a preliminary stage in China, the performance of the research is mainly optimized by changing pressure and temperature in the existing research, but few methods are available for increasing the contact between supercritical carbon dioxide and drilling fluid waste to improve the extraction rate. Therefore, the addition of a proper entrainer can be selected to increase the contact area of the supercritical carbon dioxide and the drilling fluid waste.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a drilling waste treatment method which has the advantages of better treatment effect, higher oil recovery rate, simple and safe operation and more environment-friendly property.

In order to solve the technical problem, the invention provides supercritical CO with the assistance of an entrainer₂The method for extracting oil from drilling waste has oil extracting rate of 30.10-92.20% and residual oil rate of 0.94-8.4% in the solid drilling waste.

The invention specifically adopts the following technical scheme:

supercritical CO under entrainer assistance₂A method of extracting oil from drilling waste, the method comprising the steps of:

s1, placing the drilling waste into a forced air drying box for drying, and then crushing by a crusher;

preferably, the drying temperature in S1 is 40-50 ℃, and the drying time is 12-24 hours.

Preferably, the drilling waste in the S1 is crushed by a crusher to increase the contact area, and the crushed drilling waste is crushed to 60-80 meshes.

S2, mixing the entrainer with the drilling waste obtained in the step S1, uniformly stirring, and putting into a supercritical extraction kettle;

the addition of the entrainer can change the density of the solvent to influence the solubility of the solute on one hand and change the molecular force between the solute and the entrainer to influence the solute on the supercritical CO on the other hand₂The solubility and the selectivity in the process are decisive, so that the entrainer is mixed with the drilling waste obtained in S1, the molecular acting force between the solute and the entrainer can be changed to the maximum extent, the release of extraction components is facilitated, and the mixture is filled into a supercritical extraction kettle after being uniformly stirred.

As a further improvement of the present invention, in order to further enhance the molecular interaction between the solute and the entrainer, the entrainer in S2 is preferably a mixture of one or both of methanol and ethanol. Further preferably, the concentration of the methanol solution is 99.9%, and the concentration of the ethanol solution is 99.5%.

Preferably, the entrainer is ethanol.

As a further improvement of the invention, the mass ratio of the entrainer to the drilling waste in S2 is 0-1: 9, not including 0.

Preferably, the stirring speed is 100 r/min-120 r/min. More preferably, the stirring time is 1-2 hours.

S3, performing supercritical carbon dioxide extraction on the mixture obtained in the step S2 to generate a solid product and a liquid mixture of drilling waste; the liquid mixture comprises carbon dioxide, an entrainer and oil;

preferably, the extraction temperature of the supercritical carbon dioxide extraction is 50 ℃.

Preferably, the extraction pressure of the supercritical carbon dioxide extraction is 14-20 MPa.

Preferably, the flow rate of the carbon dioxide extracted by the supercritical carbon dioxide is 30L/h, and the extraction time is 80 minutes.

S4, sequentially discharging the liquid mixture obtained in the S3 into a separation tank I and a separation tank II for separation, and separating oil;

at this time, CO₂The solute is separated from the gas phase after the solubility is reduced and the secondary separation is carried outA small amount of entrainer is volatilized and CO₂The gas can be recycled, and finally the solute oil is separated.

Preferably, the mixture is discharged into the separation tank I and the separation tank II in sequence by the circulation pump in S4.

As a further improvement of the invention, in order to further separate the solute and the entrainer, in S4, the pressure of the separation tank I is 8-10MPa, and the separation temperature is 50 ℃.

Further preferably, the pressure of the separation tank II is 6-8MPa, and the separation temperature is 30 ℃.

As a further improvement of the present invention, in S4, the solid product in the extraction tank is withdrawn after the carbon dioxide in the extraction tank is emptied.

And S5, after the extraction is finished, collecting the oil obtained in the S4 from the bottom of the separation tank.

As a general technical concept, the invention also provides an application of the entrainer-assisted supercritical carbon dioxide extraction method in removing pollutants in drilling waste.

The invention has the following characteristics and beneficial effects:

(1) the supercritical carbon dioxide extraction of the drilling waste under the assistance of the entrainer can effectively recover petroleum resources in the drilling waste, and simultaneously improves the polarity of the solvent, so that the heavy metal content in the drilling waste can be reduced, and the harm of the drilling waste to the environment is reduced.

(2) The process of the invention obviously increases the contact area between the supercritical carbon dioxide and the drilling waste by selecting a proper entrainer, reduces the operating pressure and temperature, reduces the energy consumption and greatly reduces the treatment cost. And the supercritical extraction process is optimized, so that the treatment efficiency is further improved, and the highest extraction rate can reach 92.20% under the optimal condition.

(3) The hydrocarbon substances in the oil extracted by the process are basically unchanged, and the supercritical carbon dioxide extraction process has less damage to the oil substances. The content of heavy metal and organic pollutants in the residual drilling waste is obviously reduced, and the harm of the drilling solid waste to soil and environment is reduced.

Drawings

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

FIG. 1 is a graph showing the comparison of S L0, the raw material of drilling waste in the present invention, and 6 heavy metal elements in the solid products (S L1, S L2, S L3, S L4, S L5) collected in examples 1 to 5.

FIG. 2 is a graph comparing the oil extraction and the residual oil yield (S L1, S L2, S L3, S L4, S L5) in examples 1 to 5 of the present invention.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The materials and equipment used in the following examples are commercially available. In the examples of the present invention, unless otherwise specified, the processes used were conventional processes, the equipment used were conventional equipment, and the data obtained below were average values of three or more tests.