Method for carrying out sienna treatment on sewage produced by oil field and improving recovery efficiency

Abstract

The invention discloses a method for generating and receiving treatment of oilfield output sewage and for improving the recovery ratio, the oilfield output sewage is complex in pollutant and large in volume, and the method can well realize large-scale cyclic utilization of the output sewage and relieve the standard discharge pressure. Meanwhile, yield increase and crude oil recovery efficiency can be achieved, and the stable yield increase pressure of an oil field is relieved. The sienna material is not dissolved in crude oil, the oil quality is not affected in the exploitation process, and due to the addition of the sienna material, the separation speed of produced water and crude oil can be increased.

Description

(1) Technical field

[0001] The invention relates to a method for treating oilfield produced sewage and using the method for improving recovery rate. (2) Background technology

[0002] Most oil wells in my country have entered the late stages of tertiary oil recovery (TERR), resulting in high water content in the produced fluid. Oilfield wastewater is massive and complex, often containing harmful substances such as petroleum hydrocarbons, bacteria, polymers, and suspended solids. The composition of produced wastewater varies from one oilfield to another, making treatment challenging. Currently, some oilfield wastewater is treated to meet discharge standards, but this is subject to high costs and limited treatment capacity. Other wastewater is treated with physical, chemical, or biological methods for reinjection, but this can result in incomplete oil removal, negatively impacting water quality or causing secondary environmental pollution, as well as lengthy and costly treatment times.

[0003] Therefore, it is of great significance to explore an efficient treatment method and process for oilfield produced wastewater.

[0004] Bio-based nanomaterials have promising applications in the oil industry due to their excellent biocompatibility, unique molecular structure, insolubility in crude oil, and the ability to deform the oil-water interface upon reaching it. While these materials significantly enhance oil recovery, their application in treating oilfield wastewater has not been reported. (3) Summary of the invention

[0005] The purpose of the present invention is to provide a method for treating oilfield produced wastewater and using it to improve oil recovery. The method can effectively treat oilfield produced wastewater and improve crude oil recovery to achieve increased crude oil production. It is simple to implement and easy to scale up, providing a new path for the resource utilization of oilfield produced wastewater.

[0006] The technical solution adopted in the present invention is:

[0007] The present invention provides a method for treating oilfield produced wastewater and using it to improve oil recovery, the method comprising:

[0008] (1) Add the bio-based raw nanomaterial C series to the oilfield wastewater, stir evenly and then let it stand to separate into layers to obtain an upper oil phase, a middle water phase and a lower solid phase;

[0009] (2) taking the middle layer aqueous phase and mixing it evenly with the bio-based nanomaterial series A to obtain a mixed solution;

[0010] (3) Crude oil is pumped into the porous medium from the injection end until the crude oil is pumped out from the production end and the injection is stopped. Water is then pumped in to displace the crude oil until the production end no longer produces oil. At this point, the water production rate of the porous medium is 100%, and the porous medium is obtained in a residual oil state.

[0011] (4) injecting the mixed solution of step (2) into the porous medium in the residual oil state of step (3); after the injection of the mixed solution is completed, injecting water to displace the crude oil; collecting all the outflowing liquid from the output end; standing for oil and water separation; collecting the oil phase and the water phase; and reusing the water phase to displace the crude oil, thereby achieving efficient treatment of oilfield produced wastewater and improving crude oil recovery.

[0012] Furthermore, the bio-based nanomaterial C series in step (1) includes BioNanoEM-C (purchased from Hangzhou Shengnan Bioengineering Co., Ltd.), and the amount of the bio-based nanomaterial C series added to the oilfield produced wastewater is 10 to 100 g / L, preferably 10 g / L.

[0013] Furthermore, step (1) is allowed to stand for 10-30 minutes for stratification.

[0014] Furthermore, the bio-based nanomaterial series A in step (2) includes BioNanoEM-A (purchased from Hangzhou Shengnan Bioengineering Co., Ltd.), and the amount of the bio-based nanomaterial series A added to the aqueous phase is 1 to 100 g / L, preferably 100 g / L.

[0015] Furthermore, the porosity of the porous medium in step (3) is 15-50%, and the permeability is 2.5-35000 mD.

[0016] Furthermore, in step (4), the flow rate of the mixed solution injected into the porous medium is 0.2 to 0.5 mL / min, the injection volume of the mixed solution is 3 to 24 times (preferably 13 times) the total pore volume of the porous medium, and the injection volume of water is 1 to 3 times (preferably 1 times) the total pore volume of the porous medium.

[0017] The present invention adds the bio-based raw nanomaterial C series to oilfield wastewater, stirs it evenly, and then allows it to stand. Under the action of the raw nanomaterial C series, the oil droplets in the oily wastewater are enriched and separated. The lower solid phase is filtered out, and the intermediate aqueous phase is taken and evenly mixed with the bio-based raw nanomaterial A series. The mixed solution is then injected into a porous medium. Due to the unique spatial conformation and inherent positive and negative potential of the raw nanomaterial A series, it can interact dynamically with crude oil components at the microscopic level, driving crude oil to seep through the pores within the porous medium, achieving the goals of increasing crude oil production and treating wastewater. Oilfield wastewater has a complex composition, some of which are oleophilic substances that are compatible with crude oil. Combining this with the raw nanomaterial can better achieve increased crude oil production and improved oil recovery, while also effectively treating oilfield wastewater.

[0018] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0019] Oilfield wastewater contains complex pollutants and is large in volume. The method of the present invention effectively achieves large-scale recycling of produced wastewater, alleviating the pressure to meet discharge standards. It also improves crude oil recovery, increasing production and alleviating the pressure on oilfields to maintain stable and increased production. The bio-based materials used in the present invention are insoluble in crude oil and do not affect oil quality during the extraction process. The addition of the bio-based materials also accelerates the separation of produced water from crude oil. (IV) Specific implementation methods

[0020] The present invention is further described below with reference to specific embodiments, but the protection scope of the present invention is not limited thereto:

[0021] The bio-based biomaterials BioNanoEM-C1 and BioNanoEM-A4 used in the examples of the present invention were purchased from Hangzhou Shengnan Bioengineering Co., Ltd. Other serial numbers of BioNanoEM-C series or BioNanoEM-A series are also applicable to the present invention. The following examples only represent part of the verification experiments.

[0022] Example 1

[0023] (1) Take 200 mL of oilfield wastewater and measure the COD to be 15580 mg·L -1 , ammonia nitrogen is 26 mg·L -1 , suspended matter 64mg·L -1 , add 20g of BioNanoEM-C1, stir evenly at room temperature (25-30℃) and let it stand for 30min, filter to remove the upper oil phase and the lower solid phase, and retain the middle water phase.

[0024] (2) Mix 2.5 g of BioNanoEM-A4 with 200 mL of the aqueous phase obtained in step (1), and stir evenly to obtain a mixed solution.

[0025] (3) Pretreatment of porous media: Take a porous medium and measure its porosity to be 47%, permeability to be 12989mD, and pore volume to be 9.5mL. One end of the porous medium is the injection end and the other end is the production end. Crude oil is injected into the porous medium from the injection end until the production end discharges crude oil and injection stops. Water is then injected from the injection end to displace the crude oil until the water production rate reaches 100%. The porous medium is then measured to have a residual oil saturation of 37.8%, a water saturation of 62.2%, and a water drive recovery rate of 30%.

[0026] (4) The mixed solution prepared in step (2) was stirred at 0.5 mL min -1In step (3), the flow rate injection is carried out into the porous medium in the residual oil state, and the total injection volume is 24 times the pore volume of the porous medium. After the injection of the mixed solution is completed, water of 1.5 times the pore volume of the porous medium is injected. All the outflowing liquid is collected from the production end, and the oil and water are allowed to stand for separation, and the oil phase is collected. The total oil phase recovery factor is measured to be 67%, and the recovery factor is increased by 37%. The water phase can be repeatedly reinjected.

[0027] Example 2

[0028] (1) Take 200 mL of oilfield wastewater and measure the COD to be 662 mg·L -1 , ammonia nitrogen is 10 mg·L -1 , suspended matter 181 mg·L -1 , add 2 g of BioNanoEM-C1, stir evenly at room temperature and let it stand for 10 minutes, remove the upper oil phase and the lower solid phase, and retain the middle water phase.

[0029] (2) Mix 20 g of BioNanoEM-A4 with 200 mL of the aqueous phase from step (1) to obtain a mixed solution.

[0030] (3) Take a porous medium with a porosity of 43%, a permeability of 7525 mD, and a pore volume of 8.5 mL. Crude oil is injected into the porous medium from the injection end until the crude oil is discharged from the production end and injection is stopped. Water is then injected from the injection end to displace the crude oil until the water production rate reaches 100%. The porous medium is then left in a residual oil state with a residual oil saturation of 39.9%, a water saturation of 60.1%, and a water drive recovery of 51%.

[0031] (4) The mixed solution prepared in step (2) was stirred at 0.5 mL min -1 In step (3), the flow rate injection is carried out in the porous medium in the residual oil state, and the total injection volume is 13 times the pore volume of the porous medium. After the injection of the mixed liquid is completed, pure water of 1 times the pore volume of the porous medium is injected. All the outflowing liquid is collected from the production end, and the oil and water are allowed to stand for separation, and the oil phase is recovered. The total oil phase recovery rate is measured to be 97%, and the recovery rate is increased by 46%. The water phase can be repeatedly reinjected.

[0032] Example 3

[0033] (1) Take 200 mL of oilfield wastewater and measure the COD to be 17005 mg·L -1 , ammonia nitrogen is 14 mg·L -1 , suspended matter 124 mg·L -1 , add 10g of BioNanoEM-C1, stir evenly at room temperature and let it stand for 15 minutes, remove the upper oil phase and the lower solid phase, and retain the middle water phase.

[0034] (2) 10 g of BioNanoEM-A4 was mixed evenly with 200 mL of the aqueous phase from step (1) to obtain a mixed solution.

[0035] (3) Take a porous medium with a porosity of 46%, a permeability of 30965 mD, and a pore volume of 9.8 mL. Crude oil is injected into the porous medium from the injection end until crude oil is discharged from the outlet end and injection is stopped. Water is injected from the injection end to displace the crude oil until the water production rate reaches 100%. The porous medium is then left in a residual oil state with a residual oil saturation of 38.1%, a water saturation of 61.9%, and a water drive recovery of 49%.

[0036] (4) The mixed solution prepared in step (2) was stirred at 0.2 mL min -1 In step (3), the flow rate injection is carried out in the porous medium in the residual oil state, and the total injection volume is 5 times the pore volume of the porous medium. After the injection of the mixed liquid is completed, pure water 3 times the pore volume of the porous medium is injected. All the outflowing liquid is collected from the production end, and the oil and water are separated and the oil phase is recovered. The total oil phase recovery rate is measured to be 71%, and the recovery rate is increased by 22%. The water phase can be repeatedly reinjected.

[0037] Example 4

[0038] (1) Take 200 mL of oilfield wastewater and measure the COD to be 170 mg·L -1 , ammonia nitrogen is 11 mg·L -1 , suspended matter 7mg·L -1 , add 2 g of BioNanoEM-C1, stir evenly at room temperature and let it stand for 10 minutes, remove the upper oil phase and the lower solid phase, and retain the middle water phase.

[0039] (2) 0.2 g of BioNanoEM-A4 was mixed uniformly with 200 mL of the aqueous phase from step (1) at a mass ratio of 0.1% to obtain a mixed solution.

[0040] (3) Take a porous medium with a porosity of 15.7%, a permeability of 2.5 mD, and a pore volume of 3.6 mL. Crude oil is injected into the porous medium from the injection end until crude oil is discharged from the outlet end and injection is stopped. Water is then injected from the injection end to displace the crude oil until the water production rate reaches 100%. The porous medium is then left in a residual oil state with a residual oil saturation of 38.1%, a water saturation of 61.9%, and a water drive recovery of 32%.

[0041] (4) The mixed solution prepared in step (2) was stirred at 0.2 mL min -1In step (3), the flow rate injection is carried out in the porous medium under the residual oil state, and the total injection volume is 3 times the pore volume of the porous medium. After the injection of the mixed liquid is completed, pure water with a volume of 1 times the pore volume of the porous medium is injected. All the outflowing liquid is collected from the production end, and the oil and water are separated and the oil phase is recovered. The total oil phase recovery rate is measured to be 44%, and the recovery rate is increased by 12%. The water phase can be repeatedly reinjected.

[0042] The contents described in this specification are merely an enumeration of implementation forms of the inventive concept, and the protection scope of the present invention should not be considered as being limited to the specific forms described in the embodiments.

Claims

1. A method for treating oilfield wastewater and improving oil recovery, characterized in that: The method comprises: (1) Add the bio-based raw nanomaterial C series to the oilfield wastewater, stir it evenly, and then let it stand to separate into layers to obtain an upper oil phase, a middle water phase, and a lower solid phase; (2) taking the middle layer aqueous phase and mixing it evenly with the bio-based nanomaterial series A to obtain a mixed solution; (3) Crude oil is first pumped into the porous medium from the injection end until the crude oil is pumped out from the production end and the injection is stopped. Then water is pumped in to displace the crude oil until the production end no longer produces oil. At this time, the water production rate of the porous medium is 100%, and the porous medium is obtained in a residual oil state; (4) injecting the mixed solution of step (2) into the porous medium in the residual oil state of step (3); after the injection of the mixed solution is completed, injecting water to displace the crude oil; collecting all the outflowing liquid from the output end; standing for oil and water separation; collecting the oil phase and the water phase; and reusing the water phase to displace the crude oil, thereby achieving efficient treatment of oilfield produced wastewater and improving crude oil recovery.

2. The method according to claim 1, wherein The amount of the bio-based nanomaterial C series added to the oilfield produced wastewater in step (1) is 10 to 100 g / L.

3. The method according to claim 1, wherein Step (1) is to stand and separate for 10-30 minutes.

4. The method according to claim 1, wherein In step (2), the amount of the bio-based nanomaterial series A added to the aqueous phase is 1 to 100 g / L.

5. The method according to claim 1, wherein The porosity of the porous medium in step (3) is 15-50%, and the permeability is 2.5-35000 mD.

6. The method according to claim 1, wherein In step (4), the flow rate of the mixed solution injected into the porous medium is 0.2-0.5 mL / min, the injection volume of the mixed solution is 3-24 times the total pore volume of the porous medium, and the injection volume of water is 1-3 times the total pore volume of the porous medium.