Method for improving treatment effect of production wastewater of water-containing block of gas production layer

Abstract

The invention provides a method for improving the treatment effect of production wastewater in a water-containing block of a gas production layer, which comprises the following steps: adding an efficient defoaming agent according to 30-60% of the mass of a foam drainage agent to defoam produced water, and coating the surface of a filter of a treatment system with an oleophylic and hydrophobic material to remove oily substances in the produced water. Through combined application of the efficient defoaming agent and the oleophylic and hydrophobic material, the wastewater treatment effect can be improved, the effluent quality is optimized, and the service life of a gas field gathering and transportation and treatment system is prolonged. The defoaming agent has relatively strong chemical inertness, can react with other substances under the conditions that the pH is 2-12, the temperature is-15 DEG C to 70 DEG C and the water mineralization degree is not greater than 50000 mg / L, is wide in application range, and can meet wastewater treatment of all water quality characteristics of a current gas field; the oleophylic and hydrophobic material can be used for a long time and has good adsorption performance on oil substances, and the separation efficiency can reach 97% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field environmental protection, and in particular relates to a method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer. Background Art

[0002] As an important means of stabilizing the production of water-producing gas wells, foam drainage gas production has the advantages of simple operation and low cost and has been widely recognized. However, in gas production stations, the conventional defoaming agents used have the problem of insufficient defoaming. The discharged liquid contains a large amount of foam, which affects the separation effect of the separator and causes serious water accumulation in the gathering and transportation pipelines. At the same time, the unclean gas-liquid separation causes a large amount of high-mineralization formation water to enter the pipelines and dehydration devices, causing the pipelines and dehydration devices to be blocked and even corroded, affecting the normal operation of the gathering and dehydration equipment. In addition, the oily defoaming agent used for drainage gas production may affect the resource utilization of the treated water (such as the preparation of fracturing fluid, drilling fluid, etc.) and the groundwater environment after reinjection. Therefore, it is very necessary to close the loop and remove the additives.

[0003] The invention patent with patent number CN112587962A discloses a method for improving the treatment effect of gas field production wastewater. The method uses a high-efficiency defoamer compounded with polysiloxane-modified polyether, phosphate triester, silicone oil, hydroxyethyl cellulose, etc. for defoaming treatment. The average defoaming time of the defoamer is less than 13s, the average foam suppression height is less than 320mL, and the defoaming and foam suppression effects are good; the amount of defoamer used is small, which is about 45% of the amount of traditional defoamers; the use cost is about 40% of traditional defoamers. However, this method does not remove the oil in the produced water and cannot meet the requirements of wastewater treatment. Summary of the invention

[0004] The purpose of the present invention is to provide a method for improving the treatment effect of production wastewater in water-bearing blocks of gas-producing layers, thereby overcoming the above-mentioned technical problems existing in the prior art.

[0005] To this end, the technical solution provided by the present invention is as follows:

[0006] A method for improving the treatment effect of production wastewater in water-bearing blocks of gas-producing layers, wherein a high-efficiency defoaming agent is added according to 30%-60% of the mass of a foam drainage agent to defoam the produced water, and at the same time, an oleophilic and hydrophobic material is wrapped on the surface of a filter in the treatment system to remove oily substances in the produced water.

[0007] The mass of the foam drainage agent is calculated based on the daily water production, mass concentration and volume of produced water of the water-producing gas well.

[0008] The high-efficiency defoamer is composed of the following substances in percentage by mass: 7%-20% of polysiloxane-modified polyether, 3%-10% of phosphate triester, 0.5%-3% of silicone oil, 0.2%-1.5% of hydroxyethyl cellulose, and the rest is water.

[0009] The lipophilic and hydrophobic material is prepared by adding SiO 2 The nanoparticles are fully mixed and then soaked in cotton fabric, which is then dried. After repeating this process 3-5 times, the resulting fabric is laid flat on a soft metal mesh. 2 The mass of the nanoparticles is 3%-5% of the lipophilic and hydrophobic matrix solvent.

[0010] The polysiloxane-modified polyether is obtained by modifying allyl polyether with low-hydrogen silicone oil in the presence of a catalyst, and the mass percentage of hydrogen in the low-hydrogen silicone oil is not greater than 0.1%.

[0011] The preparation process of the polysiloxane-modified polyether is as follows: heating the allyl polyether and the vinyl double-capped catalyst to 50-60° C., then adding low-hydrogen silicone oil dropwise, and reacting at 65-75° C. for about 2-4 hours to obtain the product polysiloxane-modified polyether;

[0012] The amount of vinyl double-headed catalyst added per gram of allyl polyether is 20 μg, and the mass ratio of allyl polyether to low hydrogen silicone oil is 1.5:(1-1.5).

[0013] The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 50%-60%, and the mass percentages of the tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane are 35%-50%.

[0014] The mesh size of the metal wire mesh is 5mm*5mm-8mm*8mm.

[0015] The high-efficiency defoaming agent is added through an automatic dosing device installed between the wellhead gas tree and the gas gathering pipeline.

[0016] For daily water production less than 3m 3 For gas wells, 14 days is one filling cycle. The required high-efficiency defoamer is calculated based on the water production in one cycle and added once. For gas wells with daily water production of more than 3m 3 For gas wells, 7 days is one filling cycle. The required high-efficiency defoaming agent is calculated based on the water production in one cycle and added once.

[0017] The beneficial effects of the present invention are:

[0018] The invention can improve the wastewater treatment effect, optimize the effluent water quality and prolong the service life of the gas field gathering, transportation and treatment system through the combined application of the high-efficiency defoaming agent and the lipophilic and hydrophobic material.

[0019] The high-efficiency defoamer of the present invention is non-toxic, pollution-free, and environmentally friendly; it has strong chemical inertness, does not react with other substances under the conditions of pH of 2-12, temperature of -15°C-70°C, and water mineralization not greater than 50000 mg / L, has a wide range of applications, and can meet the requirements of wastewater treatment with all water quality characteristics of current gas fields; the average defoaming time of the defoamer is less than 13 seconds, and the average foam suppression height is less than 320 ml; the amount of the defoamer used is about 45% of the amount of the traditional defoamer used; and the use cost is about 40% of that of the traditional defoamer.

[0020] The oleophilic and hydrophobic material of the present invention can be used for a long time, and the separation efficiency can reach more than 97%. The fabric still has a good separation effect after being reused 30 times, has good adsorption performance for oil substances, and can be used as a filter medium in an oil-water separation system. The adsorbed oil is removed through the backwashing system of the produced water treatment system itself, so that the medium can be reused. DETAILED DESCRIPTION

[0021] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] Now, exemplary embodiments of the present invention are introduced. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments are not intended to limit the present invention.

[0023] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0024] Example 1

[0025] This embodiment provides a method for improving the treatment effect of production wastewater in the water-bearing block of the gas-producing layer, wherein a high-efficiency defoaming agent is added according to 30%-60% of the mass of the foam drainage agent to defoam the produced water, and at the same time, an oleophilic and hydrophobic material is wrapped on the filter surface of the treatment system to remove oily substances in the produced water.

[0026] The mass of the foam drainage agent is calculated based on the daily water production, mass concentration and volume of produced water of the water-producing gas well.

[0027] The invention can improve the wastewater treatment effect, optimize the effluent water quality and prolong the service life of the gas field gathering, transportation and treatment system through the combined application of the high-efficiency defoaming agent and the lipophilic and hydrophobic material.

[0028] Example 2

[0029] Based on Example 1, this example provides a method for improving the treatment effect of production wastewater in the water-containing block of the gas-producing layer, wherein the high-efficiency defoaming agent is composed of the following substances in percentage by mass: polysiloxane-modified polyether 7%-20%, phosphate triester 3%-10%, silicone oil 0.5%-3%, hydroxyethyl cellulose 0.2%-1.5%, and the rest is water.

[0030] The principle of this high-efficiency defoamer:

[0031] Polysiloxane modified polyether is used to control the generation and stability of bubbles in liquids. It can effectively inhibit the formation of bubbles on the liquid surface and prevent the bubbles from persisting and spreading in the liquid. Triphosphate can quickly destroy the foam in the liquid, reduce the surface tension, and reduce or prevent the formation of foam. Silicone oil is stable in nature and can quickly diffuse to the surface of bubbles in the liquid, reduce the surface tension of the foam, and thus cause the foam to burst and release gas. Hydroxyethyl cellulose is used as a thickener to increase viscosity and delay the process of the defoamer forming larger particles.

[0032] The lipophilic and hydrophobic material is prepared by adding SiO 2 The nanoparticles are fully mixed and then soaked in cotton fabric, which is then dried. After repeating this process 3-5 times, the resulting fabric is laid flat on a soft metal mesh. 2 The mass of the nanoparticles is 3%-5% of the lipophilic and hydrophobic matrix solvent.

[0033] The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 50%-60%, and the mass percentages of the tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane are 35%-50%.

[0034] Principle of oleophilic and hydrophobic materials:

[0035] After being soaked in an oleophilic and hydrophobic matrix solvent, cotton fabric can absorb oily substances in the produced water. 2 The addition of nanoparticles can improve water purification effects.

[0036] Example 3

[0037] Based on Example 2, this example provides a method for improving the treatment effect of production wastewater in the water-containing block of the gas-producing layer, wherein the high-efficiency defoaming agent is composed of the following substances in percentage by mass: 7% polysiloxane-modified polyether, 10% phosphate triester, 3% silicone oil, 1.0% hydroxyethyl cellulose, and the rest is water.

[0038] Preparation process of high-efficiency defoaming agent: add the formulated amount of polysiloxane-modified polyether and triester of phosphate to the formulated amount of water while stirring, stir evenly, add the formulated amount of silicone oil and hydroxyethyl cellulose in sequence, and stir for 3 minutes to obtain the defoaming agent.

[0039] The lipophilic and hydrophobic material is prepared by adding SiO 2 The nanoparticles are fully mixed and then soaked in cotton fabric, which is then dried. After repeating this process for 5 times, the resulting fabric is laid flat on a soft metal mesh. 2 The mass of the nanoparticles is 5% of the lipophilic and hydrophobic matrix solvent.

[0040] The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 50%, the mass percentage of the tetraethylsilane and the 1,1,1,3,3,3-hexamethyldisilazane is 50%, and the mass ratio of the two is 1:4.

[0041] The preparation process of polysiloxane-modified polyether is as follows: allyl polyether and vinyl double-capped catalyst are heated to 50-60°C, low hydrogen silicone oil is added dropwise, and the reaction is carried out at 65-75°C for about 2-4 hours to obtain the product polysiloxane-modified polyether;

[0042] The amount of vinyl double-capped catalyst added per gram of allyl polyether is 20 μg, the mass ratio of allyl polyether to low hydrogen silicone oil is 1.5:(1-1.5), and the mass percentage of hydrogen in the low hydrogen silicone oil is not more than 0.1%.

[0043] Example 4

[0044] Based on Example 2, this example provides a method for improving the treatment effect of production wastewater in the water-containing block of the gas-producing layer, wherein the high-efficiency defoaming agent is composed of the following substances in percentage by mass: 14% polysiloxane-modified polyether, 6% phosphate triester, 0.5% silicone oil, 0.2% hydroxyethyl cellulose, and the rest is water.

[0045] The preparation process of the high-efficiency defoamer is shown in Example 3.

[0046] The lipophilic and hydrophobic material is prepared by adding SiO 2The nanoparticles are fully mixed and then soaked in cotton fabric, which is then dried. After repeating this process three times, the resulting fabric is laid flat on a soft metal mesh. 2 The mass of the nanoparticles is 4% of the lipophilic and hydrophobic matrix solvent.

[0047] The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 60%, the mass percentage of the tetraethylsilane and the 1,1,1,3,3,3-hexamethyldisilazane is 40%, and the mass ratio of the two is 3:1.

[0048] The preparation process of polysiloxane-modified polyether is shown in Example 3.

[0049] Example 5

[0050] Based on Example 2, this example provides a method for improving the treatment effect of production wastewater in the water-containing block of the gas-producing layer, wherein the high-efficiency defoaming agent is composed of the following substances in percentage by mass: 20% polysiloxane-modified polyether, 3% phosphate triester, 1.8% silicone oil, 1.5% hydroxyethyl cellulose, and the rest is water.

[0051] The preparation process of the high-efficiency defoamer is shown in Example 3.

[0052] The lipophilic and hydrophobic material is prepared by adding SiO 2 The nanoparticles are fully mixed and then soaked in cotton fabric, which is then dried. After repeating this process three times, the resulting fabric is laid flat on a soft metal mesh. 2 The mass of the nanoparticles is 3% of the lipophilic and hydrophobic matrix solvent.

[0053] The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 55%, the mass percentage of the tetraethylsilane and the 1,1,1,3,3,3-hexamethyldisilazane is 45%, and the mass ratio of the two is 1:1.

[0054] The preparation process of polysiloxane-modified polyether is shown in Example 3.

[0055] Defoamer comparison ratio:

[0056] Take 30 parts of 5000cps dimethyl silicone oil and 3 parts of hydrophobic white carbon black and reflux for reaction at 120°C for 3 hours to obtain a white viscous modified silicone paste; mix 5 parts of 1000cps hydrogenated silicone oil with the modified silicone paste and shear disperse at 5000r / min for 30 minutes, add 8 parts of sorbitan fatty acid ester and sorbitan monooleate polyoxyethylene ether, and shear disperse at 5000r / min for 15 minutes; slowly add 120 parts of deionized water, shear disperse at 8000r / min for 60 minutes, and finally add 0.1 parts of KH550, 0.2 parts of hydroxypropyl cellulose and 0.2 parts of sodium benzoate, and shear disperse evenly at 2000r / min to obtain.

[0057] The following performance tests were performed on the comparative example defoamer and the high-efficiency defoamers prepared in Examples 3 to 5:

[0058] 1. Test of defoaming performance

[0059] At room temperature, pour 25mL of 2wt% sodium dodecylbenzene sulfonate aqueous solution into a 100mL measuring cylinder, shake it up and down several times to make the foaming liquid reach 100mL. Add 0.1wt% defoamer to the foaming liquid, and start the stopwatch until the foam disappears completely. The shorter the time, the better the defoaming performance of the defoamer. Repeat the experiment three times and take the average value.

[0060] 2. Test of anti-foaming performance

[0061] At room temperature, add 100mL of 2wt% sodium dodecylbenzene sulfonate aqueous solution as foaming liquid in a 1L measuring cylinder, and add 0.1wt% defoamer to the foaming liquid. Pass nitrogen into the foaming liquid and record the time when the foam reaches the 300mL mark. The longer the time, the better the anti-foaming performance. Repeat the experiment three times and take the average value.

[0062] 3. Test of water dispersion performance

[0063] Take 0.5g of defoamer and add it to 100mL of water. Stir well and observe the dispersion of the defoamer in water. If there is no stratification or floating oil, it proves that the performance of the defoamer is good.

[0064] 4. Test of acid and alkali resistance

[0065] Take 0.5g of defoamer and add it to 100mL of hydrochloric acid solution with pH=2 and 100mL of sodium hydroxide solution with pH=12 respectively, and observe the acid and alkali resistance of the defoamer. If there is no floating oil, it proves that the acid and alkali resistance is good.

[0066] 5. Test of high temperature resistance

[0067] Take 0.5g of defoamer and add it to 100mL of water, let it stand at 60℃, and observe the high temperature resistance of the defoamer. If there is no floating oil, it proves that the high temperature resistance is good.

[0068] 6. Centrifugal stability test

[0069] Take 0.5g of defoamer and add it to 100mL of water, stir evenly, centrifuge at 3000r / min for 5min, and observe the centrifugal stability of the defoamer. If there is no stratification, it proves that the centrifugal stability is good.

[0070] The test results are shown in Table 1.

[0071] Table 1 Defoamer test performance

[0072] Defoaming agent Defoaming time / s Anti-foam time / s Water dispersibility Acid and alkali resistance High temperature resistance Centrifugal stability Example 3 8.9 31.4 Unbleached Oil Unbleached Oil Unbleached Oil Unstratified Example 4 13.2 38.9 Unbleached Oil Unbleached Oil Unbleached Oil Unstratified Example 5 15.3 44.6 Unbleached Oil Unbleached Oil Unbleached Oil Unstratified Comparative Example 21.2 20.5 Unbleached Oil Floating oil Floating oil Unstratified

[0073] As can be seen from Table 1, the high-efficiency defoamer of the present invention is non-toxic, pollution-free, and environmentally friendly; it has strong chemical inertness, does not react with other substances under the conditions of pH 2-12, temperature -15°C-70°C, and water mineralization not greater than 50000 mg / L, has a wide range of applications, and can meet the wastewater treatment of all water quality characteristics of the current gas field; the average defoaming time of the defoamer is less than 13s.

[0074] For daily water production less than 3m 3 For gas wells, 14 days is one filling cycle. The required high-efficiency defoamer is calculated based on the water production in one cycle and added once. For gas wells with daily water production of more than 3m 3 For gas wells, 7 days is one filling cycle. The required high-efficiency defoaming agent is calculated based on the water production in one cycle and added once.

[0075] The oleophilic and hydrophobic material of the present invention can be used for a long time, and the separation efficiency can reach more than 97%. The fabric still has a good separation effect after being reused 30 times, has good adsorption performance for oil substances, and can be used as a filter medium in an oil-water separation system. The adsorbed oil is removed through the backwashing system of the produced water treatment system itself, so that the medium can be reused.

[0076] The oleophilic and hydrophobic materials prepared in Examples 3-5 were wrapped on the filter surface and operated simultaneously with the produced water treatment system. When the fabric was found to be damaged or the oil removal rate was lower than 90% during operation and maintenance, it was replaced. Finally, the oil content of the effluent was ensured to be stable below 18 mg / L.

[0077] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer, characterized in that: High-efficiency defoaming agent is added at 30%-60% of the mass of the foam drainage agent to defoam the produced water, and at the same time, oleophilic and hydrophobic materials are wrapped on the surface of the filter of the treatment system to remove oily substances in the produced water.

2. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to claim 1, characterized in that: The mass of the foam drainage agent is calculated based on the daily water production, mass concentration and volume of produced water of the water-producing gas well.

3. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to claim 1, characterized in that: The high-efficiency defoamer is composed of the following substances in percentage by mass: 7%-20% of polysiloxane-modified polyether, 3%-10% of phosphate triester, 0.5%-3% of silicone oil, 0.2%-1.5% of hydroxyethyl cellulose, and the rest is water.

4. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to claim 1, characterized in that: The oleophilic and hydrophobic material is prepared by adding SiO2 nanoparticles to an oleophilic and hydrophobic matrix solvent, fully mixing the mixture, soaking cotton fabric in the mixture, air-drying the mixture, repeating the process 3-5 times, and then laying the resulting fabric flat on a soft metal mesh; wherein the mass of the SiO2 nanoparticles is 3%-5% of the oleophilic and hydrophobic matrix solvent.

5. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to claim 3, characterized in that: The polysiloxane-modified polyether is obtained by modifying allyl polyether with low-hydrogen silicone oil in the presence of a catalyst, and the mass percentage of hydrogen in the low-hydrogen silicone oil is not greater than 0.1%.

6. A method for improving the treatment effect of production wastewater in a water-bearing area of ​​a gas-producing layer according to claim 3, characterized in that: The preparation process of the polysiloxane-modified polyether is as follows: heating the allyl polyether and the vinyl double-capped catalyst to 50-60° C., then adding low-hydrogen silicone oil dropwise, and reacting at 65-75° C. for about 2-4 hours to obtain the product polysiloxane-modified polyether; The amount of vinyl double-headed catalyst added per gram of allyl polyether is 20 μg, and the mass ratio of allyl polyether to low hydrogen silicone oil is 1.5:(1-1.5).

7. A method for improving the treatment effect of production wastewater in a water-bearing zone of a gas-producing layer according to claim 4, characterized in that: The lipophilic and hydrophobic matrix solvent is obtained by mixing polydimethyloxane, tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane, wherein the mass ratio of the polydimethyloxane is 50%-60%, and the mass percentages of the tetraethylsilane and 1,1,1,3,3,3-hexamethyldisilazane are 35%-50%.

8. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to claim 4, characterized in that: The mesh size of the metal wire mesh is 5mm*5mm-8mm*8mm.

9. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to any one of claims 1 to 8, characterized in that: The high-efficiency defoaming agent is added through an automatic dosing device installed between the wellhead gas tree and the gas gathering pipeline.

10. A method for improving the treatment effect of production wastewater in a water-bearing block of a gas-producing layer according to any one of claims 1 to 8, characterized in that: For daily water production less than 3m 3 For gas wells, 14 days is one filling cycle. The required high-efficiency defoamer is calculated based on the water production in one cycle and added once. For gas wells with daily water production of more than 3m 3 For gas wells, 7 days is one filling cycle. The required high-efficiency defoaming agent is calculated based on the water production in one cycle and added once.