Method and system for extracting deuterium and lithium from oil and gas field produced water

Abstract

The invention belongs to the field of associated mineral extraction methods, and discloses a method and system for extracting deuterium and lithium from oil and gas field produced water. The method comprises the following steps: sequentially carrying out oil removal treatment, desulfurization treatment, adsorption pretreatment, lithium ion adsorption, divalent cation removal, first-time electrolysis, filtration and purification, Na2CO3 feeding, evaporation and condensation, second-time electrolysis and third-time electrolysis on the oil and gas field produced water, and simultaneously extracting deuterium and lithium in the oil and gas field produced water. On the basis of meeting the lithium extraction requirement of'pretreatment + adsorption + membrane separation + crystallization ', a water electrolysis process is added, deuterium and lithium are synchronously extracted, and through system optimization, the product purity and the recovery rate are improved, and the energy consumption is reduced.

Description

Technical Field

[0001] The present application belongs to the field of associated mineral extraction methods, and in particular relates to a method and system for extracting deuterium and lithium from produced water in oil and gas fields. Background Art

[0002] Oil and gas field produced water, with its massive volume, complex composition, and high treatment costs, has long plagued oil and gas field production companies. Lithium, known as "white oil," is a key element required for strategic emerging and future industries such as electrochemical energy storage and nuclear fusion. Global lithium production increased fivefold from 2010 to 2022. Natural water contains 145-155 ppm of deuterium. Heavy water (D2O) is a fundamental material for nuclear energy development. Because heavy water has a slightly different boiling point from ordinary water, it can be purified by distillation. Heavy water has a slower electrolysis rate than ordinary water, allowing it to be extracted by electrolysis. Approximately half of the produced water from wellheads in the Southwest Oil and Gas Fields, the Qaidam Basin, the Tarim Basin, and the Jianghan Basin contains lithium ions at concentrations between 6 and 300 mg / L, making it of significant economic value.

[0003] Therefore, it is necessary to provide a method and system for extracting deuterium and lithium from produced water in oil and gas fields. On the basis of meeting the reinjection requirements, the system couples membrane separation, adsorption, electrolysis and other processes to maximize the needs of green electricity consumption and deuterium and lithium extraction, realize the resource utilization of associated minerals in oil and gas field water, and turn waste into treasure. Summary of the Invention

[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of this application is to provide a method and system for extracting deuterium and lithium from oil and gas field produced water. On the basis of "pretreatment + adsorption + membrane separation + crystallization" that meets the requirements for lithium extraction, an electrolysis water process is added to simultaneously extract deuterium and lithium from oil and gas field produced water, thereby improving product purity and recovery rate and reducing energy consumption.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A method for extracting lithium deuterium from produced water in oil and gas fields, comprising:

[0007] Deoiling the produced water from oil and gas fields to obtain deoiled wastewater;

[0008] Desulfurizing the deoiled wastewater to obtain desulfurized wastewater;

[0009] Adsorption pretreatment is performed on the desulfurization wastewater to obtain a pretreatment liquid that removes suspended matter and trace oil droplets;

[0010] Adsorbing lithium ions on the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution;

[0011] Removing divalent cations from the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution;

[0012] Performing a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2;

[0013] Filtering and purifying the concentrated stock solution to obtain a filtrate;

[0014] Adding Na2CO3 into the filtrate and performing precipitation separation to obtain lithium carbonate and mother liquor;

[0015] The mother liquor is evaporated and condensed to obtain NaCl solid and condensed crude heavy water;

[0016] The condensed crude heavy water is subjected to a second electrolysis to obtain heavy water, H2 and O2 as products;

[0017] The product heavy water is electrolyzed for a third time to obtain deuterium gas and O2.

[0018] Furthermore, before desulfurization treatment of the deoiled wastewater, the following steps are included:

[0019] Adjust the pH of degreasing wastewater.

[0020] Furthermore, the deoiled wastewater is subjected to desulfurization treatment, including:

[0021] The hydrogen sulfide gas is blown off from the degreasing wastewater by air and then absorbed by NaOH.

[0022] Furthermore, the pretreatment liquid is subjected to lithium ion adsorption, including:

[0023] The lithium ions in the pretreatment solution are adsorbed by a manganese-based ion sieving adsorbent.

[0024] Furthermore, the produced water from the oil and gas fields meets the following conditions: 5≤pH≤8, total organic carbon content≤100mg / L, suspended solids content≤100mg / L, 6mg / L≤Li + Concentration ≤ 300 mg / L, 80 mg / L ≤ S 2- Concentration ≤300mg / L.

[0025] On the other hand, the present application discloses a system for extracting deuterium and lithium from produced water in oil and gas fields, comprising:

[0026] Air flotation device, used to remove oil from produced water of oil and gas fields to obtain deoiled wastewater;

[0027] The stripping device is used to desulfurize the deoiled wastewater to obtain desulfurized wastewater;

[0028] Adsorption pretreatment device, used for adsorption pretreatment of desulfurization wastewater to obtain pretreated liquid that removes suspended matter and trace oil droplets;

[0029] A lithium ion adsorption device is used to adsorb lithium ions from the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution;

[0030] A nanofiltration device is used to remove divalent cations from the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution;

[0031] A first electrolysis device is used to perform a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2;

[0032] A filtration and purification device is used to filter and purify the concentrated raw liquid to obtain a filtrate;

[0033] An evaporation crystallization device is used to add Na2CO3 to the filtrate and perform precipitation separation to obtain lithium carbonate and mother liquor; the mother liquor is evaporated and condensed to obtain NaCl solid and condensed crude heavy water;

[0034] The second electrolysis device is used to perform a second electrolysis on the condensed crude heavy water to obtain heavy water, H2 and O2 as products;

[0035] The third electrolysis device is used to perform a third electrolysis on the product heavy water to obtain deuterium gas and O2.

[0036] Furthermore, the adsorption pretreatment device includes a flocculation sedimentation unit, a sand-carbon filtration unit and an ultrafiltration unit connected in sequence, which are used to perform multi-precision filtration on suspended matter and trace oil droplets in the desulfurization wastewater.

[0037] Furthermore, the lithium-poor water is used to backwash the ultrafiltration unit and the filtration purification device or as reinjection water;

[0038] The backwash drainage of the ultrafiltration unit and the filtration purification device is discharged as reinjection water;

[0039] The impurity solution is discharged as reinjection water.

[0040] Furthermore, the reinjection water meets the following conditions: pH = 7, total organic carbon content ≤ 100 mg / L, suspended solids content ≤ 1 mg / L, S 2- Concentration ≤5mg / L.

[0041] Furthermore, the lithium ion adsorption device includes a plurality of adsorption towers filled with manganese-based ion sieving adsorbents, which are used for adsorbing and desorbing lithium ions respectively.

[0042] The technical effects and advantages of this application are:

[0043] 1. The method of the present application makes full use of membrane separation, adsorption and other processes to carry out the cascade concentration and purification of important mineral lithium, which can reduce the processing volume and scale of subsequent electrolysis and evaporation equipment, and is highly efficient and energy-saving.

[0044] 2. The water electrolysis process of the present application can absorb surplus renewable electricity such as photovoltaic, wind power, and nuclear power to produce low-cost green hydrogen, and can also increase the concentration of deuterium and lithium in the solution, achieving multiple goals at one stroke.

[0045] 3. This application integrates oil and gas field wastewater treatment, heavy water preparation, and lithium carbonate preparation to meet the needs of green environmental protection and associated mineral recovery in oil and gas fields.

[0046] 4. This application has a wide adaptability to water quality and is suitable for produced water from oil and gas fields with high salt, high oil, high sulfur and high organic matter.

[0047] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures indicated in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is a flow chart of a method for extracting deuterium and lithium from produced water in an oil and gas field;

[0049] Figure 2 This is a schematic diagram of a system for extracting deuterium and lithium from produced water in an oil and gas field according to the present application.

[0050] Attached diagram: 1. Flotation device; 2. Blow-off device; 3. Flocculation and sedimentation unit; 4. Sand-carbon filtration unit; 5. Ultrafiltration unit; 6. Lithium ion adsorption device; 7. Nanofiltration device; 8. First electrolysis device; 9. Filtration and purification device; 10. Evaporation and crystallization device; 11. Second electrolysis device; 12. Third electrolysis device. DETAILED DESCRIPTION

[0051] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0052] like Figure 1 As shown, the present application provides a method for extracting deuterium and lithium from produced water in oil and gas fields, comprising:

[0053] Deoiling the produced water from oil and gas fields to obtain deoiled wastewater;

[0054] Desulfurizing the deoiled wastewater to obtain desulfurized wastewater;

[0055] Adsorption pretreatment is performed on the desulfurization wastewater to obtain a pretreatment liquid that removes suspended matter and trace oil droplets;

[0056] Adsorbing lithium ions on the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution;

[0057] Removing divalent cations from the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution;

[0058] Performing a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2;

[0059] Filtering and purifying the concentrated stock solution to obtain a filtrate;

[0060] Adding Na2CO3 into the filtrate and performing precipitation separation to obtain lithium carbonate and mother liquor;

[0061] The mother liquor is evaporated and condensed to obtain NaCl solid and condensed crude heavy water;

[0062] The condensed crude heavy water is subjected to a second electrolysis to obtain heavy water, H2 and O2 as products;

[0063] The product heavy water is electrolyzed for a third time to obtain deuterium gas and O2.

[0064] In some embodiments of the present application, before desulfurization treatment of deoiled wastewater, the process includes:

[0065] Adjust the pH of degreasing wastewater.

[0066] In some embodiments of the present application, desulfurization treatment of deoiled wastewater includes:

[0067] The hydrogen sulfide gas is blown off from the degreasing wastewater by air and then absorbed by NaOH.

[0068] In some embodiments of the present application, adsorbing lithium ions on the pretreatment liquid includes:

[0069] The lithium ions in the pretreatment solution are adsorbed by a manganese-based ion sieving adsorbent.

[0070] In some embodiments of the present application, the produced water from the oil and gas field meets the following conditions: 5≤pH≤8, total organic carbon content≤100mg / L, suspended solid content≤100mg / L, 6mg / L≤Li + Concentration ≤ 300 mg / L, 80 mg / L ≤ S 2- Concentration ≤300mg / L.

[0071] On the other hand, Figure 2 As shown, the present application discloses a system for extracting deuterium and lithium from produced water in oil and gas fields, comprising:

[0072] The flotation device 1 is used to remove oil from the produced water of the oil and gas field to obtain deoiled wastewater;

[0073] The stripping device 2 is used to desulfurize the deoiled wastewater to obtain desulfurized wastewater;

[0074] Adsorption pretreatment device, used for adsorption pretreatment of desulfurization wastewater to obtain pretreated liquid that removes suspended matter and trace oil droplets;

[0075] A lithium ion adsorption device 6 is used to adsorb lithium ions from the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution;

[0076] Nanofiltration device 7, used to remove divalent cations in the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution;

[0077] The first electrolysis device 8 performs a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2;

[0078] The filtration and purification device 9 is used to filter and purify the concentrated raw liquid to obtain a filtrate;

[0079] The evaporation crystallization device 10 is used to add Na2CO3 to the filtrate and perform precipitation separation to obtain lithium carbonate and mother liquor; evaporate and condense the mother liquor to obtain NaCl solid and condensed crude heavy water;

[0080] The second electrolysis device 11 is used to perform a second electrolysis on the condensed crude heavy water to obtain heavy water, H2 and O2 as products;

[0081] The third electrolysis device 12 is used to perform a third electrolysis on the product heavy water to obtain deuterium gas and O2.

[0082] In some embodiments of the present application, the adsorption pretreatment device includes a flocculation and sedimentation unit 3, a sand and carbon filtration unit 4, and an ultrafiltration unit 5, which are connected in sequence to perform multi-precision filtration of suspended matter (large / medium / small particle size) and trace oil droplets in the desulfurization wastewater. The flocculation and sedimentation unit 3 consists of a flocculation and sedimentation tank, a dosing pump, a circulation pump, and a slag discharge facility; the sand and carbon filtration unit 4 consists of a filter and backwash facilities; and the ultrafiltration unit 5 consists of a membrane stack, a pressure pump, and a backwash pump.

[0083] In some embodiments of the present application, the lithium-deficient water is used to backwash the ultrafiltration unit 5 and the filtration purification device 9 or as reinjection water;

[0084] The backwash drainage of the ultrafiltration unit 5 and the filtration purification device 9 is discharged as reinjection water;

[0085] The impurity solution is discharged as reinjection water.

[0086] In some embodiments of the present application, the reinjection water meets the following conditions: pH = 7, total organic carbon content ≤ 100 mg / L, suspended solids content ≤ 1 mg / L, S 2- Concentration ≤5mg / L.

[0087] In some embodiments of the present application, the lithium ion adsorption device 6 includes multiple adsorption towers filled with manganese-based ion sieving adsorbents, which are used to adsorb and desorb lithium ions respectively. For example, it includes three adsorption towers, two towers for adsorption and one tower for desorption, which are switched in turn.

[0088] In order to better illustrate this solution, this application also provides the following examples.

[0089] Example

[0090] according to Figure 2 The assembled system for extracting lithium deuterium from produced water from oil and gas fields is shown, wherein the flotation device 1 includes a cyclonic microbubble flotation device, the stripping device 2 consists of a stripping tower and corresponding pumps, fans, dosing facilities, and gas absorption facilities, the lithium ion adsorption device 6 consists of three adsorption towers, a switching valve, and a regeneration system, the nanofiltration device 7 consists of a membrane stack, a pressure pump, and a cleaning pump, the filtration and purification device 9 consists of a membrane stack, a pressure pump, and a backwash pump, the first electrolysis device 8, the second electrolysis device 11, and the third electrolysis device 12 each consist of an electrolytic cell, a power supply system, and a gas separation system, the evaporation crystallization device 10 consists of an evaporator, a circulation pump, dosing facilities, and solid drying facilities, the flocculation and sedimentation unit 3 consists of a flocculation and sedimentation tank, a dosing pump, a circulation pump, and slag discharge facilities, the sand-carbon filtration unit 4 consists of a filter and backwash facilities, and the ultrafiltration unit 5 consists of a membrane stack, a pressure pump, and a backwash pump.

[0091] The produced water separated from the oil and gas treatment device first enters the flotation device 1. Under the action of flocculants and microbubbles, the oil in the water aggregates to form scum and is removed; the deoiled wastewater enters the stripping tower in the stripping device 2 after pH adjustment, where the hydrogen sulfide gas in the deoiled wastewater is blown out of the liquid phase by air and absorbed by NaOH to obtain desulfurized wastewater; the desulfurized wastewater enters the flocculation and sedimentation device 3, the sand-carbon filtration device 4 and the ultrafiltration device 5 in sequence. As the interception accuracy of the above devices continues to improve, large / medium / small suspended matter and trace oil droplets in the water are intercepted in turn, completing the pre-adsorption process. Pretreatment to obtain a pretreated liquid; the pretreated liquid enters the ion adsorption device 6, which includes three adsorption towers filled with manganese-based ion sieve adsorbents, two towers for adsorption, and one tower for desorption, which are switched in turn. After adsorption, the pretreated liquid obtains lithium-poor water, and the desorption tower desorbs to obtain lithium-rich stock solution. The lithium-poor water is sent to the injection well as reinjection water, or used to backwash the ultrafiltration unit 5 and the filtration purification device 9. The backwash drainage of the ultrafiltration unit 5 and the filtration purification device 9 is discharged as reinjection water, and the lithium-rich stock solution enters the nanofiltration device 7 to remove divalent cation impurities such as calcium and magnesium to obtain Na + 、Li + 、Cl - OH -The electrolyte solution is composed of the main ions and the impurity solution containing the impurity ions; the impurity solution is discharged as reinjection water, and the electrolyte solution enters the first electrolysis device 8. Under the action of the electrodes, light water (H2O) is electrolyzed, and heavy water (D2O) is retained because it is more difficult to electrolyze than light water (H2O). As the solvent light water continues to decrease, H2 and O2 are generated, and the concentration of heavy water and lithium as solutes continues to increase, completing the concentration process and obtaining a concentrated solution; Li-rich + 、D2O、Na + 、Cl - The concentrated raw liquid with suspended impurities enters the filtration purification device 9 to remove the suspended impurities and obtain a filtrate with higher purity; the filtrate enters the evaporation crystallization device 10, in which the Na2CO3 and Li + The reaction is then introduced into the precipitation facility in the evaporation crystallization device 10 for separation to obtain lithium carbonate and mother liquor, and the lithium carbonate is further dried to obtain product lithium carbonate. + 、Cl - The mother liquor is further evaporated to reach a NaCl saturation state, and solids are precipitated. Heavy water (D2O) and light water (H2O) are completely evaporated and condensed to obtain condensed crude heavy water. The condensed crude heavy water enters the second electrolysis device 11, and the light water (H2O) is electrolyzed into hydrogen and oxygen. The condensed crude heavy water is electrolyzed to the required purity to form heavy water, which enters the third electrolysis device 12 and is further electrolyzed into deuterium and oxygen.

[0092] In summary, this application adds a water electrolysis process on the basis of "pretreatment + adsorption + membrane separation + crystallization" that meets the requirements for lithium extraction, and simultaneously extracts deuterium and lithium from oil and gas field produced water, thereby improving product purity and recovery rate, reducing energy consumption, and is suitable for oil and gas field produced water with high salt, high oil, high sulfur, and high organic matter.

[0093] Finally, it should be noted that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for extracting deuterium and lithium from produced water in oil and gas fields, characterized in that: include: Deoiling the produced water from oil and gas fields to obtain deoiled wastewater; performing desulfurization treatment on the deoiled wastewater to obtain desulfurized wastewater; Performing adsorption pretreatment on the desulfurized wastewater to obtain a pretreated liquid from which suspended matter and trace oil droplets are removed; Adsorbing lithium ions on the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution; removing divalent cations from the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution; performing a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2; Filtering and purifying the concentrated stock solution to obtain a filtrate; Adding Na2CO3 to the filtrate and performing precipitation separation to obtain lithium carbonate and mother liquor; The mother liquor is evaporated and condensed to obtain NaCl solid and condensed crude heavy water; performing a second electrolysis on the condensed crude heavy water to obtain heavy water, H2 and O2 as products; The product heavy water is electrolyzed for a third time to obtain deuterium gas and O2.

2. The method for extracting deuterium and lithium from oil and gas field produced water according to claim 1, wherein: Before the deoiling wastewater is subjected to desulfurization treatment, the process includes: The pH of the deoiled wastewater is adjusted.

3. The method for extracting deuterium and lithium from oil and gas field produced water according to claim 1, wherein: The desulfurization treatment of the deoiled wastewater comprises: The hydrogen sulfide gas is blown off from the deoiled wastewater by air and absorbed by NaOH.

4. The method for extracting deuterium and lithium from oil and gas field produced water according to claim 1, wherein: The step of adsorbing lithium ions on the pretreatment liquid comprises: A manganese-based ion sieving adsorbent is used to adsorb lithium ions in the pretreatment solution.

5. The method for extracting deuterium and lithium from oil and gas field produced water according to claim 1, characterized in that: The produced water from the oil and gas field meets the following conditions: 5≤pH≤8, total organic carbon content≤100mg / L, suspended solid content≤100mg / L, 6mg / L≤Li + Concentration ≤ 300 mg / L, 80 mg / L ≤ S 2- Concentration ≤300mg / L.

6. A system for extracting deuterium and lithium from produced water in oil and gas fields, characterized in that: include: An air flotation device (1) is used to remove oil from produced water from oil and gas fields to obtain deoiled wastewater; A stripping device (2) is used to desulfurize the deoiled wastewater to obtain desulfurized wastewater; An adsorption pretreatment device is used to perform adsorption pretreatment on the desulfurized wastewater to obtain a pretreated liquid that removes suspended matter and trace oil droplets; A lithium ion adsorption device (6) is used to adsorb lithium ions on the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution; A nanofiltration device (7) is used to remove divalent cations in the lithium-rich stock solution to obtain an electrolytic stock solution and an impurity solution; a first electrolysis device (8) for performing a first electrolysis on the electrolytic solution to obtain a concentrated solution, H2 and O2; A filtration and purification device (9) is used to filter and purify the concentrated raw liquid to obtain a filtrate; An evaporation crystallization device (10) is used to add Na2CO3 to the filtrate and perform precipitation separation to obtain lithium carbonate and mother liquor; evaporate and condense the mother liquor to obtain NaCl solid and condensed crude heavy water; A second electrolysis device (11) is used to perform a second electrolysis on the condensed crude heavy water to obtain heavy water, H2 and O2 as products; The third electrolysis device (12) is used to perform a third electrolysis on the product heavy water to obtain deuterium gas and O2.

7. The system for extracting deuterium and lithium from oil and gas field produced water according to claim 6, characterized in that: The adsorption pretreatment device comprises a flocculation sedimentation unit (3), a sand carbon filtration unit (4) and an ultrafiltration unit (5) connected in sequence, and is used for filtering suspended matter and trace oil droplets in the desulfurization wastewater with multiple precisions.

8. The system for extracting deuterium and lithium from oil and gas field produced water according to claim 7, characterized in that: The lithium-deficient water is used for backwashing the ultrafiltration unit (5) and the filtration purification device (9) or as reinjection water; The backwash drainage of the ultrafiltration unit (5) and the filtration purification device (9) is discharged as reinjection water; The impurity solution is discharged as reinjection water.

9. The system for extracting deuterium and lithium from oil and gas field produced water according to claim 8, characterized in that: The reinjection water meets the following conditions: pH = 7, total organic carbon content ≤ 100 mg / L, suspended solid content ≤ 1 mg / L, S 2- Concentration ≤5mg / L.

10. The system for extracting deuterium and lithium from oil and gas field produced water according to claim 6, characterized in that: The lithium ion adsorption device (6) comprises a plurality of adsorption towers filled with manganese-based ion sieving adsorbents, which are respectively used for adsorbing and desorbing lithium ions.

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