A method and system for extracting deuterium and lithium from produced water in oil and gas fields

Abstract

This application belongs to the field of methods for extracting associated minerals, and discloses a method and system for extracting deuterium and lithium from produced water in oil and gas fields. The method includes sequentially performing oil removal treatment, desulfurization treatment, adsorption pretreatment, lithium ion adsorption, removal of divalent cations, first electrolysis, filtration purification, addition of Na2CO3, evaporation and condensation, second electrolysis, and third electrolysis on the produced water, simultaneously extracting deuterium and lithium from the produced water. This application adds an electrolysis process to the existing "pretreatment + adsorption + membrane separation + crystallization" process that meets the requirements for lithium extraction, simultaneously extracting deuterium and lithium. Through system optimization, it improves product purity and recovery rate while reducing energy consumption.

Description

Technical Field

[0001] This application belongs to the field of methods for extracting associated minerals, and in particular relates to a method and system for extracting lithium deuterium from produced water in oil and gas fields. Background Technology

[0002] Produced water from oil and gas fields is characterized by its massive output, complex composition, and high treatment costs, which has long plagued oil and gas production companies. Lithium, known as "white oil," is a key element required for strategic emerging industries and future industries such as electrochemical energy storage and nuclear fusion. From 2010 to 2022, global lithium mine production increased fivefold. Natural water contains 145-155 ppm of deuterium. Heavy water (D2O) is a fundamental material for nuclear energy development. Heavy water has a different boiling point than ordinary water, so it can be purified by distillation. The electrolysis rate of heavy water is lower than that of ordinary water, so it can also be extracted by electrolysis. In the Southwest Oil and Gas Field, Qaidam Basin, Tarim Basin, and Jianghan Basin, approximately half of the produced water from wellheads has a lithium ion concentration of 6-300 mg / L, which has 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. This method should couple membrane separation, adsorption, and electrolysis processes to meet the reinjection requirements, thereby maximizing the needs for green electricity consumption and deuterium and lithium extraction. This will enable the resource utilization of associated minerals in oil and gas field water, turning waste into treasure. Summary of the Invention

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

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

[0006] A method for extracting lithium deuterium from produced water in an oil and gas field includes:

[0007] Oil-removed wastewater is obtained by treating produced water from oil and gas fields to remove oil.

[0008] Oil-removing wastewater is desulfurized to obtain desulfurized wastewater.

[0009] The desulfurization wastewater was pretreated by adsorption to obtain a pretreated solution with suspended solids and trace oil droplets removed.

[0010] Lithium ion adsorption was performed on the pretreatment solution to obtain lithium-poor water and lithium-rich stock solution;

[0011] Divalent cations are removed from the lithium-rich stock solution to obtain the electrolyte stock solution and the impurity solution;

[0012] The electrolyte solution is subjected to a first electrolysis to obtain concentrated electrolyte, H2 and O2;

[0013] The concentrated stock solution was filtered and purified to obtain the filtrate;

[0014] Na2CO3 was added to the filtrate and precipitation was carried out to obtain lithium carbonate and mother liquor;

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

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

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

[0018] Furthermore, before desulfurizing the oil-removing wastewater, the following steps are taken:

[0019] pH adjustment is performed on the oil-removed wastewater.

[0020] Furthermore, the oil-removed wastewater undergoes desulfurization treatment, including:

[0021] Hydrogen sulfide gas is blown off from the oil-removed wastewater using air and then absorbed by NaOH.

[0022] Further, lithium ion adsorption is performed on the pretreatment solution, including:

[0023] Lithium ions in the pretreatment solution were adsorbed using a manganese-based ion-sieving adsorbent.

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

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

[0026] An air flotation device is used to remove oil from produced water from oil and gas fields, producing oil-free wastewater.

[0027] The stripping device is used to desulfurize oil-removed wastewater to obtain desulfurized wastewater;

[0028] An adsorption pretreatment device is used to pretreat desulfurization wastewater by adsorption to obtain a pretreated liquid with suspended solids and trace oil droplets removed.

[0029] A lithium-ion adsorption device is used to adsorb lithium ions into a pretreatment solution to obtain lithium-poor water and lithium-rich stock solution.

[0030] Nanofiltration device is used to remove divalent cations from lithium-rich feed solution to obtain electrolyte and impurity solution;

[0031] The first electrolysis device is used to electrolyze the electrolyte for the first time to obtain concentrated electrolyte, H2 and O2;

[0032] A filtration and purification device is used to filter and purify concentrated stock solution to obtain filtrate;

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

[0034] The second electrolysis unit is used to electrolyze the condensed crude heavy water a second time to obtain the product heavy water, H2 and O2;

[0035] The third electrolysis unit is used to electrolyze the heavy water of the product for the third time to obtain deuterium and O2.

[0036] Furthermore, the adsorption pretreatment device includes a flocculation sedimentation unit, a sand and carbon filtration unit, and an ultrafiltration unit connected in sequence, which are used to filter suspended solids and trace oil droplets in desulfurization wastewater with high precision.

[0037] Furthermore, lithium-poor water is used for backwashing ultrafiltration units and filtration purification devices or as feed water;

[0038] The backwash water from 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 reinjected water meets the following conditions: pH = 7, total organic carbon content ≤ 100 mg / L, suspended solids content ≤ 1 mg / L, and S... 2- Concentration ≤ 5 mg / L.

[0041] Furthermore, the lithium-ion adsorption device includes multiple 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 as follows:

[0043] 1. The method of this application makes full use of membrane separation, adsorption and other processes to concentrate and purify important mineral lithium in stages, 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 this application can utilize surplus renewable energy 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 benefits.

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

[0046] 4. This application has broad water quality adaptability and is applicable to produced water from oil and gas fields with high salinity, high oil content, high sulfur content, and high organic matter content.

[0047] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating a method for extracting lithium deuterium from produced water in an oil and gas field, as described in this application.

[0049] Figure 2 This is a schematic diagram of a system for extracting lithium deuterium from produced water in an oil and gas field, as described in this application.

[0050] The attached diagram shows: 1. Air flotation device; 2. Stripping device; 3. Flocculation and sedimentation unit; 4. Sand and 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 Implementation

[0051] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

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

[0053] Oil-removed wastewater is obtained by treating produced water from oil and gas fields to remove oil.

[0054] Oil-removing wastewater is desulfurized to obtain desulfurized wastewater.

[0055] The desulfurization wastewater was pretreated by adsorption to obtain a pretreated solution with suspended solids and trace oil droplets removed.

[0056] Lithium ion adsorption was performed on the pretreatment solution to obtain lithium-poor water and lithium-rich stock solution;

[0057] Divalent cations are removed from the lithium-rich stock solution to obtain the electrolyte stock solution and the impurity solution;

[0058] The electrolyte solution is subjected to a first electrolysis to obtain concentrated electrolyte, H2 and O2;

[0059] The concentrated stock solution was filtered and purified to obtain the filtrate;

[0060] Na2CO3 was added to the filtrate and precipitation was carried out to obtain lithium carbonate and mother liquor;

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

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

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

[0064] In some embodiments of this application, the process of desulfurizing the oily wastewater includes:

[0065] pH adjustment is performed on the oil-removed wastewater.

[0066] In some embodiments of this application, desulfurization treatment of oily wastewater includes:

[0067] Hydrogen sulfide gas is blown off from the oil-removed wastewater using air and then absorbed by NaOH.

[0068] In some embodiments of this application, lithium-ion adsorption of the pretreatment solution includes:

[0069] Lithium ions in the pretreatment solution were adsorbed using a manganese-based ion-sieving adsorbent.

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

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

[0072] Air flotation device 1 is used to remove oil from produced water from oil and gas fields to obtain oil-removed wastewater;

[0073] Stripping device 2 is used to desulfurize oil-removed wastewater to obtain desulfurized wastewater;

[0074] An adsorption pretreatment device is used to pretreat desulfurization wastewater by adsorption to obtain a pretreated liquid with suspended solids and trace oil droplets removed.

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

[0076] Nanofiltration device 7 is used to remove divalent cations from lithium-rich feed solution to obtain electrolyte feed solution and impurity solution;

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

[0078] The filtration and purification device 9 is used to filter and purify the concentrated stock solution to obtain the filtrate.

[0079] Evaporation crystallization apparatus 10 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;

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

[0081] The third electrolysis unit 12 is used to perform a third electrolysis of the heavy water in the product to obtain deuterium and O2.

[0082] In some embodiments of this application, the adsorption pretreatment device includes a flocculation sedimentation unit 3, a sand-carbon filtration unit 4, and an ultrafiltration unit 5 connected in sequence, used for multi-precision filtration of suspended solids (large / medium / small particle sizes) and trace oil droplets in desulfurization wastewater. The flocculation sedimentation unit 3 consists of a flocculation sedimentation tank, a dosing pump, a circulation pump, and slag discharge facilities; the sand-carbon filtration unit 4 consists of a filter and a backwashing facility; and the ultrafiltration unit 5 consists of a membrane stack, a pressurizing pump, and a backwashing pump.

[0083] In some embodiments of this application, lithium-poor water is used for backwashing the ultrafiltration unit 5 and the filtration purification device 9 or as reinjection water.

[0084] The backwash water from ultrafiltration unit 5 and filtration purification device 9 is discharged as reinjection water.

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

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

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

[0088] To better illustrate this solution, the following embodiments are also provided in this application.

[0089] Example

[0090] according to Figure 2 The system shown is an assembly for extracting lithium deuterium from produced water in an oil and gas field. The assembly includes: an air flotation unit 1 comprising a cyclone microbubble air flotation unit; a stripping unit 2 consisting of a stripping tower and corresponding pumps, blowers, dosing equipment, and gas absorption equipment; a lithium-ion adsorption unit 6 consisting of three adsorption towers, a switching valve, and a regeneration system; a nanofiltration unit 7 consisting of a membrane stack, a pressurizing pump, and a cleaning pump; a filtration and purification unit 9 consisting of a membrane stack, a pressurizing pump, and a backwashing pump; a first electrolysis unit 8, a second electrolysis unit 11, and a third electrolysis unit 12 each consisting of an electrolytic cell, a power supply system, and a gas separation system; an evaporation and crystallization unit 10 consisting of an evaporator, a circulating pump, dosing equipment, and a solid drying system; a flocculation and sedimentation unit 3 consisting of a flocculation and sedimentation tank, a dosing pump, a circulating pump, and a slag discharge system; a sand and carbon filtration unit 4 consisting of a filter and a backwashing system; and an ultrafiltration unit 5 consisting of a membrane stack, a pressurizing pump, and a backwashing pump.

[0091] Produced water separated from the oil and gas processing unit first enters the flotation unit 1. Under the action of flocculants and microbubbles, oil in the water aggregates to form scum and is removed. After pH adjustment, the oil-removed wastewater enters the stripping tower in the stripping unit 2. Hydrogen sulfide gas in the oil-removed wastewater is blown out of the liquid phase by air in the stripping tower and absorbed by NaOH to obtain desulfurized wastewater. The desulfurized wastewater then sequentially enters the flocculation sedimentation unit 3, the sand and carbon filtration unit 4, and the ultrafiltration unit 5. As the interception accuracy of the above devices continuously improves, large / medium / small suspended solids and trace oil droplets in the water are intercepted in sequence, completing the process before adsorption. Pretreatment yields a pretreated solution. This pretreated solution enters an ion adsorption unit 6, which contains three adsorption towers filled with manganese-based ion-sieving adsorbents. Two towers adsorb, and one tower desorbs, alternating between the two. After adsorption, the pretreated solution yields lithium-poor water. The desorption tower then desorbs the lithium-rich stock solution. This lithium-poor water is sent to an injection well as reinjection water or used for backwashing the ultrafiltration unit 5 and the filtration purification unit 9. The backwash water from the ultrafiltration unit 5 and the filtration purification unit 9 is discharged as reinjection water. The lithium-rich stock solution enters a nanofiltration unit 7 to remove divalent cation impurities such as calcium and magnesium, yielding a solution with Na+. + Li + Cl - OH -The electrolyte consists of a stock solution containing the main ions and an impurity solution containing impurity ions. The impurity solution is discharged as reinjection water, and the stock solution enters the first electrolysis device 8. Under the action of the electrodes, light water (H2O) is electrolyzed, while heavy water (D2O) is retained because it is more difficult to electrolyze than light water (H2O). As the solvent light water decreases, H2 and O2 are generated, and the concentrations of heavy water and lithium as solutes increase, completing the concentration process and obtaining a concentrated stock solution rich in Li. + D2O, Na + Cl - The concentrated stock solution containing suspended impurities enters the filtration and purification device 9 to remove suspended impurities and obtain a filtrate with higher purity; the filtrate then enters the evaporation and crystallization device 10, where Na2CO3 and Li are added. + The reaction proceeds, and then the mixture is introduced into the precipitation apparatus of the evaporation crystallization unit 10 for separation, yielding lithium carbonate and mother liquor. The lithium carbonate is further dried to obtain the product lithium carbonate. (The remaining text appears to be incomplete and contains tyrosine. A more accurate translation would require the full context.) + Cl - After the mother liquor is further evaporated to reach NaCl saturation, 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, where light water (H2O) is electrolyzed into hydrogen and oxygen. After the condensed crude heavy water reaches the required purity through electrolysis, it forms heavy water which enters the third electrolysis device 12 and is further electrolyzed into deuterium and oxygen.

[0092] In summary, this application adds an electrolysis process to the existing "pretreatment + adsorption + membrane separation + crystallization" process to simultaneously extract deuterium and lithium from produced water in oil and gas fields, thereby improving product purity and recovery rate, reducing energy consumption, and making it suitable for produced water from oil and gas fields with high salt, high oil, high sulfur, and high organic matter content.

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

Claims

1. A method for extracting lithium deuterium from produced water in oil and gas fields, characterized in that, include: Oil-removed wastewater is obtained by treating produced water from oil and gas fields to remove oil. The oil-removed wastewater is subjected to desulfurization treatment to obtain desulfurized wastewater; The desulfurization wastewater was subjected to adsorption pretreatment to obtain a pretreated liquid in which suspended solids and trace oil droplets were removed. The pretreated solution is subjected to lithium ion adsorption to obtain lithium-poor water and lithium-rich stock solution; The divalent cations in the lithium-rich stock solution are removed to obtain the electrolyte stock solution and the impurity solution; The electrolyte solution is subjected to a first electrolysis to obtain a concentrated solution, H2, and O2; The concentrated stock solution is filtered and purified to obtain the filtrate; Na2CO3 was added to the filtrate and precipitation was carried out to obtain lithium carbonate and mother liquor; The mother liquor was evaporated and condensed to obtain solid NaCl and condensed crude heavy water; The condensed crude heavy water is subjected to a second electrolysis to obtain product heavy water, H2 and O2; The heavy water in the product is subjected to a third electrolysis to obtain deuterium gas and O2.

2. The method for extracting lithium deuterium from produced water in oil and gas fields according to claim 1, characterized in that, Before desulfurizing the oil-removed wastewater, the process includes: The pH of the oil-removed wastewater was adjusted.

3. The method for extracting lithium deuterium from produced water in an oil and gas field according to claim 1, characterized in that, The desulfurization treatment of the oil-removed wastewater includes: Hydrogen sulfide gas is blown off from the oil-removed wastewater using air and then absorbed by NaOH.

4. The method for extracting lithium deuterium from produced water in an oil and gas field according to claim 1, characterized in that, The lithium-ion adsorption of the pretreatment solution includes: Lithium ions in the pretreatment solution are adsorbed using a manganese-based ion-sieving adsorbent.

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

6. A system for extracting lithium deuterium 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 oil-removed wastewater. The stripping device (2) is used to desulfurize the oil-removed wastewater to obtain desulfurized wastewater; An adsorption pretreatment device is used to pretreat the desulfurization wastewater by adsorption to obtain a pretreated liquid with suspended solids and trace oil droplets removed. A lithium-ion adsorption device (6) is used to adsorb lithium ions onto the pretreatment liquid to obtain lithium-poor water and lithium-rich stock solution. Nanofiltration device (7) is used to remove divalent cations from the lithium-rich stock solution to obtain an electrolyte stock solution and an impurity solution; The first electrolysis device (8) is used to perform the first electrolysis on the electrolyte to obtain concentrated electrolyte, H2 and O2; The filtration and purification device (9) is used to filter and purify the concentrated stock solution to obtain the filtrate. An evaporation crystallization apparatus (10) 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; The second electrolysis device (11) is used to perform a second electrolysis on the condensed crude heavy water to obtain product heavy water, H2 and O2; The third electrolysis device (12) is used to electrolyze the heavy water of the product for the third time to obtain deuterium and O2.

7. A system for extracting lithium deuterium from produced water in an oil and gas field according to claim 6, characterized in that, The adsorption pretreatment device includes a flocculation sedimentation unit (3), a sand and carbon filtration unit (4), and an ultrafiltration unit (5) connected in sequence, which are used to filter suspended solids and trace oil droplets in the desulfurization wastewater with high precision.

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

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

10. A system for extracting lithium deuterium from produced water in an oil and gas field according to claim 6, characterized in that, The lithium-ion adsorption device (6) includes multiple adsorption towers filled with manganese-based ion sieve adsorbents, which are used for adsorbing and desorbing lithium ions respectively.

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