Treatment process for recycling gas field water associated resources

Abstract

The invention discloses a treatment process for recycling associated resources of gas field water, and relates to the technical field of gas field water treatment. Adsorbing and extracting lithium from the pretreated gas field water, selectively adsorbing lithium ions in the gas field water by adopting a lithium adsorbent, and recycling lithium by using a generated desorption solution; the adsorption tail liquid after lithium extraction is subjected to hardness removal treatment, and divalent hardness ions in the gas field water are removed; evaporating the hardness-removed gas field water to separate out sodium, and cooling and crystallizing mother liquor subjected to sodium separation by evaporation to produce potassium chloride; and extracting bromine from the gas field water subjected to cooling crystallization treatment by adopting an electrooxidation process. Not only is efficient purification of the gas field water achieved, but also the effect of recycling associated resources of the gas field water is achieved in the purification process.

Description

Technical Field

[0001] The invention relates to the technical field of gas field water treatment, and in particular to a treatment process for recycling and utilizing associated resources of gas field water. Background Art

[0002] Gas field water is rich in associated resources, among which the content of lithium ions is 123.6-147.1 mg / L, which is 5-6 times the comprehensive industrial evaluation index; the content of bromide ions is 171.0-233.24 mg / L, which is 3-5 times the comprehensive evaluation index; the content of potassium ions is 2191.8-2530.0 mg / L, which is 2 times the comprehensive evaluation index. In addition to associated resources such as lithium, bromine, and potassium, it also contains a lot of complex impurities such as H2S, suspended matter, oils, organic matter, ammonia nitrogen, etc. Before the associated resources are extracted, the gas field water needs to be pretreated. In addition. The content of resources such as lithium in gas field water is generally lower than that in salt lake brine, and the coexisting elements such as bromine, strontium, and iodine are complex. At the same time, the Sichuan Basin does not have the conditions for natural evaporation and concentration of salt field brine, and the direct extraction technology of low-concentration lithium and other resources in gas field water is more difficult.

[0003] Gas field water is a by-product of gas field exploitation. It has a complex composition and generally contains high levels of impurities such as salts, petroleum, suspended solid particles, and organic chemicals. Directly injecting or discharging gas field water will cause great harm to the formation and its surrounding ecological environment. In the middle and late stages of gas reservoir development, a large amount of gas field water is often produced. With the country's strict requirements on environmental protection and water quality treatment standards, the difficulty of gas field water treatment has gradually increased.

[0004] In the existing technology, gas field water treatment usually adopts the treatment process of simple reinjection after flocculation sedimentation filtration or treatment and discharge after meeting the standards. However, the produced water reinjection treatment process will face the problems of insufficient reinjection capacity of the reinjection system, limited remaining reinjection layer space, and increased difficulty in the approval of new reinjection projects. The gas field water discharge treatment process that meets the standards will face the problems of great treatment difficulty and high treatment cost. The above problems often limit the effective treatment of produced water and affect the smooth and efficient development of gas fields.

[0005] At present, industrial lithium extraction from oil and gas field water is a relatively new topic at home and abroad. There are few mature process technologies and engineering cases for reference, and there are even fewer reports on the comprehensive resource utilization of oil and gas field water. Summary of the invention

[0006] Based on the technical problems existing in the prior art for treating gas field water, the present invention aims to provide a treatment process for recycling and utilizing the associated resources of gas field water, which not only realizes the efficient purification of gas field water, but also realizes the effect of recycling and utilizing its associated resources during the purification process.

[0007] The present invention is achieved through the following technical solutions:

[0008] The present invention provides a treatment process for recycling gas field water associated resources, comprising the following steps:

[0009] Step 1: Pre-treat gas field water;

[0010] Step 2: The pre-treated gas field water is subjected to adsorption and lithium extraction, and a lithium adsorbent is used to selectively adsorb lithium ions in the gas field water, and the resulting desorption liquid is used to recover lithium;

[0011] Step 3: The adsorption tail liquid produced after lithium extraction is subjected to hardness removal treatment to remove divalent hardness ions in the gas field water;

[0012] Step 4: The gas field water after hardness removal is evaporated to precipitate sodium, and the mother liquor after evaporation and precipitation of sodium is cooled and crystallized to produce potassium chloride;

[0013] Step 5: After cooling and crystallization, the gas field water is subjected to electro-oxidation process to extract bromine.

[0014] In the pretreatment of step 1, desulfurization is first performed. Under acidic conditions, air or other gases are introduced into the gas field water to make the gas and liquid fully contact. The H2S dissolved in the water continuously escapes from the liquid phase and enters the gas phase to be removed. The removed H2S is absorbed by the absorption liquid or incinerated. This process can remove 80% to 90% of the sulfides in the gas field water, and can also assist in the secondary desulfurization method of sodium hypochlorite oxidation to remove the remaining sulfides in the gas field water.

[0015] In step one, air is introduced into the gas field water after sulfur removal, and the essential characteristics of air and water are used to generate a large number of nano-sized bubbles in the sewage. Then some tiny impurity particles will adhere to the bubbles and float to the surface with the bubbles, thereby separating the impurities from the clean water. Flocculants are added to remove suspended matter in the gas field water; the gas field water after the suspended matter is removed is subjected to ozone catalytic oxidation to remove organic matter in the gas field water.

[0016] In step 2, lithium ions in the gas field water are selectively adsorbed by lithium adsorbent after pretreatment. After the adsorbent is saturated with adsorption, it is analyzed with soft water or acid. The obtained analyzed liquid is then filtered, nanofiltered, reverse osmosis, ion exchanged to remove calcium, magnesium and boron, and evaporated for concentration.

[0017] In step three, sodium hydroxide is first added to the gas field water to remove magnesium ions, and then sodium carbonate is added to the gas field water after magnesium removal to remove calcium ions, barium ions and strontium ions.

[0018] In step 4, the gas field water after the divalent metal ions are removed is evaporated at high temperature to produce sodium, and industrial-grade sodium chloride (purity ≥ 93%) is produced. At the same time, distilled water is produced, which meets the "Sichuan Province Water Pollutant Discharge Standards", and the main indicators meet: COD ≤ 100 mg / L, petroleum ≤ 10 mg / L, sulfide ≤ 1.0 mg / L, chloride ≤ 300 mg / L. After high-temperature evaporation and sodium precipitation, the mother liquor is cooled and crystallized at low temperature to obtain potassium chloride output (purity ≥ 57%, based on the mass fraction of K2O).

[0019] In step 5, electro-oxidation of bromine is based on Br - With Cl - The standard redox potential formula is different. By choosing the appropriate working electrode potential, the Br - Selective oxidation and extraction of Br - The standard redox potential of Cl - When the working electrode potential is controlled between 1.087 and 1.358 V, that is, the working electrode potential is higher than Br - The standard redox potential is lower than that of Cl - When the standard redox potential of Br - Can be oxidized to Cl - Cannot be oxidized, then Br - Selective electrooxidation.

[0020] The traditional chlorine oxidation bromine extraction process cannot be applied to gas field water. It is necessary to adopt other processes that avoid the use of hazardous chemical chlorine as an oxidant and produce hazardous chemical bromine as the product, or to achieve comprehensive utilization of gas field water bromine resources in other ways.

[0021] Compared with the prior art, the present invention adopts electro-oxidation instead of chlorine oxidation, which can avoid the use of hazardous chemical chlorine in the oxidation process, and the output products are derivatives such as sodium bromide, avoiding the output products being hazardous chemical bromine.

[0022] Compared with the prior art, the whole process of the present invention is that after the gas field water is pretreated, lithium is firstly adsorbed and extracted, and then the divalent metal ions in the gas field water are removed, thereby realizing the effective recovery of the associated resources in the gas field water. At the same time, the divalent metal ions in the gas field water are removed before evaporation and sodium precipitation, thereby solving the scaling problem in the subsequent evaporation and concentration process; by evaporation and sodium precipitation, not only sodium is recovered, but also potassium chloride products are produced; after the metal ions in the gas field water are removed and recovered, bromine in the gas field water is extracted by electro-oxidation, thereby improving the recovery rate of bromine, making the recovery rate of the associated resources in the gas field water in the whole process higher, avoiding the waste of resources, and also reducing the emission of pollutants, thereby realizing the protection of the environment.

[0023] Furthermore, the method for pre-treating the gas field water in step 1 is:

[0024] (1) Under acidic conditions, gas is introduced into the gas field water for stripping treatment to remove H2S from the gas field water;

[0025] (2) adding flocculants to the gas field water after H2S removal to remove suspended matter in the gas field water;

[0026] (3) The gas field water after the suspended matter is removed is subjected to ozone catalytic oxidation to remove organic matter in the gas field water.

[0027] Among them, ozone oxidation of organic matter in gas field water is mainly achieved through direct reaction and indirect reaction. Among them, direct reaction is the direct reaction of ozone with organic matter. This method has strong selectivity and attacks organic matter with double bonds. It is very effective for unsaturated aliphatic hydrocarbons and aromatic hydrocarbon compounds; indirect reaction refers to the decomposition of ozone to produce ·OH, which is oxidized by ·OH with organic matter. This method is not selective. Therefore, when using the ozone catalytic oxidation process to remove organic matter, neither a large amount of mud will be generated nor the loss of bromide ions will be caused, which improves the extraction recovery rate of bromide ions and does not require excessive energy consumption to treat the generated mud.

[0028] Among them, after gas stripping desulfurization, sodium hypochlorite can also be added for secondary desulfurization treatment.

[0029] Furthermore, the acidic condition in step (1) refers to a pH of 3 to 5.

[0030] Furthermore, the flocculant in step (2) includes any one of polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate, and the added amount is 20 to 50 mg / L.

[0031] The flocculant of the present invention adopts an inorganic polymer flocculant because polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate can provide a large amount of complex ions and can strongly adsorb colloidal particles, thereby causing the colloid to condense through adsorption, bridging and cross-linking. At the same time, physical and chemical changes will occur, neutralizing the charges on the surface of the colloidal particles and suspended matter, reducing the delta potential, changing the original mutual repulsion of the colloidal particles to mutual attraction, destroying the stability of the micelle, causing the colloidal particles to collide with each other, thereby forming flocculent coagulation precipitation, and the surface area of ​​the precipitation can reach (200-1000) m 2 / g, with strong adsorption capacity.

[0032] Furthermore, in step (2), a coagulant is added, wherein the coagulant comprises anionic polyacrylamide or sodium alginate, and the added amount is 2 to 5 mg / L.

[0033] In the present invention, in addition to adding an inorganic flocculant, a coagulant aid is added to accelerate the precipitation, play a bonding and bridging role between micro flocs, make the flocs coarse and have a wide surface, give full play to the adsorption and rolling effect, and improve the clarification effect.

[0034] Furthermore, the lithium ions in the gas field water after pretreatment are selectively adsorbed by a lithium adsorbent. After the adsorbent is saturated with adsorption, it is analyzed by soft water or acid. The obtained desorption liquid is then filtered, nanofiltered, reverse osmosis, ion exchanged to remove calcium, magnesium and boron, and evaporated for concentration.

[0035] The present invention sequentially filters, nanofilters, reverses osms, removes calcium, magnesium and boron by ion exchange, and concentrates by evaporation to obtain a qualified concentrated lithium-rich solution, wherein the concentration of lithium ions is ≥20 g / L.

[0036] The concentrated lithium-rich solution is fed to the lithium precipitation area, and a saturated sodium carbonate solution is added to the lithium precipitation area to obtain lithium carbonate precipitate. After centrifugal separation, multiple washings and drying, an industrial-grade lithium carbonate product is obtained with a purity of ≥99%.

[0037] Furthermore, when filtering the desorption liquid, ceramic membrane filtration is adopted.

[0038] Furthermore, the lithium adsorbent in step 2 is one of aluminum-based, titanium-based or manganese-based adsorbents.

[0039] The present invention adopts the method of lithium adsorbent adsorption to extract lithium by utilizing an adsorbent selective for lithium ions to bind lithium ions, and then elutes and extracts the lithium ions under the action of an eluent, thereby separating the lithium ions from other impurity ions.

[0040] Furthermore, the desorption method of the aluminum-based, titanium-based or manganese-based granular adsorbent is as follows: soft water is passed through the saturated aluminum-based adsorbent at a certain flow rate for desorption, and the adsorbent can adsorb lithium again after complete lithium removal; or a hydrochloric acid solution with a concentration of 0.1 to 0.5 mol / L is passed through the saturated titanium-based or manganese-based adsorbent at a certain flow rate for desorption, and the adsorbent can adsorb lithium again after complete lithium removal.

[0041] The adsorbent precursor is LiCl·2Al(OH)3·nH2O or Li4Ti5O 12 , Li2TiO3, or LiMn2O4, Li 1.33 Mn 1.67 O4 or Li4Mn5O 12 Any one of .

[0042] Furthermore, the electro-oxidation bromine extraction process in step five is: the gas field water is adjusted to acidic with hydrochloric acid and then injected into an electro-oxidizer, bromide ions are oxidized into elemental bromine by electro-oxidation, and then introduced into a stripping tower, and the gas blown out is absorbed by sodium hydroxide solution and a reducing agent to obtain a sodium bromide product.

[0043] 3Br2+CO(NH2)2+6NaOH=6NaBr+N2↑+5H2O+CO2↑

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] (1) After the gas field water in the present invention is pretreated, lithium is first adsorbed and extracted, and then the divalent metal ions in the gas field water are removed, thereby achieving effective recovery of associated resources in the gas field water. At the same time, the divalent metal ions in the gas field water are removed before evaporation and sodium precipitation, thereby solving the scaling problem in the subsequent evaporation and concentration process; by evaporation and sodium precipitation, not only sodium is recovered, but also potassium chloride products are produced. After all the metal ions in the gas field water are extracted and recovered, bromine in the gas field water is extracted by electro-oxidation, thereby improving the recovery rate of bromine, making the recovery rate of associated resources in the gas field water in the whole process higher, avoiding waste of resources, and also reducing the emission of pollutants, thereby achieving environmental protection;

[0046] (2) The flocculant of the present invention adopts an inorganic polymer flocculant because polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate can provide a large amount of complex ions and can strongly adsorb colloidal particles, thereby causing the colloid to condense through adsorption, bridging and cross-linking. At the same time, physical and chemical changes will occur, neutralizing the charges on the surface of the colloidal particles and suspended matter, reducing the delta potential, changing the colloidal particles from repelling each other to attracting each other, destroying the stability of the micelle, and causing the colloidal particles to collide with each other, thereby forming a flocculent coagulation precipitate. The surface area of ​​the precipitate can reach (200-1000) m 2 / g, extremely adsorbable;

[0047] (3) In the present invention, when an inorganic flocculant is added, a coagulant aid is added to accelerate the precipitation, play a bonding and bridging role between micro-flocculations, make the flocs coarse and have a wide surface, give full play to the adsorption and rolling effect, and improve the clarification effect;

[0048] (4) The present invention sequentially filters, nanofilters, reverse osms, removes calcium, magnesium and boron by ion exchange, and evaporates and concentrates the desorbed liquid after analysis to obtain a qualified concentrated lithium-rich solution, wherein the concentration of lithium ions is ≥20 g / L;

[0049] (5) The present invention adopts the method of lithium adsorbent adsorption to extract lithium by using an adsorbent that is selective for lithium ions to bind lithium ions, and then elutes and extracts the lithium ions under the action of an eluent, thereby separating the lithium ions from other impurity ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0051] Figure 1 It is a flow chart of a treatment process for recycling and utilizing gas field water associated resources in the present invention;

[0052] Figure 2 The present invention is a process flow chart for extracting bromine by electro-oxidation process. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0054] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Example 1

[0056] Gas field water from a certain area in the Sichuan Basin was taken as a treatment sample. The main water quality characteristics of the gas field water were: pH 6.0, sulfide 100 mg / L, petroleum 20 mg / L, COD 30 mg / L, suspended solids 30 mg / L, lithium ions 140 mg / L, bromide ions 200 mg / L, calcium ions 1000 mg / L, magnesium ions 300 mg / L, barium ions 500 mg / L, and strontium ions 1770 mg / L.

[0057] Reference Figure 1 , the specific processing technology is as follows:

[0058] S1: Pre-treatment of gas field water samples;

[0059] S1-1: Under acidic conditions (pH 3), air is introduced into the gas field water sample to allow the air to fully contact the gas field water liquid. The H2S dissolved in the gas field water continuously escapes from the liquid phase, and the H2S in the gas field water is removed. The removed H2S is absorbed by the absorption liquid.

[0060] S1-2: Add polyaluminium chloride flocculant to the gas field water after H2S removal, with the addition amount of 20mg / L. The complex ions provided by the polyaluminium chloride flocculant strongly adsorb the colloidal particles, and the colloids are condensed through adsorption, bridging and cross-linking. At the same time, physical and chemical changes will occur, neutralizing the charges on the surface of the colloidal particles and suspended matter, reducing the delta potential, and changing the original repulsion of the colloidal particles to attraction, destroying the stability of the flocs, causing the colloidal particles to collide with each other, forming flocculent coagulation precipitation, thereby removing suspended matter in the gas field water.

[0061] S1-3: The gas field water after the suspended solids are removed is subjected to ozone catalytic oxidation. On the one hand, ozone directly reacts with organic matter with double bonds, such as unsaturated aliphatic hydrocarbons and aromatic hydrocarbon compounds. On the other hand, ·OH produced by ozone decomposition reacts with organic matter for oxidation, thereby removing organic matter from the gas field water while ensuring that bromide ions are not lost.

[0062] S2: Lithium is extracted from the pre-treated gas field water by adsorption;

[0063] An aluminum-based adsorbent LiCl·2Al(OH)3·nH2O is selected. The gas field water after the above pretreatment flows through the adsorbent to adsorb and extract lithium. Soft water is passed into the saturated aluminum-based adsorbent at a certain flow rate for desorption. After complete lithium desorption, the adsorbent can adsorb lithium again, and the generated desorption liquid is used to recover lithium.

[0064] S3: The adsorption tail liquid after lithium extraction is subjected to hardness removal treatment to remove divalent hardness ions in gas field water;

[0065] S3-1: First add 20% sodium hydroxide solution to the gas field water to remove magnesium ions.

[0066] S3-2: Add 20% sodium carbonate solution to the gas field water after the magnesium ions are removed to remove calcium ions, barium ions and strontium ions in the gas field water.

[0067] S5: After lithium extraction, the desorption liquid is filtered, nanofiltered, reverse osmosis, ion exchanged to remove calcium, magnesium and boron, and evaporated and concentrated.

[0068] S4: After the divalent metal ions are removed, the gas field water is evaporated at high temperature to precipitate sodium, and industrial-grade sodium chloride is produced. At the same time, distilled water is produced, and the main indicators of the gas field water after treatment meet the following requirements: COD ≤ 100 mg / L, petroleum ≤ 10 mg / L, sulfide ≤ 1.0 mg / L, chloride ≤ 300 mg / L. After the high-temperature evaporation and precipitation of sodium, the mother liquor is cooled and crystallized at low temperature to obtain potassium chloride output (purity ≥ 57%, based on the mass fraction of K2O).

[0069] S5: After cooling and crystallization, the gas field water is treated with electro-oxidation process to extract bromine;

[0070] S5-1: The gas field water is adjusted to pH 3 with hydrochloric acid, and the acid-adjusted gas field water is pumped into an electro-oxidizer. The working electrode potential is controlled between 1.087 and 1.358 V. The bromide ions are oxidized into elemental bromine through electro-oxidation, and then introduced into a stripping tower. The gas after blowing out is absorbed by sodium hydroxide solution and a reducing agent (urea) to obtain a 45% sodium bromide output product.

[0071] The gas field water treated by the above method is directly returned to the raw water tank.

[0072] During the treatment process, the content of related substances in the gas field water after each step of treatment was tested, and the test results are shown in Table 1 below.

[0073] Table 1

[0074]

[0075]

[0076] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0077] Example 2

[0078] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0079] In terms of treatment process, the difference between this embodiment and embodiment 1 is that when removing H2S from gas field water in this embodiment, the pH value of the acidic condition is 4. Other technical features are exactly the same as those of embodiment 1.

[0080] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 2 were tested. The test results are shown in Table 2 below.

[0081] Table 2

[0082]

[0083] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0084] Example 3

[0085] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0086] In terms of treatment process, the difference between this embodiment and embodiment 1 is that when removing H2S from gas field water in this embodiment, the pH value of the acidic condition is 5. Other technical features are exactly the same as those of embodiment 1.

[0087] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 3 were tested. The test results are shown in Table 3 below.

[0088] Table 3

[0089]

[0090] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0091] It can be seen from the data of Examples 1 to 3 that within the pH value range specified in the present application, only the H2S removal rate fluctuates, but it is maintained at above 99%, and has almost no effect on the purification rate of other gas field waters, indicating that within the pH value range specified in the present application, gas field water can achieve good purification effects.

[0092] Example 4

[0093] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0094] In terms of treatment process, the difference between this embodiment and embodiment 1 is that the flocculant used in this embodiment is polyaluminum sulfate, and other technical features are exactly the same as those in embodiment 1.

[0095] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 4 were tested. The test results are shown in Table 4 below.

[0096] Table 4

[0097]

[0098]

[0099] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0100] Example 5

[0101] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0102] In terms of treatment process, the difference between this embodiment and embodiment 1 is that the flocculant used in this embodiment is polyferric chloride, and other technical features are exactly the same as those in embodiment 1.

[0103] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 5 were tested. The test results are shown in Table 5 below.

[0104] Table 5

[0105]

[0106] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0107] And by comparing Example 1, Example 4 and Example 5, it can be found that no matter whether polyaluminum chloride, polyaluminum sulfate or polyferric chloride is used as the flocculant, the removal rate of solid particles is very small, and can reach more than 99%, indicating that polyaluminum chloride, polyaluminum sulfate and polyferric chloride all have good flocculation effects.

[0108] Example 6

[0109] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0110] In terms of treatment process, the difference between this embodiment and embodiment 1 is that the amount of flocculant added in this embodiment is 30 mg / L, and other technical features are exactly the same as those in embodiment 1.

[0111] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 6 were tested. The test results are shown in Table 6 below.

[0112] Table 6

[0113]

[0114] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0115] Example 7

[0116] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0117] In terms of treatment process, the difference between this embodiment and embodiment 1 is that the amount of flocculant added in this embodiment is 50 mg / L, and other technical features are exactly the same as those in embodiment 1.

[0118] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 7 were tested. The test results are shown in Table 7 below.

[0119] Table 7

[0120]

[0121] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0122] And by comparing Example 1, Example 6 and Example 7, it can be seen that the more flocculants are added, the better the flocculation effect, the higher the removal rate of suspended solids, and the removal rate of petroleum is also improved, and the removal rates are all above 99%, indicating that the dosage specified in this application can have a good promoting effect on the purification of suspended solids and petroleum.

[0123] Example 8

[0124] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0125] In terms of treatment process, the difference between this embodiment and embodiment 1 is that in addition to the flocculant, 2 mg / L of anionic polyacrylamide is also added in this embodiment, and the other technical features are exactly the same as those in embodiment 1.

[0126] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 8 were tested. The test results are shown in Table 8 below.

[0127] Table 8

[0128]

[0129]

[0130] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0131] Example 9

[0132] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0133] In terms of treatment process, the difference between this embodiment and embodiment 1 is that in addition to the flocculant, 3 mg / L of anionic polyacrylamide is also added in this embodiment, and the other technical features are exactly the same as those in embodiment 1.

[0134] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 9 above were tested. The test results are shown in Table 9 below.

[0135] Table 9

[0136]

[0137] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0138] Example 10

[0139] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0140] In terms of treatment process, the difference between this embodiment and embodiment 1 is that in addition to the flocculant, 5 mg / L of anionic polyacrylamide is also added in this embodiment, and the other technical features are exactly the same as those in embodiment 1.

[0141] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 10 above were tested. The test results are shown in Table 10 below.

[0142] Table 10

[0143]

[0144] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0145] Embodiment 11

[0146] The gas field water sample processed in this embodiment is the same as that in the embodiment.

[0147] In terms of treatment process, the difference between this embodiment and embodiment 1 is that in addition to the flocculant, 2 mg / L sodium alginate is also added in this embodiment, and the other technical features are exactly the same as those in embodiment 1.

[0148] The concentrations of sulfide, petroleum, COD, suspended solids, lithium ions, calcium ions, magnesium ions, barium ions, and strontium ions in the gas field water treated by the method of Example 11 above were tested. The test results are shown in Table 11 below.

[0149] Table 11

[0150]

[0151]

[0152] It can be seen from the test data in the above table that the pollutant purification rate in the gas field water after treatment by the treatment method of the present invention is above 99%, indicating that the gas field water treatment process in the present application has a good purification effect, and can also realize the recovery of associated resources in the gas field water during the purification process, thereby reducing pollution to the environment while realizing the recycling of resources.

[0153] And by comparing the test data in Example 1, Example 8 to Example 11, it can be seen that after adding the coagulant, the flocculation and sedimentation effect of the solid particles is better, the removal rate is higher, and within the dosage range specified in the present application, the removal rate can reach more than 99%. At the same time, the use of sodium alginate as a coagulant can also achieve a removal effect that is not much different from that of anionic polyacrylamide, indicating that sodium alginate as a coagulant can also play a good role in promoting the flocculation effect of the flocculant.

[0154] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A treatment process for recycling gas field water associated resources, characterized in that: The following steps are involved: Step 1: Pre-treat gas field water; Step 2: The pre-treated gas field water is subjected to adsorption and lithium extraction, and a lithium adsorbent is used to selectively adsorb lithium ions in the gas field water, and the resulting desorption liquid is used to recover lithium; Step 3: The adsorption tail liquid after lithium extraction is subjected to hardness removal treatment to remove divalent hardness ions in the gas field water; Step 4: The gas field water after hardness removal is evaporated to precipitate sodium, and the mother liquor after evaporation and precipitation of sodium is cooled and crystallized to produce potassium chloride; Step 5: After cooling and crystallization, the gas field water is subjected to electro-oxidation process to extract bromine.

2. A treatment process for recycling gas field water associated resources according to claim 1, characterized in that: The method for pre-treating gas field water in step 1 is: (1) Under acidic conditions, gas is introduced into the gas field water for stripping treatment to remove H2S from the gas field water; (2) adding flocculants to the gas field water after H2S removal to remove suspended matter in the gas field water; (3) The gas field water after the suspended matter is removed is subjected to ozone catalytic oxidation to remove organic matter in the gas field water.

3. A treatment process for recycling gas field water associated resources according to claim 2, characterized in that: The acidic condition in step (1) refers to a pH of 3 to 5.

4. A treatment process for recycling gas field water associated resources according to claim 2, characterized in that: The flocculant in step (2) includes any one of polyaluminium chloride, polyaluminium sulfate, polyferric chloride and polyferric sulfate, and the added amount is 20 to 50 mg / L.

5. A treatment process for recycling gas field water associated resources according to claim 2, characterized in that: In step (2), a coagulant is also added, and the coagulant includes anionic polyacrylamide or sodium alginate, and the added amount is 2-5 mg / L.

6. The process for recycling gas field water associated resources according to claim 1, characterized in that: After pretreatment, lithium adsorbent is used to selectively adsorb lithium ions in the gas field water. After the adsorbent is saturated with adsorption, it is analyzed with soft water or acid. The obtained analyzed liquid is then filtered, nanofiltered, reverse osmosis, ion exchanged to remove calcium, magnesium and boron, and evaporated for concentration.

7. A treatment process for recycling gas field water associated resources according to claim 6, characterized in that: When filtering the analytical solution, ceramic membrane filtration is used.

8. The process for recycling gas field water associated resources according to claim 1, characterized in that: The lithium adsorbent in step 2 is one of aluminum-based, titanium-based or manganese-based granular adsorbents.

9. A treatment process for recycling gas field water associated resources according to claim 8, characterized in that: The desorption method of the aluminum-based, titanium-based or manganese-based granular adsorbent is as follows: soft water is passed through the saturated aluminum-based adsorbent at a certain flow rate for desorption, and the adsorbent can adsorb lithium again after desorption is complete; or a hydrochloric acid solution with a concentration of 0.1 to 0.5 mol / L is passed through the saturated titanium-based or manganese-based adsorbent at a certain flow rate for desorption, and the adsorbent can adsorb lithium again after desorption is complete.

10. The process for recycling gas field water associated resources according to claim 1, characterized in that: The electro-oxidation bromine extraction process in step five is: the gas field water is adjusted to acidic with hydrochloric acid and then pumped into the electro-oxidizer, the bromide ions are oxidized into elemental bromine by electro-oxidation, and then introduced into the stripping tower, and the gas blown out is absorbed by sodium hydroxide solution and a reducing agent to obtain a sodium bromide product.

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