A method and system for resourceful treatment of high salinity gas field water
By converting highly salinized gas field water into compounds such as sodium bicarbonate and soda ash through pretreatment and chemical reaction steps, the environmental protection and resource utilization issues of highly salinized gas field water treatment are solved, achieving zero discharge and efficient resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2024-11-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing technologies for treating high-mineralization gas field water are subject to environmental policy restrictions, high costs, and operational difficulties, and are also difficult to achieve effective resource utilization.
By employing steps such as pretreatment, mother liquor generation, sodium bicarbonate generation, ammonium chloride generation, ammonium sulfate generation, and ammonium sulfate decomposition, compounds such as sodium bicarbonate and soda ash are generated through evaporation concentration and chemical reactions, thereby achieving the resource-based treatment of gas field water.
It has achieved zero discharge and resource utilization of high-mineralized gas field water, reduced production costs, reduced greenhouse gas emissions, and improved resource efficiency, thus having significant economic and environmental benefits.
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Figure CN122102401A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of oil and gas extraction, and more particularly to a method and system for the resource-based treatment of highly salinized gas field water. Background Technology
[0002] With the intensification of domestic gas field development, the total amount of produced water from gas fields is constantly increasing. Currently, the main methods for treating domestic gas field water are either reinjection into the formation after treatment or discharge.
[0003] The main process for reinjecting formation water involves adjusting subsidence and adding oil removal or filtration units depending on water quality. After treatment, the produced water is stored in deep, porous rock formations. Reinjecting gas field water is relatively inexpensive and simple to implement. However, in recent years, formation water reinjection has been restricted by some local environmental protection policies. At the same time, the reinjection pressure in some gas fields is increasing, and the selection of injection wells is more difficult, which has increased the implementation cost of reinjection measures.
[0004] Discharge refers to the process of purifying produced water from gas fields to meet relevant discharge standards before releasing it into natural water bodies or soil. High-mineralized gas field water has a TDS (Total Dissolved Solids) between 10,000 and 200,000 and contains a large amount of inorganic salt ions, such as sodium. + K + Mg 2+ Ca 2+ Cl - Furthermore, gas field water contains impurities such as oil, suspended solids, heavy metals, and recalcitrant organic matter. The COD (Chemical Oxygen Demand) level is a strict control indicator for discharge, requiring deep treatment or evaporation to meet discharge standards. With the implementation of the new Environmental Protection Law, existing methods for achieving compliant discharge suffer from drawbacks such as lengthy processes, high investment costs, complex operation, and stringent maintenance requirements.
[0005] Therefore, there is a need for an improved method and system for the resource-based treatment of highly salinized gas field water. Summary of the Invention
[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.
[0007] This application provides a resource-based treatment method for high-mineralization gas field water, including a pretreatment section, a mother liquor generation section, a sodium bicarbonate generation section, an ammonium chloride generation section, an ammonium sulfate generation section, and an ammonium sulfate decomposition section; The pretreatment section includes removing impurities from the gas field water; The mother liquor generation section includes evaporating pretreated gas field water to generate a mother liquor containing a saturated sodium chloride aqueous solution. The sodium bicarbonate generation section includes introducing ammonia gas into the mother liquor to saturate the amount of dissolved ammonia gas in the mother liquor; and continuing to introduce carbon dioxide into the mother liquor to precipitate sodium bicarbonate solid from the mother liquor and filter to obtain sodium bicarbonate. The ammonium chloride generation section includes cooling the mother liquor from which the sodium bicarbonate solid has been removed to below 10°C to precipitate ammonium chloride solid and then filtering it to obtain ammonium chloride. The ammonium sulfate generation section includes introducing ammonium bisulfate to react with the ammonium chloride generated in the ammonium chloride generation section to produce ammonium sulfate and hydrogen chloride; The ammonium sulfate decomposition section includes the decomposition of ammonium sulfate to generate ammonia and ammonium hydrogen sulfate.
[0008] As described in this application, the term "high-mineralization gas field water" refers to formation water with high mineralization (salt content) generated during the natural gas extraction process, which typically has a mineralization of tens of thousands to hundreds of thousands of mg / L or higher. Gas field water contains ions such as potassium, sodium, calcium, and magnesium, as well as iodine and boron ions, and a large amount of suspended solids, oil, sulfides, and organic matter such as oilfield chemical additives.
[0009] In this application, the term "impurity" may refer to oil, suspended solids, organic matter, etc. in gas field water.
[0010] In one embodiment, the pretreatment stage may include one or more steps such as homogenization, oil removal, removal of suspended solids, hardness reduction, pH adjustment, oxidation treatment, and filtration. The purpose of these steps is to remove impurities such as oil, suspended solids, and organic matter from the gas field water, and to reduce the hardness of the gas field water, thereby ensuring the smooth progress of subsequent resource recovery methods and the quality of the output.
[0011] In one embodiment, the steps of adjusting homogenization, degreasing, and removing suspended solids are used to further remove impurities such as oil and suspended solids.
[0012] In one embodiment, the hardness reduction step may include removing heavy metal ions such as mercury so that the heavy metal content in the gas field water meets the corresponding standards of the "Discharge Standard of Water Pollutants for Urban Wastewater Treatment Plants".
[0013] In one embodiment, after the pH adjustment step, the pH of the gas field water is in a near-neutral range, such as 6.5-7.0.
[0014] In one embodiment, the oxidation step is used to remove organic pollutants, and the oxidation method may include any one of Fenton oxidation, electrocatalysis, and ozone oxidation.
[0015] The method described in this application is particularly suitable for gas field water with a high sodium ion content. If the calcium ion content in the gas field water is high, calcium ions can be removed in the pretreatment stage by methods such as precipitation.
[0016] In the mother liquor generation section, the pretreated gas field water is evaporated and concentrated to obtain a saturated concentrated brine solution mainly composed of sodium chloride and condensed purified water.
[0017] In one embodiment, the energy used for evaporation and concentration can be natural gas produced in the gas field to achieve low-cost operation and stable energy supply.
[0018] In one embodiment, the reaction temperature after introducing carbon dioxide in the sodium bicarbonate generation section is 32-38°C.
[0019] In one embodiment, the carbon dioxide introduced in the sodium bicarbonate generation section can be obtained from the collection and production of tail gas from the gas field natural gas purification plant, in order to reduce operating costs and achieve green and low-carbon production.
[0020] In one embodiment, the ammonium sulfate generation section includes heating ammonium bisulfate to its melting point, adding ammonium chloride generated in the ammonium chloride generation section under stirring, generating ammonium sulfate and hydrogen chloride at 140-160°C, and emitting hydrogen chloride gas; In one embodiment, the molar ratio of ammonium bisulfate to ammonium chloride is greater than 1:0.5.
[0021] In one embodiment, the emitted hydrogen chloride is converted into hydrochloric acid and returned to the pH adjustment step of the pretreatment section.
[0022] In one embodiment, the resource recovery method further includes returning at least a portion of the mother liquor remaining after removing solid ammonium chloride in the ammonium chloride generation section to the pretreatment section.
[0023] In one embodiment, in the ammonium sulfate decomposition section, the temperature is raised to 280-330°C to decompose the ammonium sulfate into ammonia and ammonium hydrogen sulfate; In one embodiment, at least a portion of the ammonia gas generated in the ammonium sulfate decomposition section is returned to the sodium bicarbonate generation section; In one embodiment, at least a portion of the ammonium bisulfate generated in the ammonium sulfate decomposition section is returned to the ammonium sulfate generation section.
[0024] In one embodiment, the resource recovery method further includes calcining the generated sodium bicarbonate after the sodium bicarbonate generation stage to obtain sodium carbonate.
[0025] In one embodiment, the above-mentioned calcination uses natural gas produced by the gas field as energy to achieve low-cost operation and stable energy supply.
[0026] In one embodiment, the obtained sodium carbonate can be returned to the pH adjustment step of the pretreatment section.
[0027] On the other hand, this application provides a resource-based treatment system for high-mineralization gas field water, which includes, in order from upstream to downstream, a pretreatment unit, a mother liquor generation unit, a sodium bicarbonate generation unit, an ammonium chloride generation unit, an ammonium sulfate generation unit, and an ammonium sulfate decomposition unit. The pretreatment unit is configured to remove impurities from the gas field water; The mother liquor generation unit is configured to evaporate pretreated gas field water to generate a mother liquor containing a saturated sodium chloride aqueous solution. The sodium bicarbonate generating unit is configured to introduce ammonia gas into the mother liquor to saturate the amount of dissolved ammonia gas in the mother liquor; and to continue introducing carbon dioxide into the mother liquor to precipitate sodium bicarbonate solid and filter to obtain sodium bicarbonate. The ammonium chloride generation unit is configured to cool the mother liquor from which the sodium bicarbonate solid has been removed to below 10°C to precipitate ammonium chloride solid and filter to obtain ammonium chloride. The ammonium sulfate generating unit is configured to introduce ammonium bisulfate to react with the ammonium chloride generated by the ammonium chloride generating unit to generate ammonium sulfate and hydrogen chloride; The ammonium sulfate decomposition unit is configured to decompose ammonium sulfate to generate ammonia and ammonium hydrogen sulfate.
[0028] In one embodiment, the ammonium sulfate decomposition unit is further configured to be in fluid communication with the sodium bicarbonate generation unit to return at least a portion of the generated ammonia gas to the sodium bicarbonate generation unit.
[0029] In one embodiment, the ammonium sulfate decomposition unit is further configured to be in fluid communication with the ammonium sulfate generation unit to return at least a portion of the generated ammonium bisulfate to the ammonium sulfate generation unit.
[0030] This application enables the treatment and disposal of produced water from oil and gas fields to achieve true "zero discharge," avoiding the environmental pollution risks caused by external discharge and reinjection.
[0031] The resource-based treatment method and system for high-mineralization gas field water in this application not only provides ideas for the treatment of high-mineralization gas field water and the disposal of waste salt after evaporation, but also effectively converts sodium chloride industrial salt into sodium bicarbonate and soda ash, which are widely used in multiple industrial fields and have important economic value, through a salt chemical treatment process, thereby realizing the high-value-added utilization of waste resources.
[0032] This application reduces greenhouse gas emissions and promotes environmental protection and sustainability in the production process by collecting tail gas from gas field processing plants and producing carbon dioxide for reuse in the production of sodium bicarbonate and soda ash.
[0033] This application further processes the tail liquid generated during the production of sodium bicarbonate and soda ash to extract ammonia and hydrochloric acid, allowing these products to be recycled back into the sodium bicarbonate and soda ash production process. This achieves the recycling of raw materials, reduces production costs, improves the resource efficiency of the entire resource-based treatment method, and yields good social and economic benefits.
[0034] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description
[0035] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.
[0036] Figure 1 This is a schematic flowchart illustrating a method for the resource utilization of highly salinized gas field water, provided as an embodiment of this application. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application are described in detail below. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be arbitrarily combined with each other.
[0038] This application provides a method for the water resource treatment of a high-salinity gas field, including a pretreatment section, a mother liquor generation section, a sodium bicarbonate generation section, an ammonium chloride generation section, an ammonium sulfate generation section, and an ammonium sulfate decomposition section.
[0039] This application also provides a resource-based treatment system for high-mineralization gas field water, which includes, in order from upstream to downstream, a pretreatment unit 100, a mother liquor generation unit 200, a sodium bicarbonate generation unit 300, an ammonium chloride generation unit 400, an ammonium sulfate generation unit 500, and an ammonium sulfate decomposition unit 600.
[0040] Figure 1 A schematic flowchart illustrating a method for the resource recovery of highly salinized gas field water, provided as an embodiment of this application, is shown below. Figure 1 This application describes the process of resource recovery treatment of highly salinized gas field water.
[0041] (1) The gas field water generated during the oil and gas field development process is introduced into the pretreatment unit 100 for pretreatment. The gas field water liquid can be introduced into the regulating homogenizing tank and the residence time is about 4 to 8 hours. The effluent enters the oil removal and suspended solids removal step and the residence time is 2 to 3 hours. The effluent reaches the oil content ≤30mg / L and the suspended solids content ≤30mg / L. The effluent enters the hardness removal step and the hardness of the effluent is ≤100mg / L (calculated as calcium carbonate). The pH of the effluent is adjusted to 3.0-4.0 with hydrochloric acid and enters the Fenton oxidation catalytic oxidation step to remove most of the organic pollutants. Sodium carbonate is added to the effluent to neutralize the pH to 6.5-7.0. The effluent enters the filter to further remove impurities such as oil and suspended solids.
[0042] (2) After the pretreatment section, the gas field water has removed most of the impurities and enters the mother liquor generation unit 200 to generate mother liquor. The gas field water is thermally concentrated by multi-effect evaporation, and 3-4 effects of evaporation are carried out. Each stage of evaporation forms condensate, and the concentrated brine enters the next stage. The condensate is collected and enters the biological treatment device, and after treatment, it is used for industrial reuse.
[0043] (3) The mother liquor containing sodium chloride brine enters the downstream sodium bicarbonate generation unit 300 for sodium bicarbonate generation. Ammonia gas is introduced into the mother liquor at 30-40°C until the amount of dissolved ammonia gas in the solution reaches saturation. Then, carbon dioxide is introduced into the solution to obtain sodium bicarbonate solid precipitate (NaCl+NH3+H2O+CO2=NaHCO3↓+NH4Cl).
[0044] Furthermore, the sodium bicarbonate solid precipitate can be filtered, washed, dried, and calcined to obtain sodium carbonate asphalt. .
[0045] (4) The mother liquor from which sodium bicarbonate precipitate is removed enters the downstream ammonium chloride generation unit 400 for ammonium chloride generation. The mother liquor is cooled down, and taking advantage of the fact that the solubility of ammonium chloride is less than that of sodium chloride below 10°C, the ammonium chloride is separated from the mother liquor and filtered to obtain ammonium chloride. The mother liquor from which ammonium chloride is removed can be returned to the pretreatment unit 100 and mixed with the gas field water to be treated for further treatment.
[0046] (5) Add ammonium bisulfate to the ammonium sulfate generating unit 500, heat the ammonium bisulfate to the melting point of 147°C to melt it, and introduce the ammonium chloride generated in the ammonium chloride generating unit 400 into the ammonium sulfate generating unit 500 for ammonium sulfate generating section operation to generate ammonium sulfate and hydrogen chloride gas (NH4Cl+NH4HSO4=(NH4)2SO4+HCl), and heat to 140-160°C to release hydrogen chloride gas.
[0047] (6) In the ammonium sulfate decomposition unit 600, after the hydrogen chloride gas is released, the temperature is raised to 280-330℃ to decompose the ammonium sulfate into ammonia and ammonium bisulfate ((NH4)2SO4=NH4HSO4+NH3); the generated ammonia can be returned to the sodium bicarbonate generation unit 300 for recycling; the generated ammonium bisulfate can be returned to the ammonium sulfate generation unit 500 for recycling.
[0048] In one embodiment, the resource recovery system further includes a sodium carbonate generating unit connected to the sodium bicarbonate generating unit, the sodium carbonate generating unit being configured to calcine the sodium bicarbonate generated by the sodium bicarbonate generating unit to obtain sodium carbonate.
[0049] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. A method for the resource-based treatment of high-mineralization gas field water, characterized in that, It includes a pretreatment section, a mother liquor generation section, a sodium bicarbonate generation section, an ammonium chloride generation section, an ammonium sulfate generation section, and an ammonium sulfate decomposition section; The pretreatment section includes removing impurities from the gas field water; The mother liquor generation section includes evaporating pretreated gas field water to generate a mother liquor containing a saturated sodium chloride aqueous solution. The sodium bicarbonate generation section includes introducing ammonia gas into the mother liquor to saturate the amount of dissolved ammonia gas in the mother liquor; and continuing to introduce carbon dioxide into the mother liquor to precipitate sodium bicarbonate solid from the mother liquor and filter to obtain sodium bicarbonate. The ammonium chloride generation section includes cooling the mother liquor from which the sodium bicarbonate solid has been removed to below 10°C to precipitate ammonium chloride solid and then filtering it to obtain ammonium chloride. The ammonium sulfate generation section includes introducing ammonium bisulfate to react with the ammonium chloride generated in the ammonium chloride generation section to produce ammonium sulfate and hydrogen chloride; The ammonium sulfate decomposition section includes the decomposition of ammonium sulfate to generate ammonia and ammonium hydrogen sulfate.
2. The resource recovery method according to claim 1, characterized in that, The pretreatment section includes one or more of the following steps: homogenization, oil removal, suspended solids removal, hardness reduction, pH adjustment, oxidation treatment, and filtration; optionally, the oxidation treatment includes oxidation by any one of the following methods: Fenton process, electrocatalytic process, and ozone oxidation process.
3. The resource recovery method according to claim 1, characterized in that, In the sodium bicarbonate generation section, the reaction temperature after introducing carbon dioxide is 32-38℃.
4. The resource recovery method according to claim 1, characterized in that, The ammonium sulfate generation section includes heating ammonium bisulfate to its melting point, adding ammonium chloride generated in the ammonium chloride generation section under stirring, generating ammonium sulfate and hydrogen chloride at 140-160°C, and releasing hydrogen chloride gas; Optionally, the discharged hydrogen chloride can be converted into hydrochloric acid and returned to the pH adjustment step of the pretreatment section.
5. The resource recovery method according to any one of claims 1-4, characterized in that, The resource recovery method further includes returning at least a portion of the mother liquor remaining after removing solid ammonium chloride in the ammonium chloride generation section to the pretreatment section.
6. The resource recovery method according to any one of claims 1-4, characterized in that, In the ammonium sulfate decomposition section, the temperature is raised to 280-330℃ to decompose ammonium sulfate into ammonia and ammonium hydrogen sulfate; Optionally, at least a portion of the generated ammonia gas is returned to the sodium bicarbonate generation section; Optionally, at least a portion of the generated ammonium bisulfate is returned to the ammonium sulfate generation section.
7. The resource recovery method according to any one of claims 1-4, characterized in that, The resource recovery method further includes calcining the generated sodium bicarbonate after the sodium bicarbonate generation section to obtain sodium carbonate. Optionally, the obtained sodium carbonate is returned to the pH adjustment step of the pretreatment section.
8. A resource-based treatment system for high-mineralization gas field water, characterized in that, The units, arranged from upstream to downstream, include a pretreatment unit, a mother liquor generation unit, a sodium bicarbonate generation unit, an ammonium chloride generation unit, an ammonium sulfate generation unit, and an ammonium sulfate decomposition unit. The pretreatment unit is configured to remove impurities from the gas field water; The mother liquor generation unit is configured to evaporate pretreated gas field water to generate a mother liquor containing a saturated sodium chloride aqueous solution. The sodium bicarbonate generating unit is configured to introduce ammonia into the mother liquor to saturate the amount of dissolved ammonia in the mother liquor. Carbon dioxide is then introduced into the mother liquor to precipitate sodium bicarbonate solid, which is then filtered to obtain sodium bicarbonate. The ammonium chloride generation unit is configured to cool the mother liquor from which the sodium bicarbonate solid has been removed to below 10°C to precipitate ammonium chloride solid and filter to obtain ammonium chloride. The ammonium sulfate generating unit is configured to introduce ammonium bisulfate to react with the ammonium chloride generated by the ammonium chloride generating unit to generate ammonium sulfate and hydrogen chloride; The ammonium sulfate decomposition unit is configured to decompose ammonium sulfate to generate ammonia and ammonium hydrogen sulfate.
9. The resource recovery system according to claim 8, characterized in that, The ammonium sulfate decomposition unit is also configured to be in fluid communication with the sodium bicarbonate generation unit so as to return at least a portion of the generated ammonia gas to the sodium bicarbonate generation unit.
10. The resource recovery system according to claim 8 or 9, characterized in that, The ammonium sulfate decomposition unit is also configured to be in fluid communication with the ammonium sulfate generation unit to return at least a portion of the generated ammonium bisulfate to the ammonium sulfate generation unit.