Gas field produced wastewater reduction and harmless treatment methods

Abstract

The invention discloses gas field produced wastewater reduction and harmless treatment methods. According to the methods, water is separated from gas field produced wastewater with a desalting process, concentrated gas field produced water is formed, and the volume of the gas field produced water is reduced; meanwhile, the invention also discloses a further concentrated gas field produced wastewater harmless treatment method. With the adoption of the treatment method, defects in existing gas field produced wastewater treatment methods are overcome, the problem of harmless treatment on the gas field produced wastewater can be effectively solved, the problem of pollution environment caused by the gas field produced wastewater can be effectively solved, gas production aids and useful substances in the gas field produced wastewater can be effectively recovered, the cost and the energy consumption for recovery of the gas production aids and useful substances from the gas field produced wastewater can be greatly reduced, and the transportation volume, the transportation cost and the treatment energy consumption and expense of the gas field produced wastewater can be greatly reduced; the method has the advantages of being easy to implement, safe, reliable, wide in application, easy to popularize and the like; the economic benefit and the environmental protection benefit are remarkable.

Description

technical field [0001] The invention relates to a method for treating natural gas produced water. More specifically, it relates to a gas field production water reduction and harmless treatment method. Background technique [0002] Natural gas is generally obtained through the development and production of gas fields or gas wells (referred to as natural gas exploitation or natural gas production). During the development and production of gas fields or natural gas exploitation, a large amount of produced water is often produced. These produced water are usually called "gas field produced water". , sometimes simply referred to as "produced water", commonly known as "gas field sewage" or "sewage". [0003] At present, domestic gas field produced water is usually divided into two categories: one is gas field produced water containing methanol, and the other is gas field produced water without methanol. [0004] It can be seen from the known knowledge in the art that there is a ...

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Problems solved by technology

The reinjection of produced water in gas fields is a technical solution that has to be adopted, and the reinjection of produced water in oil fields is a technical solution that is actively adopted; oil layers need water injection to supplement energy, and water injection into oil layers can increase the oil production capacity of oil layers. The produced water is all injected into the oil layer, and it is generally not enough. It is often necessary to supplement and inject a large amount of external water into the oil layer. Therefore, the produced water of all domestic gas fields is not injected into the gas layer, but into other deep formations that do not produce gas, and various methods are used to prevent it from entering the gas layer

Due to the high salinity of gas field produced water and generally containing a large amount of chemical agents or toxic substances, the produced water from gas fields is not allowed to be injected into shallow formations, and is generally injected into formation rocks with a depth of more than 2,000 meters; due to the porosity of formation rocks at this depth It is very small (generally no more than 10%), and the ability to accept the produced water of the gas field is extremely limited, so it is necessary to invest a huge amount of money to drill and build many water injection wells to solve the problem of reinjection of the produced water in the gas field; therefore, for the gas reservoir, the produced water only needs to No entry is allowed; at present, the reinjection of produced water in various domestic gas fields is extremely difficult, which has seriously affected the development and production of gas fields

[0008] 2) Before the gas field produced water is reinjected, it is necessary to concentrate the gas field produced water scattered throughout the gas field to the designated reinjection site, and the cost of transporting and concentrating the gas field produced water is relatively high

[0010] 3) The useful substances in the produced water of the gas field cannot be recycled

[0013] 1) Reinjection of gas field produced water after recovering methanol requires high costs, and serious environmental pollution risks will be generated after reinjection into the formation

[0014] 2) The gas field produced water after recovering methanol still contains a small amount of methanol, which makes it more difficult to re-inject into the formation, and the cost of re-injection is higher

[0016] 3) The cost of transporting and concentrating produced water from methanol-containing gas fields is relatively high

[0018] 4) The energy consumption and cost of recovering methanol from gas field produced water are relatively high

[0019] 5) Cannot recycle the useful substances in the produced water of the gas field

[0025] Taking Dongsheng Gas Field as an example, the lowest ambient temperature in winter is -31°C, and the average temperature in most of the time from mid-December to early February is lower than -20°C, so the ventilation evaporation in winter is extremely low; The output water can reach 80 tons / day, and the produced water of some gas gathering stations can reach more than 100 tons / day; if it is evaporated by heating, the energy consumption required is extremely huge

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