Gas field sewage harmless treatment method

Abstract

The invention discloses a gas field sewage harmless treatment method comprising the following steps: water content in the gas field sewage is evaporated with a ventilation method, such that gas field sewage is turned harmless. With the method, defects of existing gas field sewage treatment methods are overcome; a gas field sewage harmless treatment problem can be effectively solved; a gas field sewage environment pollution problem can be effectively solved; gas production auxiliary agents and useful substances in the gas field sewage can be effectively recycled; cost and energy consumption for recycling the gas production auxiliary agents and useful substances in the gas field sewage can be greatly reduced; and gas field sewage transportation volume, transportation cost, treatment energy consumption and treatment cost can be greatly reduced. The method is safe and reliable, and has the advantages of easy implementation, wide application, easy popularization and the like. The method provides significant economic and social benefits.

Description

technical field [0001] The invention relates to a sewage treatment method. More specifically, it relates to a method for harmless treatment of gas field sewage. 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 sewage is often produced. These sewage are usually called "gas field sewage", sometimes referred to as For "sewage". [0003] At present, "gas field sewage" is generally divided into two categories in China: one is "gas field sewage" containing methanol, and the other is "gas field sewage" without methanol. [0004] The current domestic method of treating methanol-free "gas field sewage" is to reinject the "gas field sewage" into the formation. But there is following defective in this method: [0005] 1) The reinjection ...

AI Technical Summary

Problems solved by technology

[0008] 2) Before reinjection, the "gas field sewage" scattered throughout the gas field needs to be concentrated to the designated reinjection site, and the cost of transporting "gas field sewage" is relatively high

[0012] Take the Yanchang gas field as an example: although there are many gas gathering stations in this gas field, only one sewage treatment plant is built in order to reduce fixed investment; one gas gathering station in this gas field generally collects the natural gas produced by 5 to 10 gas wells, The average daily sewage production of a well is less than 0.2 tons per day, and the average daily water production of a gas gathering station is less than 2 tons per day. If pipelines are used to transport the sewage from the gas gathering station to the sewage treatment plant, a huge fixed investment is required; the gas field At present, tanker trucks are used to transport the sewage produced by the gas gathering station to the sewage treatment plant for centralized treatment; since the distance between the gas gathering station of the gas field and the sewage treatment plant is generally more than 50 kilometers, the distance between the farthest gas gathering station The transportation distance of the sewage treatment plant is more than 100 kilometers, so the method of transporting the sewage of the gas gathering station by car tanker requires a lot of cost and energy consumption

[0013] 3) Useful substances in "gas field sewage" cannot be recycled

[0015] 1) The "gas field sewage" after recovering methanol requires high cost when reinjected into the formation, which will cause serious environmental pollution hazards after reinjection into the formation

[0016] It can be seen from the known knowledge in this field: generally adopt rectification method to reclaim the methanol in "gas field sewage" at present; The energy consumption and recovery cost of methanol are very high; therefore, at present, the rectification method can only recover most of the methanol in the "gas field sewage", and the "gas field sewage" after methanol recovery still contains less than 3% of methanol; currently In China, methanol is generally not recovered from "gas field sewage" with a methanol content of less than 3%, and the "gas field sewage" with a methanol content of less than 3% is generally directly reinjected into the formation; currently, the average methanol content of 1 ton is reinjected The cost of "gas field sewage" below 3% generally exceeds 50 yuan / ton

[0017] Known knowledge in this field: Methanol is highly toxic and will be first decomposed into carcinogenic and highly toxic formaldehyde. The "gas field sewage" containing methanol will seriously pollute the environment if it enters the environment. Domestically, it is not allowed to directly dispose of methanol-containing gas field sewage. Discharged into the environment; methanol decomposes slowly in the formation, and methanol sewage will bring serious pollution hazards after re-injection into the formation

[0018] 2) The cost of transporting and concentrating methanol-containing "gas field sewage" is relatively high

[0019] It can be seen from the known knowledge in this field that at present, the methanol-containing "gas field sewage" is generally transported 20 to 200 kilometers by tank truck to the sewage treatment plant station for concentration, and then the methanol recovery device installed at the treatment plant station is used to recover the methanol in the "gas field sewage". Methanol, for which the average transportation cost is 50 yuan / ton

[0020] 3) The energy consumption and cost of recovering methanol from "gas field sewage" are relatively high

[0021] 4) Useful substances in "gas field sewage" cannot be recycled

Since "addition, subtraction and regeneration" is a relatively complicated industrial step (or process), it needs special equipment, facilities, "alkaline substances" and related investment and operating costs to complete, so it will inevitably lead to the final regeneration of "production sewage" into "inhibition" The cost and expense of "icing agent liquid" are relatively high, and the cost and expense of harmless treatment of gas field sewage containing deicing agent are relatively high

[0029] It can be seen from the known knowledge in this field that there is no public information and successful precedents in China for the harmless treatment of gas field sewage containing deicing agents by ventilation (or wind and sun) without adding alkali

[0030] 3) The technical solution described in this invention does not involve or specify the method of directly regenerating "production sewage" (ie, gas field sewage) into "deicing agent liquid" in the gas gathering station (or near the gas gathering station), so it does not involve, Indicate the method of harmless treatment of "production sewage" containing deicing agent directly in the gas gathering station (or near the gas gathering station)

[0032] Known knowledge in this field: At present, the sewage containing deicing agent is generally transported to natural gas purification treatment plant or sewage treatment plant for centralized treatment; thus resulting in a substantial increase in the cost of recycling deicing agent

[0033] Take Yanchang gas field as an example: the concentration of deicing agent in the gas field sewage separated by the gas gathering station of this gas field can reach 1wt% at least; Known knowledge in this field, in order to reduce dosing cost and dosing amount, to gas well (or The higher the concentration of the deicing agent liquid added in the gas-gathering pipeline), the better, and the concentration of deicing agent is generally not less than 20wt%. Based on this, further calculation shows that: in order to recycle 1 ton of deicing agent from the sewage of the gas-gathering station 20wt% deicing agent liquid needs to be transported 50-100 kilometers to the sewage treatment plant with 20 tons of gas field sewage by car tanker. For this reason, it needs to be transported twice by 10-ton tanker for a round trip of 200-400 kilometers, which requires a lot of freight and energy consumption

[0034] 4)) The technical scheme described in this invention does not specify specific methods for recycling corrosion inhibitors, drainage agents, scale inhibitors, sand washing agents, and well killing fluids from gas field sewage, nor does it involve the use of gas-gathering stations (or gas-gathering method of recycling corrosion inhibitors, drainage agents, scale inhibitors, foaming agents, sand washing agents, and well killing fluids directly from gas field sewage

[0035] According to the known knowledge in this field: in the natural gas production process, corrosion inhibitors, drainage agents, and scale inhibitors are usually added to gas wells (or gas-gathering pipelines). When the liquid is separated, most of it enters the separated gas field sewage; however, at present, there is no successful precedent for recycling corrosion inhibitors, drainage agents, and scale inhibitors from gas field sewage in China, and there is no such thing in the gas gathering station (or gas gathering station) Nearby) a successful precedent of directly recycling corrosion inhibitors, drainage agents, and scale inhibitors from gas field sewage

[0036] According to the known knowledge in this field, in the process of natural gas production, in order to carry out downhole operations of gas wells, well killing fluids are usually added to the gas wells, and then the sewage formed by these well killing fluids is discharged from the wellhead to the surface environment, or these The killing fluid is separated into gas field sewage by the separation equipment of the gas gathering station; however, there is no successful precedent for domestic gas fields to recycle the killing fluid from the gas field sewage, and there is no direct recycling of the killing fluid from the gas field sewage in the gas gathering station (or near the gas gathering station). Successful precedent of recovery and utilization of killing fluid in China

[0037] Known knowledge in this field: in the natural gas production process, in order to discharge the silt in the wellbore of the gas well, the sandwashing agent (or antifreeze sandwashing agent) and water preparation sandwashing agent (or antifreeze flushing agent) are usually added to the gas well. sand liquid), and then discharge the sewage formed by these sand washing liquids (or antifreeze sand washing liquid) from the wellhead to the surface environment, or separate these sand washing liquids (or antifreeze sand washing liquid) through the separation equipment of the gas gathering station However, at present, there is no successful precedent for domestic gas fields to recycle sand washing agent (or antifreeze sand washing agent) from gas field sewage, and there is no direct recycling from gas field sewage in the gas gathering station (or near the gas gathering station) Successful precedent of sand washing agent (or antifreeze sand washing agent)

[0038] 5) The technical solution described in this invention does not involve the method of recycling solid deicing agent, deicing agent solid-liquid mixture or solid medicament column from gas field sewage containing deicing agent

[0039] 6) The technical solution described in this invention does not involve the method of using ventilation and heating in combination to recover and utilize deicing agent liquid from gas field sewage containing deicing agent

[0042] 7) The technical solution described in this invention does not involve the method of using solar heating (or sunlight) to recycle the deicing agent liquid from the "production sewage" containing the deicing agent, nor does it involve the combined use of ventilation and solar heating (or The method of recycling deicing agent liquid from the "production sewage" (ie, gas field sewage) containing deicing agent by means of solarization)

[0049] It can be seen from the known knowledge that water-soluble polymer liquids (such as polyvinylpyrrolidone aqueous solution) are often used as hydrate inhibitors in gas fields, and such water-soluble polymer liquids usually enter gas field sewage; at present, water-soluble polymer liquids are not recycled from gas field sewage in China. Published precedents and publicly available information on polymer liquids