What is reflux? How did the reflux come out?

With the enhancement of human awareness of environmental protection, various environmental protection laws and regulations and environmental management systems are gradually improved, and the conditions for pollution prevention and control are getting higher and higher. Acidification is the main technology to solve the plugging problem of oil and water wells in oil fields. Hydrochloric acid and hydrofluoric acid in acidizing solution have different toxicity and strong corrosiveness. The properties of waste acid liquid discharged from acidizing, acid fracturing or pickling pipelines are related to the types of acid liquid, the properties of crude oil and the properties of formation fluid, which are usually characterized by high COD and high salinity. Waste acid solution is highly corrosive, and it will acidify the soil if it is discharged into the soil. The scaling of acidic solution and sulfide will produce toxic gas hydrogen sulfide. The preparation of acetic acid will produce very irritating steam, which will cause serious burns if it comes into direct contact with animals and plants. It is harmful to the environment and biology and has a certain impact, so it must be properly handled in accordance with relevant regulations. For example, the acidizing stimulation construction of offshore oil wells has limitations, and domestic and foreign oilfield downhole operations all hope to have a clean acidizing stimulation technology without backflow. In addition, conventional acidizing still has the following problems: 1, oil wells are easy to produce sand after acidizing; 2. Highly corrosive; 3. The residual liquid after acidification must be recovered by reverse drainage, which is a complicated process, and sometimes it will cause gathering and transportation accidents if it is not cleaned; 4. The recycling cost is high, it is not easy to operate, and incomplete treatment is easy to cause environmental problems. Cotton bio-acid is the first international patent technology owned by Shi Sheng Petroleum Technology, which successfully solved the above-mentioned problems in offshore oil fields. After acidizing construction, the construction fluid can enter the submarine pipeline flow without affecting the gathering and transportation system, with low corrosivity, and the treated reservoir does not destroy the rock skeleton, which has obvious reservoir protection characteristics. There is no need to recycle after construction, which saves the funds of offshore oil fields, avoids the danger of chemical transportation, stacking and storage, and meets the requirements of clean production, which is a blank in domestic oil field stimulation technology. If it is used in offshore oil fields, it can save 60 thousand yuan only by recovering transportation and treatment costs, which is a major breakthrough in environmental protection and production increase technology. As a technology to increase production and plug removal in formation without flowback, it can not only greatly increase oil well production, but also reduce acid flowback, so it is a clean production technology worth advocating. Completely solve the problem of pollutant discharge. Shi Sheng Petroleum Science and Technology adheres to the development strategy of specialization of petroleum service science and technology, constantly innovates, serves with leading technology, design and innovative ideas, and provides oilfield with new technologies for acidizing and increasing production required by complex environment. The conventional acidizing stimulation technology in oilfield is 1. Acidizing construction steps: well site preparation, wellhead equipment preparation, well killing, running construction string, liquid preparation, acid preparation and pump test. 2) Construction technology: replacing acid with low pressure, setting packer and injecting with high pressure pump. 3) Late stage of construction: blowoff and drainage, trial production and trial production of oil and gas wells. 2. Acidizing construction pollution link 1) Well killing process: pollution caused by blowout or overflow due to improper operation or improper selection of well killing fluid density. 2) Pipe string: liquid brought to the ground in the process of tripping the pipe string. 3) Blow-out drainage process: waste acid solution is easy to be discharged to the surrounding environment, causing pollution. 3. The main pollution sources in the acidification process of main pollutants are drainage and residual liquid discharged during trial production. The nature of residual acid is also related to the type of acid, crude oil and formation properties. At present, the commonly used strong acids are hydrochloric acid and hydrofluoric acid, and various acidification additives are added, such as retarder, corrosion inhibitor, iron stabilizer, anti-emulsifier, clay stabilizer, filter aid, mud slag inhibitor, wetting reversal agent and so on. The main pollutants are acids, various organics, heavy metals, various surfactants and crude oil. Some additives are highly toxic chemicals, such as quaternary ammonium products. 4. The properties of waste acid discharged from acidizing, acid fracturing or pickling pipelines are related to the acid type, crude oil properties and formation fluid properties, and usually show high COD and salinity. See table 1-4 for its properties. Waste acid solution is highly corrosive, and it will acidify the soil if it is discharged into the soil. The scaling of acidic solution and sulfide will produce toxic gas hydrogen sulfide. Acetic acid used to prepare acetic acid can produce strong irritating vapor, and direct contact with animals and plants will cause serious burns. 5. Measures to prevent pollution during acidizing operation 1) Acid solution should be completed at the acid distribution station to realize mechanized operation and closed operation to prevent environmental pollution caused by acid gas volatilization. 2) During acidizing construction of water wells, the undrained acid treatment process of water injection wells can be adopted to avoid the generation of residual acid. 3) During acidification, the acid solution should be kept by special personnel to prevent leakage and environmental pollution caused by human factors or other factors. 4) The acid container shall comply with relevant regulations to prevent acid from corroding the container, causing leakage and polluting the environment. 5) Recover and treat waste acid solution in time. The treatment of oilfield acidified wastewater must go through the processes of neutralization, coagulation, oxidation and filtration, and the treated water quality can meet the national comprehensive wastewater discharge standard.