The oil production wastewater produced by the oilfield during the production operation contains a large amount of emulsified oil and dissolved oil. In addition, the solid suspended particles in the oil production wastewater and various lignin, barite powder, clay and other substances added during the oil production operation make the oil production wastewater The ingredients are very complex. The oil production wastewater in the oil field must be strictly treated before it can be discharged or reused. But the actual oil extraction wastewater treatment is very difficult. In our country, the usual wastewater treatment methods include physical method, chemical method, physical chemical method and biological method. The above methods have their own advantages in technology and economy. There are great differences in the quality and quantity of oil production wastewater from different oilfields. Therefore, choosing a reasonable wastewater treatment method in combination with the actual situation of oilfield oil production wastewater can effectively improve the efficiency of oil production wastewater treatment.
Water quality characteristics of oil extraction wastewater
The main components in the wastewater produced in the process of oil production in the oil field are crude oil and a small amount of organic substances as oil production aids. Under normal circumstances, the specific characteristics of the water quality of oil production wastewater are as follows: the oil production wastewater contains a large amount of paraffins between 14 and 18, and the content of five-ring and six-ring naphthenic compounds is also relatively large. Most of them show that the distribution of carbon molecules is wide, the change of carbon number is very complex, and most of the total molecules are distributed in the range of 100-150, which exceeds 70% of the total amount of organic molecules; in addition, wastewater also contains a large amount of Most of these chemicals are added in the process of drilling or crude oil treatment, and it is difficult to achieve degradation. In addition, the oil production wastewater has a large salt content and high temperature.
Status Quo of Oil Production Wastewater Treatment
The conventional oil production wastewater treatment process in oilfields is basically three steps of "oil separation - flotation - filtration". The main purpose of this process is to remove a small amount of crude oil and solid suspended particles in the oil production wastewater. This technology has been widely used in the field of oil extraction wastewater treatment in my country's oilfields, and the actual treatment effect of this process in the actual point of wastewater treatment is also relatively obvious. The oil production wastewater treated by the above process can basically meet the water quality requirements of oilfield wastewater reinjection. However, under the premise of the continuous development of modern oil fields and the continuous increase of production and extraction, there are still some problems in the process of oil production wastewater treatment.
Problems facing oil extraction wastewater treatment
With the development of oilfields, the three-stage oil recovery has been widely used in oilfield oil production operations. Among them, the application of polymer flooding has caused a sharp increase in the viscosity of oil well produced water, such as the properties of emulsified oil are also more stable, and a large number of surfactants have been used. The beads have serious emulsification phenomenon, and it is difficult for some tiny oil beads to aggregate, which directly increases the difficulty of oil-water separation. With the gradual increase of water content of oil wells in modern oilfields, the total amount of oil production wastewater is also increasing. Therefore, some oil production wastewater must be discharged into the natural environment. Therefore, oil production wastewater treatment must meet the discharge standards. However, the treatment of oil production wastewater in some heavy oil fields is more difficult. It can be seen that the treatment of oil production wastewater in the oil field will be the key research task of the oil field in the future.