How to treat oil field produced waste water?

First, the main source of oilfield wastewater

A large amount of wastewater will be produced in the process of oilfield exploitation, especially in large-scale oilfield exploitation, and the water content of produced liquid is relatively higher. Oilfield mining wastewater mainly comes from:

(1) After the water-bearing crude oil is mined out, the wastewater separated by the three-phase separator is the produced water;

(2) backwash the water injection well regularly to clean the washing water;

(3) Cleaning water generated by regular cleaning of oil storage tanks;

(4) Backwashing water generated after backwashing the pressure filter tank in the wastewater treatment station;

(5) Condensing wastewater in the station;

(6) Construction waste liquid, including drilling mud, fracturing fluid, acidizing residue, etc.

Second, the characteristics of oilfield mining wastewater

Oilfield wastewater is a complex liquid mixture, its main components are water, crude oil, soluble gas, solid suspended matter, electrolyte, bacteria and various oilfield chemical additives and other substances, direct discharge, not only will cause serious harm to the environment, pollution of surface water and farmland, resulting in the death of animals and plants and human potential diseases, to the local people’s lives caused serious harm.

Moreover, acid gas or salt in oilfield wastewater will accelerate the corrosion of pipeline equipment; The solid suspended solids in oilfield wastewater will clog the formation. Industrial bacteria in oilfield wastewater will corrode pipelines, clog pipelines, and deteriorate water quality.

Oilfield wastewater generally has the following characteristics:

1, high salinity, accelerate the corrosion rate, but also to the biochemical treatment of wastewater caused difficulties;

2, the oil content is high, much higher than the water quality standards required by various outlets

3, containing a large number of microorganisms, bacterial proliferation not only corrodes the pipeline but also causes serious blockage of the formation;

4, contains a large number of scale ions, produced water contains SO42-, CO32-, Ca2+, Mg2+, Ba2+ and other scale ions;

5, suspended matter (polymer injection area) content is high, fine particles, easy to cause formation blockage.

Third, how to treat the wastewater produced in the oil field

When the oil field is developed, there will be a lot of produced water, which is a high concentration of sewage, so how do we deal with it? First of all, what we have to do is to study the production water treatment process of the oil field, with the technical process, we can effectively treat the oil field produced water.

So, have you ever wondered what the oilfield produced water treatment process is like? The research we have done in this area naturally needs to be applied out, and we will introduce it to you first.

1. Water stability and purification

The produced water of oil field has the characteristics of “high salinity, high chloride ion, high hydrogen sulfide, high water temperature, low pH”. This type of produced water generally has poor reaction power, poor flocculation effect, and difficult to purify and stabilize water quality. The high salinity of water greatly accelerates the reaction of the galvanic cell in water, which speeds up the corrosion rate of equipment and pipes.

In view of the physical properties of the produced water, in order to solve the problems of high salinity and easy corrosion, easy scaling, and poor water purification effect, the produced water treatment adopts the whole system pressure treatment process, and adopts the micro positive pressure natural gas sealing process to seal the treatment equipment and other container facilities for oxygen isolation. A new type of pressure produced water purification equipment is developed to improve the reaction effect of the agent. Avoid the “four high and low” water type because of the strong corrosion problem brought by dissolved oxygen.

2. Research on efficient produced water treatment equipment

Domestic pressure coalerization deoiling equipment usually uses scattered packing or structured packing, and the filling method is a section of coalerization structure. This type of equipment is easy to plug, the coalerization separation efficiency is low, and the single processing capacity can only reach 250 m³/h. According to the project owner’s requirements for large-scale equipment, we developed an efficient pressure coalescent-deoiling equipment, and adopted a segmented coalescent-deoiling filler structure, which effectively solved the problems of coalescent-filling plugging and low removal rate, and the processing capacity of a single unit reached 350 m³/h.

3. Processing technology

In view of the technical problems such as poor treatment and purification effect, serious corrosion and serious scaling of desulfurization tower, the produced water with “four high and low” characteristics in oilfield is studied. The whole system pressure closed treatment process is selected to effectively reduce the strong corrosion hazards caused by dissolved oxygen in high sulfur and high salinity produced water; The quality control and gas removal desulfurization technology of produced sewage can ensure the desulfurization treatment effect and solve the scaling problem of equipment in the condition of gas removal desulfurization. A new type of pressure coalescation oil removal and coagulation sedimentation equipment has been developed and designed, with a single processing capacity of 350 m³/h, ensuring the stable operation of the produced water treatment system and the water quality standards.

As you can see, for the treatment of oil field produced water, our process is still quite mature, which is also the research results of our efforts, of course, the most hope is that it can be applied in practical projects.

Fourth, what are the oilfield sewage treatment agents?

There are many kinds of oilfield sewage treatment agents, reverse phase demulsifier, flocculant, crude oil demulsifier and so on. The composition of oilfield wastewater is complicated, the oil content and the existence form of oil in water are different, and in most cases, it is often mixed with other wastewater, so a single treatment method is often ineffective. At the same time, because of the limitations of various methods, in practical applications, it is usually two or three methods combined to make the effluent water quality meet the discharge standard. Oilfield sewage treatment agents are mainly demulsification and removal of dispersed oil, and deep treatment includes ultrafiltration, activated carbon adsorption, biochemical treatment, etc., mainly to remove dissolved oil.

Compared with the physical treatment technology, the effect of chemical treatment technology on oilfield sewage can be more thorough, the so-called chemical treatment technology is for the relevant components of oilfield sewage, the use of oilfield sewage treatment agent into the oilfield sewage, so that the organic matter and inorganic matter chemical reaction to form a relatively stable non-toxic or slightly toxic substances and then separated from the oilfield sewage; The usual chemical treatment technology uses chemical flocculation method, adding the oil field sewage treatment agent to the oil field sewage, stirring it evenly, through air floating and other ways, making it bridge or neutralize the suspended matter and colloid in the sewage to form a flocculant, and then remove the flocculant, so as to achieve the effect of oil field sewage treatment.

The use of oilfield sewage treatment agent, the whole process is easy and convenient for the treatment of oilfield sewage, chemical treatment technology operation is very simple, the effect is remarkable, is currently more common and fast and efficient oilfield sewage treatment agent.