Research Of New Process And Matching Technology For Oily Sewage Disposal In Oil Field

The state of the art of the development of hydrocyclone and its application on oilfield oily sewage treatment is introduced in this paper. At present, gravity settlement devices, such as free water knock out devices, are normally adopted in China's oilfields. This kind of device has the drawback of lower treatment efficiency. Recently, many production plants and research institutions have begun dealing the research work relating to new separation technologies, e.g., hydrocyclonic separation, floatation, and membrane separation. After several years' collaborations with actual application, the research on matching techniques, such as boosting manners, coalescence, and filtration, has gained progress to some extent. But it is not enough, and needs to be deepened.Starts with improve and optimize hydrocyclones' structure; a type of reverse-whirl double-inlets structure was designed. Its cone segment adopts curve transition. The vortex cavity's length is 65 mm. It is found that it has higher separation efficiency than other normal used hydrocyclones.Different types of pumps were tested because the pumping process is an important part in the matching technology program. Contrast tests of hydrocyclones' separation performance when using different types of pumps were carried out. Droplet diameter distribution around the pumps was analyzed. It shows that the low-cut cavity type pump, e.g., single screw pump, can be used to reduce the effect of droplet break up; and, the low rotate speed centrifugal pump can reduce the emulsification effect on droplets, which is then beneficial to the hydrocyclonic separation.At the aspect of new technology program for oily water treatment, four types of matching technology programs including 'one stage hydrocyclone plus a filter' and so on were formed by using hydrocyclones, floatation, and filter. During oilfield tests, combined with the economic benefit analysis, two types of high efficient hydrocyclonic matching technology programs were finally determined to be used for oilfield application and popularization.Tests show that by using 'one stage hydrocyclone plus a filter' 1000 mg/L oily water can be treated to less than 10 mg/L, which fulfills the water re-injection requirement of mid-lower permeable bed; by using 'two stages hydrocyclones in serious' the same inlet oily water can be treated to less than 30 mg/L, which fulfills the requirement of mid-higher permeable bed.