Working condition description: Filtration system of oilfield reinjection waterIt is a measure that water is injected into reservoir through injection well to maintain reservoir pressure and improve oil recovery rate and recovery factor. Equipment Description: In Daqing Oilfield, Zhengyuan has successfully reduced the suspended solids, oil and particles in reinjection water to 1:1:1 standard, which is the highest standard achieved in China without using ultrafiltration.The biggest advantage of this scheme is the high economic automatic filtering system. Description of filtration process: The filter adopts multi-stage filtration, and the filtered water can be used for reinjection and discharge. The first stage filtration adopts automatic backwash filter to reduce the suspended solids and solid particles in the liquid to less than 1 micron. The second stage is used to separate the liquid. The three-stage filtration adopts biochemical device to separate the dissolved oil from the liquid. The fourth stage filtration adopts ultrafiltration device, which can recycle the liquid.