Permeability plugging tester is a special instrument for testing the permeability and plugging performance of drilling fluid. The plugging evaluation is carried out by using different specifications of porous sand pan media. It is mainly composed of frame body, high pressure filtrate receiver, drilling fluid cup and pressure device. The cup body is equipped with an experimental cup cover, a floating piston and a scribed bottom cover. The cup body has a groove deeper than the standard cup body to place the sand disc. The sand disc used has stable performance through strict production process control.

In the heating process, the instrument can perform filtration test without the interference of precipitated particles on the filter medium. Under the pressure interval, the plugging tester can demonstrate how the drilling fluid forms a low permeability cake to blocking loss, and can prevent differential pressure sticking. Generally, the differential pressure is much higher than that under high temperature and high pressure test. It can be used outdoors or in a laboratory environment.

Under certain pressure conditions, when drilling fluid penetrates into the wellbore, some solid materials enter the pores or crevice of the wellbore to deposit and form internal filter cake, which reduces the permeability near the wellbore; the other part of the solid material is blocked outside the wellbore to form external filter cake. The essence of physical plugging technology of drilling fluid is to reduce the invasion depth of filtrate through the joint action of internal filter cake and external filter cake, which is the same purpose as filtration reduction.