The downhole environment is much harsher and more complex than the surface environment, such as high temperature, high pressure, high corrosiveness, etc. Due to the structure and function of the downhole tools, they need to work for a long time in the well, so they must have good sealing ability. Traditional single seals have limitations in such a complex environment, while combination seals can solve this problem by complementing the advantages of several seals.

Combination seal is a seal assembly that consists of several single sealing parts combined together to complete the sealing function. It is widely used in downhole tools, such as positioning seal, insertion seal, expansion joint, slip-on and many other downhole tools. At present, the common form of seal combination in downhole tools is Vee packing, which mainly consists of 3 parts: support ring, V-shaped seal ring and pressure ring. As shown in the figure.

The use of multiple seals in combination is more reliable. The downhole high-pressure fluid passes through multiple V-rings, and the pressure will be gradually reduced until it is lost, and the pressed multiple V-rings can seal the differential pressure of 40Mpa or higher. Therefore, this seal form has good sealing performance in various different pressure working conditions.

What should be noted when choosing a Vee Packing?

1. Design requirements

In order to ensure the sealing effect, the number of sealing rings is 6-12pcs in general, the higher the sealing pressure, the more the number of V-rings.

2. Material selection of seals

Commonly used V-ring materials are NBR, HNBR, FKM, and PTFE, PEEK for pressure ring and support ring. According to the different working conditions in the well, choose different materials.

3.Dimensional issues

In order to play a better sealing and supporting seal role, first need to know the exact size of the groove such as groove diameter, rod diameter, groove width, etc., and then by the technician according to the relevant standards to determine the design of the size of the Vee packing.