In the field of oil and gas field development, typical
wellhead devices are key equipment ensuring safe and efficient oil and gas extraction. Take the KQ78-105 wellhead device as an example, which is mainly used for extracting oil and natural gas from ultra-high pressure, high sulfur-resistant oil and gas wells. It was first applied in the Tarim Oilfield in 2013. Its hanger can seal and suspend the tubing string; the shear
safety valve in the main channel of the Christmas tree can shear steel wire ropes and armored cables; other gate valves and safety valves can cut off and seal pipelines; and the end throttle valve is used to control and adjust wellhead pressure and flow.
Generally, gas production wellhead devices need to comply with API Spec 6A and GB/T22513-2013 standards and have the right to use the API monogram. They are suitable for the extraction of various directional wells and horizontal wells under different working conditions. The universal straight-hole design of the tubing head facilitates the installation of tubing hangers of various specifications, and a full set of jackscrew assemblies can be designed to fix the anti-wear sleeve and hanger. The 45° shoulder of the straight-hole design has a large bearing capacity; the side outlet of the studded flange is equipped with a VR plug, allowing for pressure replacement of the side wing valve. The BT-type or P-type secondary sealing mechanism at the bottom can be installed by cutting the casing on site to adapt to the height of the sealing device, and the test joints and grease injection joints all adopt metal-to-metal sealing.
In terms of daily water supply, water well heads also have typical characteristics. For example, the Song Dynasty "Dajie Ancestral Well" found in Quangang District has a wellhead made of 7 vertical granite strips, forming an irregular heptagon, 0.51 meters high, slightly tapering inward from bottom to top. The outer sides of the stone strips are flat, and the inner sides are rough, a unique wellhead shape rarely seen in China's well history.
Manhole heads on urban underground pipelines are also representative. Manholes can be divided into drainage manholes, water supply manholes, cable manholes, communication manholes, gas manholes, etc. Their wellhead shapes are generally square and circular; circular manholes are mostly used, and square manholes are used when the pipe diameter is large and there are many branch pipes. In terms of material, there are brick manholes, plastic manholes, concrete manholes, cast iron manholes, etc. Manhole covers are usually made of gray cast iron, ductile iron, cast steel, rolled steel, polymers, etc. The center of the cover is cast with marks such as "water supply", "sewage", "rainwater" or "fire-fighting" for easy identification.
