Manifold used to lower the pressure from the wellhead. It consist of a set of high pressure valves and at least two chokes. These chokes can be fixed or adjustable or a mix of both. The redundancy is needed so that if one choke has to be taken out of service, the flow can be directed through another one.
By lowering pressure the retrieved gases can be flared off on site choke manifold systems manage well pressure fluctuations encountered during drilling by diverting flow through a series of valves and chokes.
An arrangement of piping and special valves, called chokes. In drilling, mud is circulated through a choke manifold when the blowout preventer is closed; a choke manifold is also used to control the pressures encountered during a kick. In well testing, a choke manifold attached to the wellhead allows flow and pressure control for test components downstream.
As a general standard, the valves downstream the choke have the half pressure rating of the valves upstream the choke. For instance, if the inboard valves are 10000 psi working pressure, the downstream valves can be 5000 psi working pressure.
The redundancy in the choke manifold is more than necessary when the complex and difficult situation are predicted to be faced during operations
The drilling chokes which are used in the drilling manifolds are categorized in two main types according to the system used to achieve choking. In order to achieve choking in the first category, two surfaces with openings are rotated against each other to allow or restrict the flow.
Swaco Super Choke falls in this category, it is composed of two tungsten carbide plates with half-moon openings. One plate is fix while the other one can be rotated hydraulically. In the second category, the choking is achieved by inserting a tungsten carbide bean into tungsten carbide sleeve. The Cameron Drilling choke falls in this category.
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