What are Components of Petroleum Production System?

This article provides a brief introduction to the components of petroleum production well.

Wellbore

Wellbore is simply a piping to flow and produce hydrocarbon fluid from the formation. Oil and gas wellbores are constructed like an upside-down telescope. The larger-diameter bore-hole section is at the top of the well.

The last casing in the well is the production casing (or production liner). Once the production casing has been cemented into the well, the production tubing is run into the well. Usually a packer is used near the bottom of the tubing to isolate the annulus between the outside of the tubing and the inside of casing.

Wellhead

It is defined as the surface equipment set below the master valve. It includes casing heads and a tubing head. The casing head is threaded onto the surface casing. Casing head is a mechanical assembly used for hanging a casing string. Several casing heads can be installed during well construction depending on well drilling program design.

The casing head has a bowl that supports the casing hanger. This casing hanger is threaded onto the top of the production casing. As in the case of the production tubing, the production casing is landed in tension so that the casing hanger actually supports the production casing. 

All of these casing head arrangements are supported by the surface casing, which is in compression and cemented to the surface. A well completed with three casing strings has two casing heads.

Christmas Tree

The equipment at the top of the producing wellhead is called a "Christmas Tree". It is used to control flow and is installed above the tubing head. The Christmas tree may have one flow outlet (a tee) or two flow outlets (a cross). The master valve is installed below the tee or cross. To replace a mater valve, the tubing must be plugged. A Christmas tree consists of a main valve, wing valves, and a needle valve. These valves are used for closing the well when required.

Choke Valve

Choke valve is a piece of equipment used to control the flow rate. In most flowing wells, the oil production rate is altered by adjusting the choke size. The choke causes back-pressure in the line. The back-pressure increases the bottom-hole flowing pressure. Increasing the bottom-hole flowing pressure decreases pressure drop from the reservoir to the wellbore. Thus, increasing the back-pressure in the wellbore decreases the flow rate from the reservoir.

Flowline

A flowline is a segment of steel pipe conveying the produced fluids from a wellhead, through a production manifold to a fluid separator of a surface facility.