A liner hanger is a device used in oil fields to hang liners within an oil well. So that oil can be pumped out of the well, a liner is used to create a vacuum. Liners can be installed mechanically or hydraulically, depending on the well. Setting a hanger is a crucial part of the process of "completion" which is the preparation of an oil well for drilling.
Mechanical liner hangers are designed to be used on vertical, onshore wells. These are durable machines capable of providing light to medium density liners. A mechanical liner hanger is lowered into a well and when it reaches its intended depth it attaches itself to the well’s cones, which are components that keep oil and dangerous gasses from escaping. Through using its mechanical parts, the liner hanger attaches itself to the cone, allowing for oil to pass through to the surface.
For offshore oil wells, onshore wells that are extremely deep, or high pressure high temperature (HPHT) wells, hydraulic liner hangers are used. These hang heavy liners and can be used horizontally as well as vertically. If the well is to be cemented, it is possible for the lining and cementing to be done simultaneously with hydraulic liner hangers, as this improves the stability of both the cement and the liner. As the name suggests, when the hydraulic liner hanger reaches its intended depth it attaches the liner to the cone by using powerful hydraulics.
The process of cementing is generally a part of “completion” as well and can be done before, after or during the use of the liner hanger. Cementing allows the well to be more stable, but in some cases it is not desirable and can also be left out of the process entirely. Wells without cement are generally shallow onshore wells with hydraulically set light liners. These wells are not cemented because the liner may need to be rotated occasionally within the well. Also the lining is more flexible without cement, allowing larger amounts of oil to be pumped at once.
New liner hanger technology allows for cemented wells to use expandable liner hangers as well. This method is available for onshore and offshore wells and uses advanced technology to form an attachment with the cones that no longer require that workers swivel the lining to maintain a consistent flow. Since there is a constant demand for more efficient ways of extracting oil, such as this method, liner hanger technology can be expected to see more breakthroughs in the coming years.