Definition - What does Surface Casing mean?
A Surface Casing is a pipe string with a large diameter that is the first one to be set in a well. It is a low-pressure pipe which is cemented first in the well to act as a protective shield to preserve the water aquifers in the region. The Surface Casing is done before the drilling process is started, so that the blowout preventer system can be installed. It also helps in installing the tubing and deep casing strings, and prevents a condition known as lost circulation. It is also known as a surface pipe.
Petropedia explains Surface Casing
A Surface Casing is an initial casing set that is installed in a well by cementing it. This casing is important and helpful in a wide number of situations. When an oil well is being drilled, the Surface Casing is installed in the first place which helps in protecting the borehole from falling. The Surface Casing comes in contact with the surface of the formations, and thus, it acts as a preeminent protective casing. The following are some of the reasons why a Surface Casing is important:
- It protects the fresh water aquifers by preventing the drilling fluids, gases and chemicals from seeping into the underground water reservoirs.
- It acts as an important element for the installation of a blowout preventer system on top of it.
- It also acts as an important structure to host other casing strings inside and on top of it, relatively because it has a large diameter.