Definition - What does Cementing Plug mean?
A Cementing Plug is a separator that acts as a barrier between cement slurry and hydrocarbons present in a reservoir. This plug is made up of rubber and is also known as a wiper plug. The primary purpose of using the plug during cementing jobs is to prevent or reduce any contamination of hydrocarbons from cement slurry and maintain the predictable slurry performance.
Petropedia explains Cementing Plug
As the drilling technology is advancing and there is more urge to extract crude oil, plugging oil or gas wells has become a common and essential process in the extraction process. The cement plug has to be placed properly so that the organization can reduce non-productive rig time, minimize waste material and mitigate the need for additional cementing services. During any cementing operations there are two common types of cementing plugs which are used, i.e., bottom cementing plug and top cementing plug.
The bottom cementing plug is launched into the wellbore way ahead of the cement slurry so that when the cement slurry is added into the wellbore it can minimize the contamination by fluids inside the casing prior to cementing. A diaphragm in the plug body ruptures to allow the cement slurry to pass through after the plug reaches the landing collar. Similarly, the top plug has a solid body that provides positive indication of contact with the landing collar and bottom plug through an increase in pump pressure.