A bell nipple is a type of pipe that is commonly employed in a number of drilling operations. The design of the pipe typically allows for the section to serve the purpose of a funnel that is used to maneuver drilling tools into the top area of the drilling site. Once commonly used in offshore rigging as well as land drilling sites, the bell nipple remains a popular option for site on land but has largely been replaced by other methods when it comes to rigs located at sea.
The basic configuration of the bell nipple is found on the top end of what is known as the casing string. Sporting a larger end, the nipple makes it easier for rig workers to move various types of tools into position and direct their use in the drilling operation. It is not unusual for the pipe to also be equipped with some type of side valve or outlet that aids in allowing any fluids introduced in the well to be expelled when and as necessary. This flow line arrangement is often necessary to make it easier to remove the fluids as part of the pumping process, keeping the contamination of the oil to a minimum.
Along with aiding in controlling the introduction of equipment, a bell nipple may also be an integral part of the well design that helps to increase safety on the site. It is not unusual for the nipple to be connected to the blowout preventers, which are devices that aid in keeping the well stable and minimizing the risk to the workers on the rig. Since the pipe is usually equipped with some sort of side valve and flow line, it can also be used to control the removal of mud from the well as the shaft is dug, depositing the collected product into mud tanks.
While the bell nipple is still in common use on land-based drilling sites, the use of this particular component is less likely to be included in the configuration of drill sites located at sea. Other approaches to guiding equipment and creating flow lines are used in those situations, making it easier to account for the water pressure and other factors relevant to offshore drilling. On land, the bell nipple remains an efficient and viable part of most drilling operations, although that use may be augmented with more recent developments in drilling technology.