A casing shoe is positioned at the bottom of a pipe lowered into a wellbore. This pipe, called the casing string, needs to be carefully guided so it is properly and safely positioned. The shoe keeps the casing string aligned as it progresses into the wellbore, allowing technicians to be assured that the process is going smoothly. Several casing shoe designs are available for different needs.
The device consists of a metal collar fitted at the base of the casing string, and held in place by the casing hanger at the top. Some designs are snub-nosed, with the angled edges allowing the casing shoe to nudge into the wellbore and stay evenly positioned. Others may have cutting teeth. These can be necessary if the walls of a wellbore are bulging inward and materials are clogging the way; the casing shoe can cut through the to allow the pipe to pass.
Such equipment makes it possible to lower a casing string safely past potential obstructions, ledges, and various obstacles inside the wellbore. Technicians still need to move carefully, monitoring the casing string for signs of fatigue and stress that might potentially cause a problem. This process can be painstaking and very expensive, because technicians want to make sure it is performed correctly. They also need to secure the casing string to confirm that it won’t drop unexpectedly, and so they can maintain control over it at all times.
Technicians assemble the casing string with care, using the components recommended for a given well. They also inspect the casing shoe and other features to make sure they are firmly attached and in good working order. Losing components down a well can be a costly mistake, and workers want to avoid this if at all possible. In the event of an incident, their records may be reviewed to determine if negligence was the cause, or if the accident would have occurred anyway.
Casing shoes are produced by a number of manufacturers who make oil and gas components. They can meet standardized guidelines and may also be designed to fit specifically with a given company’s products. For special needs, custom versions can be produced on behalf of customers with challenging applications or projects that might require unique equipment. The cost can vary, depending on the design and the components used, and in some cases preferential pricing may be available as part of a larger package of drilling equipment.