Oil & Gas Glossary 1.0

See trip margin

An accessory to a fishing tool, placed above it. if the tool cannot be disengaged from the fish, the safety joint permits easy disengagement of the string of pipe above the safety joint. Thus, part of the safety joint and the tool attached to the fish remain in the hole and become part of the fish.

A measurement of load safety for wire rope obtained by using the following formula: Safety Factor - B/W where:

The slight increase in mud weight used to offset friction losses that occur as the mud is circulated through the riser.

A valve that opens at a preset pressure to relieve excessive pressures within a vessel or line. Also called a relief valve, safety valve, or safety relief valve.

The small amount of additional mud weight carried over that needed to balance formation pressure to overcome the pressure-reduction effects caused by swabbing when a trip out of the hole is made.

Abbreviation: surface safety valve.

A tubing safety valve.

A storm choke

Abbreviation: surface-controlled subsurface safety valve.

A special valve installed below the kelly. Usually, the valve is open so that drilling fluid can flow out of the kelly and down the drill stem. It can, however, be manually closed with a special wrench when necessary. In one case, the valve is closed and broken out, still attached to the kelly to prevent drilling mud in the kelly from draining onto the rig floor. In another case, when kick pressure inside the drill stem exists, the drill stem safety valve is close to prevent the pressure from escaping up the drill stem.

An emergency mechanism component enabling the retrieval of a packer (or tubing) if stuck.

An interval device commonly found in subsurface safety valves used to protect the tool's closure mechanism from the wellbore media.

An equipment's working pressure times a safety factor.

See lost circulation. lower kelly cock n: see drill stem safety valve

See lost circulation. lower kelly cock n: see drill stem safety valve

W = calculated total static load. Also called design factor.

A device used to suspend a rod string after the pump has been spaced or when the weight of the rod string must be taken off the pumping equipment.

A small hydraulic line used to communicate fluid from the surface to a downhole tool, such as a subsurface safety valve.

2. a valve installed at the top of the drill stem to prevent flow out of the drill pipe if a kick occurs during tripping operations.

B=nominal catalog breaking strength of the wire rope, and

A device used to control the rate of flow in a line to open or shut off a line completely, or to serve as an automatic or semiautomatic safety device. Those used extensively include the check valve, gate valve, globe valve, needle valve, plug valve, and pressure relief valve.

1. an automatic valve that opens or closes when an abnormal condition occurs (e.g., a pressure relief valve on a separator that opens if the pressure exceeds the set point, or the shutdown valve at the wellhead that closes if the line pressure becomes too high or too low).