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.

A check valve in the drill string that will allow fluid to be pumped into the well but will prevent flow from entering the string.

A method by which a floating offshore drilling rig is maintained in position over an offshore well location without the use of mooring anchors.

Generally, several propulsion units, called thrusters, are located on the hulls of the structure and are actuated by a sensing system.

A computer to which the system feeds signals directs the thrusters to maintain the rig on location.

The conventional method of formation testing.

The basic drill stem test tool consists of a packer or packers, valve or ports that may be opened and closed from the surface, and two or more pressure-recording devices.

The tool is lowered on the drill string to the zone to be tested.

The packer or packers are set to isolate the zone from the drilling fluid column.

The valves or ports are then opened to allow for formation flow while the recorders chart static pressures.

A sampling chamber traps dean formation fluids at the end of the test.

Analysis of the pressure charts is an important part of formation testing.

A generic term, originally a trademark name, used to describe a stage tool, used in selective zone primary cementing.

See kelly bushing

A single well that produces from two separate formation at the same time.

Production from each zone is segregated by running two tubing strings with packers inside the single string of production casing, or by running one tubing string with a packer through one zone while the other is produced through the annulus.

In a miniaturized dual completion, two separate 4 1/2-inch or smaller casing strings are run and cemented in the same wellbore.

A piece of pipe that has been twisted off inside a female connection; or a short section of material, such as belting or pipe, used to lengthen existing equipment.

To bore a hole in the earth, usually to find and remove subsurface formation fluids such as oil and gas.

1.

The operation during the drilling procedure when the cement is drilled out of the casing and the wellbore after the casing has been cemented.

2.

To remove the settlings and cavings that are plugged inside a hollow fish (such as drill pipe) during a fishing operation.

1.

A sudden increase in the drill bit’s rate of penetration.

It sometimes indicates that the bit has penetrated a high-pressure zone and thus warns of the possibility of a kick.

2.

A sudden increase in the rate of penetration during drilling.

When this increase is significant (two or more times the normal speed, depending on local conditions), it may indicate a formation change, a change in the pore pressure of the formation fluids, or both.

It is commonly interpreted as an indication of the bit drilling sand (high-speed drilling) rather than shale (low-speed drilling).

The fast-drilling formation may or may not contain high-pressure fluids.

Therefore, the driller commonly stops drilling and performs a flow check to determine if the formation is flowing.

If the well is flowing, or if the results are uncertain, the driller may close the blowout preventers or circulate bottoms-up.

Depending on the bit being used and the formations being drilled, a formation, even if sand, may sometimes drill slower rather than faster.

This slowing of drilling progress, while technically also a drilling break, is usually referred to as a “reverse drilling break”, or simply “reverse break.”

A specially compounded liquid circulated through the wellbore during rotary drilling operations.

See mud.

See keyway.

A cycle, or down the hole and back, is the time required for the pump to move the drilling fluid in he hole.

The cycle in minutes equals the barrels of mud in the hole divided by barrels per minute.

1.

To remove with the drill bit the residual cement that normally remains in the lower section of casing and the wellbore after the casing has been cemented.

2.

To remove the settlings and cavings that are plugged inside a hollow fish (such as drill pipe) during a fishing operation.