land rig n: any drilling rig that is located on dry land.
latch on v: to attach elevators to a section of pipe to pull it out of
or run into the hole.
latch sub n: a device, usually with segmented
threads, run with seal subs on the bottom of a tubing string and latched into
a permanent packer to prevent tubing movement.
lay n: 1. the spiral of strands in a wire rope either to the right or
to the left, as viewed from above. 2. a term used to measure wire rope,
signifying the linear distance a wire strand covers in one complete rotation
around the rope.
lay down pipe v: to pull drill pipe or tubing from the hole and place
it in a horizontal position on a pipe rack. Compare set back.
lead-tong hand (pronounced “leed”) n: the crew
member who operates the lead tongs when drill pipe and drill collars are being
handled. Also called lead-tong man.
lead tongs (pronounced “leed”) n pl: the pipe tongs suspended in
the derrick or mast and operated by a chain or a wire rope connected to the
makeup cathead or the breakout cathead.
lifting sub n: a threaded device placed in the end
of tubulars, such as drill collars to aid in lifting; also called hoisting
liner n: 1. a string of pipe used to case open hole below existing
casing. A liner extends from the setting depth up into another string of
casing, usually overlapping about 100 feet (30.5 meters) above the lower end
of the intermediate or the oil string. Liners are nearly always suspended from
the upper string by a hanger device. 2. a relatively short length of pipe with
holes or slots that is placed opposite a producing formation. Usually, such
liners are wrapped with specially shaped wire that is designed to prevent the
entry of loose sand into the well as it is produced. They are also often used
with a gravel pack. 3. in jet perforation guns, a conically shaped metallic
piece that is part of a shaped charge. It increases the efficiency of the
charge by increasing the penetrating ability of the jet. 4. a replaceable tube
that fits inside the cylinder of an engine or a pump. See cylinder liner.
liner completion n: a well completion in which a
liner is used to obtain communication between the reservoir and the wellbore.
liner hanger n: a slip device that attaches the
liner to the casing. See liner.
location n: the place where a well is drilled. Also called well site.
log n: a systematic recording of data, such as a
driller’s log, mud log, electrical well log, or radioactivity log. Many
different logs are run in wells to discern various characteristics of downhole
formation. v: to record data.
log a well v: to run any of the various logs used to
ascertain downhole information about a well.
logging devices n pl: any of several electrical, acoustical,
mechanical, or radioactivity devices that are used to measure and record
certain characteristics or events that occur in a well that has been or is
long string n: 1. the last string of casing set in a
well. 2. the string of casing that is set at the top of or through the
producing zone, often called the oil string or production casing.
lost circulation n: the quantities of whole mud lost
to a formation, usually in cavernous, pressured, or coarsely permeable beds.
Evidenced by the complete or partial failure of the mud to return to the
surface as it is being circulated in the hole.
lost pipe n: drill pipe, drill collars, tubing, or
casing that has become separated in the hole from the part of the pipe
reaching the surface, necessitating its removal before normal operations can
proceed; for example, a fish.
lost time incident n: an incident in the workplace
that results in an injury serious enough that causes the person injured to be
unable to work for a day or more.
lubricator n: a specially fabricated length of
casing or tubing usually placed temporarily above a valve on top of the
casinghead or tubing head. It is used to run swabbing or perforating tools
into a producing well and provides a method for sealing off pressure and thus
should be rated for highest anticipated pressure.