Down hole tools inserted in the drill-string when fishing to jerk or jar the fish free by repeated sudden blows. They may also be used while drilling to avoid the drill-string becoming stuck. JOINT
A single length of pipe. Coupled or welded to other lengths, joints become a string. The term joint may also refer to the couplings or joints themselves.JUNK
Any unwanted object 'lost' down a well.
Square or hexagonal steel pipe about 43 feet (13 metres).KILLING A WELL
The act of bringing a well under control which has blown out or is threatening to blow out; also applies to the procedure of circulating water and mud into a completed well before starting well service operations.
LAYING DOWN PIPE
The operation of pulling drill pipe or tubing from the hole and laying it down on the pipe rack. LEASE
A legal document executed between a landowner, as lessor, and a company or individual (as lessee) that conveys the right to exploit the premises for minerals or other products for a specified period of time over a given area. LEASE SALE
An MMS proceeding by which leases of certain OCS tracts are offered for lease by competitive sealed bidding and during which bids are received, announced, and recorded. LIQUIDS
Hydrocarbons in solution in natural gas which are liquefiable at surface temperature and pressure or by treatment and processing. LITHOLOGY
The study of rocks and hence the description of different formations encountered by a well.LOG/LOGGING
Systematic recording of data. To conduct a survey inside a borehole to gather information about the subsurface formations; the results of such a survey. Logs typically consist of several curves on a long grid that describe properties within the well-bore or surrounding formations that can be interpreted to provide information about the location of oil, gas, and water. Also called well logs, borehole logs, wireline logs.LOST CIRCULATION
Loss quantities of whole mud to a formation, usually cavernous, fissured, or coarsely permeable beds. It is indicated by the complete or partial loss of drilling mud returns. Until the zone in which the drilling fluid has been lost is sealed off, drilling cannot be resumed in most cases.
Refers to progress being made at a given time when the bit is rotating and the well-bore is being deepened. In other words, drilling. MAKING A TRIP
Hoisting of the drill string out of, and returning it into, the well bore. This is done for the purpose of changing bits, preparing to take a core, etc. MAKE UP/BREAK OUT
To assemble/screw together the sections of joints of a string of pipe. 'Breaking out' is the opposite.MARGINAL
A well, development, etc. whose commercial profitability is in doubt.MIGRATION
Hydrocarbons are often found in formations other than those in which their organic source was deposited. This movement often over considerable distances is known as migration. A process applied to data recorded, e.g. in a "3-D" seismic survey, to adjust for the effects of the "oblique" angle at which it was gathered. MILLIDARCY
See DarcyMINIMUM ROYALTY
The lowest payment a lessee can pay on an OCS lease after production begins. It is equivalent to the yearly rental, typically $3 per acre or $8 per hectare. Rentals are paid annually before a discovery; royalties are paid on production after a discovery. If the total royalty payments amount to less than the yearly rental, the minimum royalty payments make up the difference. MMBBL
Millions of barrels of oil equivalent.MMSCFD
Millions of standard cubic feet per day.MUD
Mud is the name given to drilling fluid which is mainly a mixture of water, or oil distillate, and 'heavy' minerals such as Bentonite or Barites. Mud is pumped into a well at densities calculated to provide a hydrostatic pressure sufficient to overcome downhole formation pressures. (See e.g. Gas Kick). In addition, the mud is continuously circulated down to the bit, and returns in the annular space outside the drill-string, bringing with it rock cuttings for inspection and keeping the well clean. It is also engineered to maintain a thin protective layer of filter-cake on the bore hole wall, without excessive weight which would decrease the weight on the bit and hence penetration ( see Drill String), and also possibly lead to differential sticking and formation damage. Mud is pumped from the mud pit (or tank) via the standpipe, rotary hose and gooseneck to the swivel, and into the drill stem. On return from down hole it is recovered and rock cuttings removed by the shale shakers before re-circulation. A Mud Log is the record of mud make-up and analysis of cuttings recovered.MULTIPLE ZONE WELL COMPLETION
Completion of a well in such a way that production is obtained from several different formations.