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For example, if the points dene the corners of a cube, the crystal is a primitive cubic lattice; if they dene the corners and a point in the center of each face (like a die with a one on every side), the crystal is a face-centered cubic lattice, etc. There are 14 basic types of crystal lattice. Launders: Clarier ef¤uent troughs. Lava: Magma that comes to the earth’s surface. Law of Capture (Hydrocarbon Movement): A legal concept, valid in some places, that since oil and gas are mobile ¤uids, they are not owned until they are produced. Layer: A distinct segment in a vertical stack of formation sequences. Often with areal extent. Laying Down Pipe: To disassemble the drill string into individual joints and lay it down on the pipe racks. Laytime: Time allowed by the shipowner to the voyage charterer or bill of lading holder in which to load and/or discharge the cargo. It is expressed as a number of days or hours. Lay-Up: To dismantle or unrig a ship for a prolonged period of unemployment. LCA: Leak-off control acid. LCA: See Lost circulation control agent. LCM: See Lost circulation materials. LCP: Leakage in closed position. LCTD: Last crystal to dissolve. LD: Lay down. LDC: See Local distribution company. LDC (Transport): Long distance carrier. LDFN: Lay down for night. LDHI (Hydrates): Low dosage hydrate inhibitor. LDLPE: Low-density linear polyethylene. A strong, clear lm ideal for packaging. LDPE: Low-density polyethylene. LDS (Wellhead): Lock down screws. Lead Cement: The rst part of the cement slurry injected-often contaminated during the ¤ow by mixing with mud from the walls of the pipe or the formation. Lead Lines (Pipeline): The lines from a well to a battery. Also called gathering lines. Lead Naphthenate: The lead soap of naphthenic acid that is soluble in mineral oils, used mainly to impart extreme pressure properties to lubricating oils and greases. Leak-Off Rate: The ¤uid lost from the well expressed in volume per time. Leak-Off Test (Drilling): LOT, a drilling test. A LOT is intended to determine the point of leak off. Compare to FIT. Lean Gas: A near dry gas, containing only a trace of condensate. Lease: (1) The legal contract that species the terms and conditions of the business relationship between an oil company and the landowner or mineral

rights holder on a particular tract. (2) A contract between an owner (lessor) and a tenant (lessee), setting forth the compensation, terms, and conditions upon which the lessee may occupy or use property, real or personal, of the lessor. (3) Legal document giving an operator the right to drill for or produce oil or gas; also, the land on which a lease has been obtained. Lease Automatic Custody Transfer: A system of monitoring and transferring oil production for receiving into tankage, measuring, testing, and turning into the pipeline the crude produced on a lease. Lease Automatic Custody Transfer Unit: A calibrated measurement device used as an ofcial sales point for crude oil transfer into a second-party pipeline. Lease Condensate: A mixture consisting primarily of pentanes and heavier hydrocarbons, which is recovered as a liquid from natural gas in lease separation facilities. This category excludes natural gas liquids, such as butane and propane, which are recovered at downstream natural gas processing plants or facilities. See Natural gas liquids. Lease (Drilling): A legal document granting the right to prospect, drill, complete, and produce hydrocarbons on a tract of land. Lease Fuel: Natural gas used in well, eld, and lease operations such as gas used in drilling operations, heaters, dehydrators, and eld compressors. Leasehold Interest: The right to the mineral interest granted by an oil and gas lease and is also called a working or operating interest. Lease Hound: A person that acquires leases and resells them to a drilling company. Lease Setback: The minimum distance away from a lease boundary that a well may be drilled. Least Principal Stress: Minimum principal stress. Hydraulic fractures form perpendicular to this stress. LEL: See Lower explosive limit. Lens: A permeable, often small sedimentary deposit bordered by impermeable rock. Lessee: An organization or individual who obtains a lease from a fee simple owner. In oil and gas, an organization or individual who obtains the mineral rights (the opportunity to look for oil and gas and produce the oil and gas found). Lessor: The fee simple owner or mineral rights owner who allows an individual or organization to explore for and produce oil and gas on mineral rights that he owns. Levelwind: A device in a coiled tubing reel control that aids in controlling spooling of the CT. LFL: See Lower Žammable limit. LHV: See Lower heating value. LIB: Lead impression block. License: An agreement in which a national government gives an oil company the rights to explore for and produce oil and/or gas in a designated area.