| A-FRAME: 1. a derrick or crane shaped like the letter A and used to handle heavy loads. 2. an A-shaped openwork structure that is the stationary and supporting component of the mast of a jackknife rig and to which the mast is anchored when it is in an upright or drilling position. 3. the uppermost section of a standard derrick, shaped like the letter A and used as a support in lifting objects such as the crown block to the water table. |
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| A-MAST: an A-shaped arrangement of upright poles, usually steel, used for lifting heavy loads. See A-frame. |
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| ABAFT: 1. toward the stern of a ship or mobile offshore drilling rig. 2. behind. 3. farther aft than. See aft. |
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ABANDON: to cease producing oil and gas from a well when it becomes unprofitable or to cease further work on a newly drilled well when it proves not to contain profitable quantities of oil or gas. Several steps are involved: part of the casing may be removed and salvaged; one or more cement plugs are placed in the borehole to prevent migration of fluids between the different formations penetrated by the borehole; and the well is abandoned. In most oil-producing states, it is necessary to secure permission from official agencies before a well may be abandoned.
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ABANDONED WELL: a well not in use because it was a dry hole originally, or because it has ceased to produce. Statutes and regulations in many states require the plugging of abandoned wells to prevent the seepage of oil, gas, or water from one stratum of underlying rock to another.
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| ABANDONMENT: sealing, or abandoning, a well in which production or injection is no longer, or never was viable. Permission from local regulatory agencies is typically required, which usually entails plugging the productive intervals to prevent crossflow and setting a surface cement plug. |
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| ABANDONMENT PRESSURE: the average reservoir pressure at which an amount of gas insufficient to permit continued economic operation of a producing gas well is expelled. |
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| ABNORMAL PRESSURE: pressure exceeding or falling below the pressure to be expected at a given depth. Normal pressure increases approximately 0.465 pounds per square inch per foot of depth or 10.5 kilopascals per meter of depth. Thus, normal pressure at 1,000 feet is 465 pounds per square inch; at 1,000 meters it is 10,500 kilopascals. See pressure gradient. |
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| ABRASION: wearing away by friction. |
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