- Branche: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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An inexact term describing a borehole (and associated casing program) significantly smaller than a standard approach, commonly a wellbore less than 6 in. In diameter. The slimhole concept has its roots in the observed correlation between well costs and volume of rock extracted. If one can extract less rock, then well costs should fall. One form of slimhole work involves using more or less conventional equipment and procedures, but simply reducing the hole and casing sizes for each hole interval. A second form involves technology used for exploration boreholes in the hard rock mining industry. In the mining rig operations, the drillstem serves a dual purpose. After the hole is drilled, the drillstem remains in the hole and is cemented in place. Then a new drillstem is used for the new hole section, and also cemented in place. The drillstring for mining rig operations is rotated like that for conventional oilfield rotary rig operations, but typically at a much higher speed.
Industry:Oil & gas
An indicator used in place of methyl orange in alkalinity tests. It is green at pH values over 4. 3, but yellow when pH is less than 4. 3.
Industry:Oil & gas
An exploration well. The significance of this type of well to the drilling crew and well planners is that by definition, little if anything about the subsurface geology is known with certainty, especially the pressure regime. This higher degree of uncertainty necessitates that the drilling crews be appropriately skilled, experienced and aware of what various well parameters are telling them about the formations they drill. The crews must operate top-quality equipment, especially the blowout preventers, since a kick could occur at virtually any time. If a wildcat is especially far from another wellbore, it may be described as a "rank wildcat. "
Industry:Oil & gas
Pilot testing may prevent costly mistakes. Pilot testing is a trial run of procedures and instruments that you plan to use. For example, pilot testing of a mail survey to teachers could be done in a couple of different ways. You could mail the survey to a handful of teachers and then call them to discuss the questions. An easier, but less rigorous, method might be to distribute the survey after a professional development activity and ask the teachers there what they think.
The main purpose of pilot testing is to catch potential problems before they become costly mistakes. It is typically used if an instrument or method of data collection is being used for the first time or for the first time with a particular group (e.g., a survey used before with a different age group).
Pilot testing provides information on how long data collection can be expected to take and a preview of how difficult items will be to complete. The latter is important as, with proper advanced notice, you can modify questions and possibly even the way you collect information (e.g., reading questions to people rather than having people read questions themselves).
Industry:Oil & gas
An existing wellbore close to a proposed well that provides information for planning the proposed well. In planning development wells, there are usually numerous offsets, so a great deal is known about the subsurface geology and pressure regimes. In contrast, rank wildcats have no close offsets, and planning is based on interpretations of seismic data, distant offsets and prior experience. High-quality offset data are coveted by competent well planners to optimize well designs. When lacking offset data, the well planner must be more conservative in designing wells and include more contingencies.
Industry:Oil & gas
An electromechanical device used to connect an electrical tool string to a logging cable, electrical wireline or coiled tubing string equipped with an electrical conductor. It provides attachments to both the mechanical armor wires (which give logging cable its tensile strength) and the outer mechanical housing of a logging tool, usually by means of threads. This connection to the logging tool results in a good electrical path from the electrical conductors of the logging cable to the electrical contacts of the logging tool, and shields this electrical path from contact with conductive fluids, such as certain drilling muds. The basic requirements of most cable heads include providing reliable electrical and mechanical connectivity between the running string and tool string. Another attribute of cable heads is that they serve as a "weak link," so that if a logging tool becomes irretrievably stuck in a well, the operator may intentionally pull in excess of the breaking strength of the logging cable head, causing the cable to pull out of the cable head in a controlled fashion.
Industry:Oil & gas
An enlarged region of a wellbore. A washout in an openhole section is larger than the original hole size or size of the drill bit. Washout enlargement can be caused by excessive bit jet velocity, soft or unconsolidated formations, in-situ rock stresses, mechanical damage by BHA components, chemical attack and swelling or weakening of shale as it contacts fresh water. Generally speaking, washouts become more severe with time. Appropriate mud types, mud additives and increased mud density can minimize washouts.
Industry:Oil & gas
An enlarged pipe at the top of a casing string that serves as a funnel to guide drilling tools into the top of a well. The bell nipple is usually fitted with a side outlet to permit drilling fluids to flow back to the surface mud treating equipment through another inclined pipe called a flowline.
Industry:Oil & gas
An emulsion in which oil is the continuous or external phase and water is the internal phase. Invert emulsion usually refers to an oil-base mud, and the terms are considered synonyms. Invert-emulsion muds can be run with 5 to 50% water in the liquid phase, although there are systems that are 100% oil.
Industry:Oil & gas
An electric motor that acts as a brake. Braking is accomplished by reversing the electric fields on the motor, effectively turning it into a generator. The usage of the generated power, either in useful applications or dissipation as heat, restrains the motor-turned-generator and provides a braking action.
Industry:Oil & gas
