- Industry: Oil & gas
- Number of terms: 8814
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Any small component of the drillstring, such as a short drill collar or a thread crossover.
Industry:Oil & gas
Any pit not part of the active (circulatory) system. The reserve pit may be used to store spare or waste mud, base oil or brine. In operations on land, the reserve pit is usually a plastic-lined, earthen pit, in which waste mud is stored until final disposal.
Industry:Oil & gas
Any of a number of liquid and gaseous fluids and mixtures of fluids and solids (as solid suspensions, mixtures and emulsions of liquids, gases and solids) used in operations to drill boreholes into the earth. Synonymous with "drilling mud" in general usage, although some prefer to reserve the term "drilling fluid" for more sophisticated and well-defined "muds. " Classifications of drilling fluids has been attempted in many ways, often producing more confusion than insight. One classification scheme, given here, is based only on the mud composition by singling out the component that clearly defines the function and performance of the fluid: (1) water-base, (2) non-water-base and (3) gaseous (pneumatic). Each category has a variety of subcategories that overlap each other considerably.
Industry:Oil & gas
Any of a number of fluids (liquids) manufactured from starting products of known composition and purity. Popular fluid types include several olefin oligomers of ethylene. Esters made from vegetable fatty acid and alcohol were among the first such fluids. Ethers and polyethers, made from alcohols and polyalcohols, have been used, along with paraffinic hydrocarbons and linear alkyl benzenes. Mixtures of these fluids are also used to make synthetic-base muds.
Industry:Oil & gas
Any liquid used to physically separate one special-purpose liquid from another. Special-purpose liquids are typically prone to contamination, so a spacer fluid compatible with each is used between the two. The most common spacer is simply water. However, chemicals are usually added to enhance its performance for the particular operation. Spacers are used primarily when changing mud types and to separate mud from cement during cementing operations. In the former, an oil-base fluid must be kept separate from a water-base fluid. In this case, the spacer may be base oil. In the latter operation, a chemically treated water spacer usually separates drilling mud from cement slurry. For proper performance and to prevent unanticipated problems, the spacer should be tested with each fluid in small-scale pilot tests. Some spacer fluids are designed to induce a particular flow regime. Ideally, a cement slurry should have turbulent flow to efficiently displace drilling fluids, but there might be pumping restrictions on fluid velocity. Therefore, a spacer that can achieve turbulent or pseudolaminar flow might be selected.
Industry:Oil & gas
Any gas deliberately introduced into the mud system to help a mudlogger or wellsite geologist track the amount of time or the number of mud pump strokes it takes to circulate mud from the kelly downhole through the drillstring to the bit, and back uphole to the gas trap at the shale shaker. This interval is used to calculate the lag period.
Industry:Oil & gas
Any chemical reaction with water (H<sub>2</sub>O), such as degradation of lignite by decarboxylation of humic acid (a major component of lignite), which is driven by hydrolysis at high pH and begins at modest temperature.
Industry:Oil & gas
Any aqueous solution that contains a buffer mixture (weak acid or weak base and salt of the weak acid or base) to maintain constant or almost constant pH of the system.
Industry:Oil & gas
An unusual occurrence of hydrocarbon in which molecules of natural gas, typically methane, are trapped in ice molecules. More generally, hydrates are compounds in which gas molecules are trapped within a crystal structure. Hydrates form in cold climates, such as permafrost zones and in deep water. To date, economic liberation of hydrocarbon gases from hydrates has not occurred, but hydrates contain quantities of hydrocarbons that could be of great economic significance. Hydrates can affect seismic data by creating a reflection or multiple.
Industry:Oil & gas
