- Settore: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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A negatively charged ion. Clay surfaces, groups on polymer chains, colloids and other materials have distinct, negatively charged areas or ions. Anionic characteristics affect performance of additives and contaminants in drilling fluids, especially water muds, in which clays and polymers are used extensively.
Industry:Oil & gas
A needle-like clay mineral composed of magnesium-aluminum silicate. Major deposits occur naturally in Georgia, USA. Attapulgite and sepiolite have similar structures and both can be used in saltwater mud to provide low-shear rate viscosity for lifting cuttings out of the annulus and for barite suspension. Attapulgite and sepiolite are sometimes called "salt gel. " Attapulgite has no capability to control the filtration properties of the mud. For use as an oil mud additive, the clay is coated with quaternary amine, which makes it oil-dispersible and provides gel structure but does not improve the filter cake, unlike organophilic bentonite clay.
Industry:Oil & gas
A natural starch derivative. CMS is used primarily for fluid-loss control in drilling muds, drill-in, completion and workover fluids. It is slightly anionic and can be affected by hardness and other electrolytes in a mud. CMS is similar to CMC (carboxymethylcellulose) in method of manufacture and many of its uses. The linear and branched starch polymers in natural starch react with monochloroacetic acid in alkaline solution, adding carboxymethyl groups at the OH positions by an ether linkage. By adding the carboxymethyl groups, the starch becomes more resistant to thermal degradation and bacterial attack.
Industry:Oil & gas
A mud that has fewer solids than conventional clay-based muds of the same density and similar use. Low-solids mud design and maintenance is accomplished primarily by substituting one or more polymers for the ordinary bentonite clay. Viscosity can be obtained either entirely by polymers or by using a premium quality (nontreated) bentonite along with the appropriate extender polymer. Together, these give rheology comparable to that of a higher concentration of ordinary bentonite. Polyanionic cellulose (PAC) may be needed for fluid-loss control. XC polymer can be effective for cuttings carrying. By combining premium bentonite and the right extender polymer, PAC and XC polymer, solids can be kept low, if solids control is required. This concept applies best to low-density muds, below about 13 lbm/gal, but has some validity in all muds.
Industry:Oil & gas
A mud-flow device, also called a jet hopper, in which materials are put into the circulating mud system. The mud hopper is powered by a centrifugal pump that flows the mud at high velocity through a venturi nozzle (jet) below the conical-shaped hopper. Dry materials are added through the mud hopper to provide dispersion, rapid hydration and uniform mixing. Liquids are sometimes fed into the mud by a hose placed in the hopper.
Industry:Oil & gas
A mud whose density is high enough to produce a hydrostatic pressure at the point of influx in a wellbore and shut off flow into the well. Kill-weight mud, when needed, must be available quickly to avoid loss of control of the well or a blowout. Thus, it is usually made by weighting up some of the mud in the system or in storage by adding barite or hematite. Unless diluted in advance, the mud may become too thick and perhaps un-pumpable due to high solids loading. A weight-up pilot test can identify if and how much dilution will be needed in advance of adding weighting material to the mud in the pits.
Industry:Oil & gas
A mud test in which the mud sample is not agitated. This test is usually performed at a selected high temperature. Typically, the mud sample is sealed in a mud-aging cell and placed in an oven for a given period of time (often 16 hours, overnight). The cooled mud is tested before it is stirred. Commonly, the sample is retested after it has been stirred. Static-aged mud, before it is stirred, simulates a mud that is static in a well while pipe is out of the hole during a bit trip or logging run. The stirred mud simulates the same mud after arriving at the surface and after being agitated by mud guns and through centrifugal pumps. The amount and kind of mud treatment are determined from these tests.
Industry:Oil & gas
A mud that slows or stops hydration, swelling and disintegration of shales. A variety of mud types have been labeled as "inhibitive muds. " The degree of inhibition is not quantitative, but qualitatively they range from highly inhibitive (balanced-activity oil muds), moderately inhibitive (potassium muds and silicate muds), fairly inhibitive (calcium-based fluids) to slightly inhibitive (lignosulfonate, lignite water muds) to non-inhibitive (freshwater, nontreated muds).
Industry:Oil & gas
A mud that is excessively viscous, having high gel strengths and high yield point. A gelled-up mud may not be pumpable without exceeding limits on pump pressure. Often caused by excessive solids content, especially colloidal solids, or, in the case of oil or synthetic muds, by low temperature.
Industry:Oil & gas
A mud that does not conduct electricity sufficiently well to allow spontaneous potential (SP) logging or resistivity logging. Oil- and synthetic-base muds are nonconductive drilling fluids. Water muds are not in this category.
Industry:Oil & gas
