- Industry: Oil & gas
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In a U-tube manometer, the height of one leg of fluid changed by altering the density of some of the fluid in the other leg. In a well with drillpipe in the hole, the string of drillpipe is one leg and the annulus between the drillpipe and the wellbore is the other. If a denser mud goes into the drillpipe, mud flows up the annulus, and vice versa. The practice of putting a dense slugging pill in the drillpipe in order to pull a dry string makes use of the U-tube effect.
Industry:Oil & gas
In chemical analysis, a procedure to determine the amount of a constituent in a sample by adding a measured volume of reagent until the reaction between the constituent of interest and the reagent is completed, as shown by an appropriate endpoint indicator. For mud and mud filtrate analyses, titration is a common procedure for determining alkalinity, chloride, total hardness, methylene blue capacity and formaldehyde.
Industry:Oil & gas
In a nuclear magnetic resonance (NMR) measurement, referring to the cycle of radio frequency pulses designed by Carr, Purcell, Meiboom and Gill to produce pulse echoes and counteract dephasing due to magnetic field inhomogeneities. In the CPMG sequence, an initial radio frequency pulse is applied long enough to tip the protons into a plane perpendicular to the static magnetic field (the 90<sup>o</sup> pulse). Initially the protons precess in unison, producing a large signal in the antenna, but then quickly dephase due to the inhomogeneities. Another pulse is applied, long enough to reverse their direction of precession (the 180<sup>o</sup> pulse), and causing them to come back in phase again after a short time. Being in phase, they produce another strong signal called an echo. They quickly dephase again but can be rephased by another 180<sup>o</sup> pulse. Rephasing is repeated many times, while measuring the magnitude of each echo. This magnitude decreases with time due to molecular relaxation mechanisms surface, bulk and diffusion. One measurement typically may comprise many hundreds of echoes, while the time between each echo (the echo spacing) is of the order of 1 ms or less. <br><br>Carr HY and Purcell EM: ?Effects of Diffusion on Free Precession in Nuclear Magnetic Resonance Experiments,? Physical Review 94, no. 3 (1954): 630-638. <br><br>Meiboom S and Gill D: ?Modified Spin-Echo Method for Measuring Nuclear Relaxation Times,? The Review of Scientific Instruments 29, no. 8 (1958): 688-691.
Industry:Oil & gas
In a cement slurry, the ratio of water to cement expressed as percent; the number of parts of water used to mix with 100 parts of cement.
Industry:Oil & gas
In a broad sense, very small particles, either in a mud or a mud additive sample.
Industry:Oil & gas
Hydroxypropyl starch is a derivative of natural starch, used primarily for fluid-loss control in drilling muds, drill-in, completion and workover fluids. Being nonionic, it is only slightly affected by salinity and hardness in fluids. Linear and branched carbohydrate polymers in natural starch have three reactive OH groups on each glucose unit. During manufacture, these polymers are reacted with propylene oxide, adding hydroxypropyl (CH(OH)CH<sub>2</sub>CH<sub>3</sub>) groups at the OH positions by an ether linkage. By adding the hydroxypropyl groups, the HP starch becomes more resistant to thermal degradation and bacterial attack.
Industry:Oil & gas
Hydrogen ion potential, which is the log<sub>10</sub> of the reciprocal of hydrogen ion, H<sup>+</sup>, concentration. Mathematically, pH = log<sub>10</sub> (1/(H<sup>+</sup>)), where ( ) represents mole/L. PH is derived from the ion-product constant of water, which at room temperature is 1 x 10<sup>-14</sup> = (H<sup>+</sup>) x (OH<sup>-</sup>). Pure water (at neutral pH) has equal concentrations of its two ions: (H<sup>+</sup>) = (OH<sup>-</sup>) = 10<sup>-7</sup> mole/L. Log<sub>10</sub> 1/(H<sup>+</sup>) is 7, which is the pH of a neutral solution. The pH scale ranges from 0 to 14, and values below 7 are acidic and above 7 are basic.
Industry:Oil & gas
Having the same center, such as when the casing and the wellbore have a common center point and, therefore, a uniform annular dimension.
Industry:Oil & gas
Gel strengths that are very low, with both values near zero, when measured at 10 seconds and 10 minutes according to standardized test procedures. Settling of barite and cuttings may occur in a zero-zero gels mud.
Industry:Oil & gas
Hard granular nodules composed essentially of hydraulic calcium silicates, with smaller quantities of calcium aluminates and ferrites. Portland cement clinker is produced by the heat treatment of cement raw materials in a kiln. Clinker is pulverized with gypsum in the manufacture of portland cement.
Industry:Oil & gas
