- Industry: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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An enhanced oil recovery method in which carbon dioxide (CO<sub>2</sub>) is injected into a reservoir to increase production by reducing oil viscosity and providing miscible or partially miscible displacement of the oil.
Industry:Oil & gas
An emulsion with large and widely distributed droplets. A loose emulsion can be easy to break.
Industry:Oil & gas
An emulsion with small and closely distributed droplets. A tight emulsion can be difficult to break.
Industry:Oil & gas
An element, or mineral, that is particularly effective in absorbing thermal neutrons (neutrons with about the same energy as the surrounding matter, typically less than 0. 4 eV). The elements gadolinium, boron, chlorine, hydrogen and iron are thermal absorbers (in decreasing order of effectiveness). The effect of chlorine is used in a pulsed neutron capture log to distinguish salty water from hydrocarbons. In a thermal neutron porosity measurement, the effect of hydrogen is important, while boron and iron affect the response in shales.
Industry:Oil & gas
An encapsulated radioactive material that emits neutrons for use in neutron porosity measurements. The most common source relies on alpha-beryllium reactions in a <sup>241</sup>Am-Be mixture. Beryllium releases a neutron of approximately 4 MeV when struck by an alpha particle. The americium is the source of alpha particles. <sup>253</sup>Californium fission is an intense source of 2. 3 MeV neutrons but is used only in special applications due to its short half-life of 2. 65 years and special licensing requirements.
Industry:Oil & gas
An element with an atomic number of 92. The <sup>238</sup>U isotope is radioactive and decays with a half-life of 4. 4 * 10<sup>9</sup> years through a series of intermediate isotopes to a stable isotope of lead. The intermediate isotopes emit a wide range of gamma rays, the most prominent being that of bismuth, <sup>214</sup>Bi. It is assumed that formations are in secular equilibrium; that is, the relative proportions of parent and daughter isotopes remain constant, and the measured spectrum is directly related to the amount of <sup>238</sup>U. The concentration in the Earth?s crust is about 4 ppm by weight. <br><br>Uranium-bearing minerals are rare. Uranium is a soluble trace element that is transported easily and can be precipitated far from its source. It is most frequently found in carbonates and organic materials. A log of uranium is presented in parts per million, ppm. It is useful for detecting organic material, but is otherwise considered not useful for quantitative evaluation. In the corrected gamma ray log, the uranium contribution is removed to differentiate carbonates from shales.
Industry:Oil & gas
An element with an atomic number of 90. The <sup>232</sup>Th isotope is radioactive and decays with a half-life of 1. 4 * 10<sup>10</sup> years through a series of intermediate isotopes to a stable isotope of lead. The intermediate isotopes emit a wide range of gamma rays, the most prominent being that of thallium, <sup>208</sup>Tl. It is assumed that formations are in secular equilibrium; that is, the relative proportions of parent and daughter isotopes remain constant, and the measured spectrum is directly related to the amount of <sup>232</sup>Th. The concentration in the Earth's crust is about 12 parts per million, ppm, by weight. <br><br>Thorium-bearing minerals are rare. Thorium is a trace element associated with clays and heavy minerals. It is very immobile so that quantity measured today probably was present at the time of deposition. A log of thorium is presented in parts per million. It is often a good measure of clay content.
Industry:Oil & gas
An element with an atomic number of 19. The <sup>40</sup>K isotope is radioactive, decaying with the emission of a single gamma ray of 1. 46 MeV with a half-life of 1. 3 * 10<sup>9</sup> years to give a stable isotope of argon. Potassium is the largest source of natural radioactivity. It occurs in illite, alkali feldspars, micas and some evaporite minerals. It also occurs in some drilling mud systems. The <sup>40</sup>K isotope is only a small fraction, about 0. 012%, of the total potassium, the main isotope being <sup>39</sup>K, which has an abundance of about 1. 7% in the Earth's crust. For the purposes of logging, the total potassium is calculated from the measured quantity of <sup>40</sup>K and scaled in percent by weight. It is a valuable aid in determining the mineral content of a formation.
Industry:Oil & gas
An electrode on a laterolog sonde that focuses the current sent by the central current-emitting electrode (A0). The guard electrode is held at the same potential as A0, thereby forcing the current from A0 to run approximately perpendicular to the sonde into the formation, and preventing it from running up the borehole to a great extent.
Industry:Oil & gas
An electrode device with small spacings from which the current flow, and hence the measurement, is focused a short distance into the formation. The proximity log measures the resistivity of the flushed zone with minimum influence from the mudcake or the undisturbed zone. The central current-emitting electrode (A0) is surrounded by a guard electrode that emits sufficient current to focus the current from A0 a certain distance into the formation. The electrodes are mounted on a pad that is pressed against the borehole wall. In a typical tool design, 90% of the signal comes from within 5 to 10 in. (13 to 25 cm) of the pad. This is deeper than the microlaterolog, which ensures that the mudcake has less effect but means that the proximity log is more often affected by the undisturbed zone.
Industry:Oil & gas
