- Отрасли: Oil & gas
- Number of terms: 8814
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An indicator used to determine the effect that key completion components have on the production efficiency of a well. If one or more of the well-completion components create a localized pressure drop, the effect may be a reduction in the production capability of the well. Such conditions are evident as completion skin.
Industry:Oil & gas
An indicator of the porosity that does not contribute to a sonic measurement of interval transit time. The transit time is little affected by vugs, fractures and other irregular events because the sonic wave finds a faster path around them. Spherical pores such as oomolds also have less effect on traveltime than oblate pores. Thus, when the sonic porosity is less than some measurement of the total porosity, the difference can be attributed to the presence of post-depositional, or secondary, porosity. The sonic porosity is usually derived from the Wyllie time-average equation, or some other suitable transform, and the total porosity taken as the density-neutron crossplot porosity.
Industry:Oil & gas
An in situ record of the capability of the fluid passing through a sensor to store electrical charge. Since water has a high dielectric constant, and hence capacitance, it can be distinguished from oil or gas. The capacitance, or fluid capacitance log, can therefore identify water and be scaled in terms of water holdup. However, the relation between capacitance and holdup depends strongly on whether the water is the continuous phase, complicating quantitative evaluation. <br><br>The log was introduced in the 1960s with the so-called holdup meter. It was mainly used in three-phase flow, or when fluid-density measurements were insufficiently sensitive to water at low holdup, or with heavy oils. Since the late 1980s, other holdup measurements have been preferred.
Industry:Oil & gas
An in situ record of casing thickness and integrity, to determine whether and to what extent the casing has undergone corrosion. The term refers to an individual measurement, or a combination of measurements using acoustic, electrical and mechanical techniques, to evaluate the casing thickness and other parameters. The log is usually presented with the basic measurements and an estimate of metal loss. It was first introduced in the early 1960s. Today the terms 鈥渃asing-evaluation log鈥?and 鈥減ipe-inspection log鈥?are used synonymously.
Industry:Oil & gas
An in situ log of the electrical potential on the inner wall of a casing. The log is used to identify intervals that are susceptible to corrosion. A negative slope in the profile indicates a zone in which current is leaving the casing and therefore acting as an anode. Such zones are susceptible to corrosion. The log was first introduced in the early 1960s. Modern logs are recorded with the tool stationary, and measure the potential difference and casing resistance between several pairs of sensors pushed against the casing wall, and between sensors and surface. <br>The log is usually represented with casing resistance and casing axial current. Sharp increases in casing resistance can indicate corroded zones or even holes in the casing. Decreasing axial current with depth indicates a corroding region.
Industry:Oil & gas
An in situ combustion technique in which only air or oxygen-enriched air mixtures are injected into a formation. A drawback related to dry combustion is the highly corrosive and noxious combustion products that are produced.
Industry:Oil & gas
An in situ combustion technique in which water is injected simultaneously or alternately with air into a formation. <br><br>Wet combustion actually refers to wet forward combustion and was developed to use the great amount of heat that would otherwise be lost in the formation. The injected water recovers the heat from behind the burning front and transfers it to the oil bank ahead. Because of this additional energy, the oil displacement is more efficient and requires less air. In spite of these advantages, a wet combustion process cannot avoid liquid-blocking problems and use of wet combustion is limited by the oil viscosity. <br><br>Wet combustion is also called in situ steam generation or a combination of forward combustion and waterflooding, which is abbreviated as COFCAW.
Industry:Oil & gas
An image of the external or internal features of a core. External images are photographs taken under natural or ultraviolet light; natural light highlights lithology and sedimentary structures, while ultraviolet light causes hydrocarbon zones to fluoresce. Internal images are obtained using X-rays or nuclear magnetic resonance (NMR). <br><br>X-ray techniques measure the attenuation of X-rays passing through the core. The attenuation depends mainly on the density. Hence the image reflects density and lithology changes, internal bedding planes, fractures and nodules. These techniques include, in increasing resolution, fluoroscopy, X-radiography and computed tomography. <br><br>Most NMR images measure the quantity and relaxation time of hydrogen, and therefore give information on fluid distribution. Some NMR techniques examine carbon, sodium and phosphorous.
Industry:Oil & gas
An extra curve on a log, designed to appear when the standard curve goes off track. For example, if the standard gamma ray curve is presented on a scale of 0 to 200 gAPI units, the backup curve may be scaled from 200 to 400 gAPI units. Alternatively, if the standard resistivity log is presented on a scale of 0 to 50 ohm-m, the backup curve might be presented on a scale of 0 to 500 ohm-m in the same track but be blanked off for readings below 50 ohm-m. The backup curve usually has the same coding as the standard curve but a different line weight.
Industry:Oil & gas
