- Industry: Oil & gas
- Number of terms: 8814
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A numerical value used to analytically model the difference from the pressure drop predicted by Darcy's law due to skin. Typical values for the skin factor range from -6 for an infinite-conductivity massive hydraulic fracture to more than 100 for a poorly executed gravel pack. This value is highly dependent on the value of kh. For example, a 20-psi (138-kPa) total pressure drop related to skin effect could produce almost any skin factor, depending on the value of kh. For any given pressure drop from skin effect, the skin factor increases proportionally as kh increases.
Industry:Oil & gas
A numerical estimate of the chances of an event occurring given a limited number of opportunities for the event to occur.
Industry:Oil & gas
A non-thermal primary process for producing heavy oil, also called CHOPS. In this method, continuous production of sand improves the recovery of heavy oil from the reservoir. There is both a theoretical basis and physical evidence that, in many cases, wormholes are formed in the unconsolidated sand reservoir, thereby increasing oil productivity. In most cases, an artificial lift system is used to lift the oil with sand.
Industry:Oil & gas
A nipple that incorporates a reduced diameter internal profile that provides a positive indication of seating by preventing the tool or device to be set from passing through the nipple. In many completions, a no-go landing nipple is preferred for the deepest nipple location, providing a no-go barrier to protect against a tool string being run or dropped below the tubing string.
Industry:Oil & gas
A neutron porosity log recorded while the well is flowing to determine the gas-oil contact in the borehole. The log is often compared with a log run while the well is shut-in. The term was used in the1950s and 1960s but is now obsolete.
Industry:Oil & gas
A neutron porosity log in which the effects of the borehole environment are minimized by using two detectors. In the most common technique, the two source-detector spacings are chosen so that the ratio of the two count rates is relatively independent of the borehole environment. This ratio is then calibrated in terms of porosity in a known formation and borehole environment typically with the tool placed against the side of an 8-in. (20-cm) borehole in a limestone block, both filled with fresh water at surface temperature and pressure. The response is also determined at different porosities and in sandstones, dolomites and other borehole environments. Correction factors are developed to convert the measured log to the standard conditions. <br><br>The source and detectors are not azimuthally focused. Wireline tools are run eccentralized against the borehole wall. Since the neutrons emitted into the mud are strongly attenuated, the resulting log is effectively focused into the formation. Measurements-while-drilling tools will normally be unfocused since they are centralized unless the borehole is overgauge. <br><br>The vertical resolution is about 2 ft (0. 6 m), but can be improved by alpha processing.
Industry:Oil & gas
A near-wellbore formation zone, a few inches thick, whose acoustic velocity has been affected by impregnation with drilling fluids, stress relief, or both. The acoustic velocity of the rock in the immediate vicinity of the borehole wall can be much slower than that in the virgin formation. To measure the formation velocity, it may be necessary to use a sonic logging tool that has a greater spacing between transmitter and receiver array (about 10 to 15 ft (3 to 4. 5 m)) than the standard sonic tool (about 3 to 5 ft (0. 9 to 1. 5 m)). The altered zone may also give rise to different acoustic modes, for example the hybrid mode or a second Stoneley wave.
Industry:Oil & gas
A neutron interaction in which part of the kinetic energy lost by a neutron in a nuclear collision excites the nucleus. The excited nucleus will usually emit characteristic gamma rays upon de-excitation. Inelastic neutron scattering is possible only if the neutron energy exceeds a characteristic threshold for the element. Inelastic neutron scattering is the principle behind the carbon-oxygen log, which is used to determine water saturation behind casing.
Industry:Oil & gas
A neutron interaction in which the neutron is absorbed by the target nucleus, producing an isotope in an excited state. The activated isotope de-excites instantly through the emission of characteristic gamma rays. Neutron capture, also called thermal capture, usually occurs at low thermal energies at which the neutrons have about the same energy as the surrounding matter, typically below 0. 4 eV (0. 025 eV at room temperature). Some elements are better thermal absorbers than others. Neutron capture is an important principle behind the pulsed neutron capture log, the elemental capture spectroscopy log, the pulsed neutron spectroscopy log and the thermal neutron porosity measurement.
Industry:Oil & gas
A neutron interaction in which the neutron is absorbed by the target nuclei, which then emit nuclear particles such as alpha or beta particles, gamma rays, protons or additional neutrons. Fast neutron reactions have a small probability of occurrence relative to the other principal interactions, except at high neutron energy.
Industry:Oil & gas
