- Settore: Oil & gas
- Number of terms: 8814
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Related to a log of the resistivity of the flushed zone recorded by a wireline electrode device. The device is mounted on a pad and pressed against the borehole wall. Several designs exist, for example microlog, microlaterolog, proximity log, microspherical log and microcylindrical log. The microlog, being unfocused, is a more qualitative measurement. <br><br>The other measurements are focused. They try to minimize the effect of mudcake and rugose hole, while reading as short a distance as possible into the formation, to remain unaffected by the undisturbed zone. They are usually combined with a laterolog or induction log to correct the latter for the effects of invasion and for saturation determination in quick-look ratio methods. The logs are presented on a logarithmic scale from, for example 0. 2 to 2000 ohm-m.
Industry:Oil & gas
Referring to the change in temperature observed when a gas expands while flowing through a restriction without any heat entering or leaving the system. The change may be positive or negative. For each gas, there is an inversion point that depends on temperature and pressure, below which it is cooled and above which it is heated. For example, for methane at 100<sup>o</sup>C (212<sup>o</sup>F), the inversion point occurs at about 500 atmospheres (7350 psi). The magnitude of the change of temperature with pressure depends on the Joule-Thomson coefficient for a particular gas. <br><br>The Joule-Thomson effect often causes a temperature decrease as gas flows through pores of a reservoir to the wellbore.
Industry:Oil & gas
Regression techniques that find relationships between two or more variables that have a complex (nonlinear) relationship. Porosity and permeability relationships are often of this form in rocks that have multiple porosity types (primary, intergranular, fracture or vugular porosity, for example) or multiple cement types and other variables that affect permeability.
Industry:Oil & gas
Referring to the flow of two immiscible fluids, oil and water, oil and gas, or gas and water.
Industry:Oil & gas
Referring to the description of different regimes for the simultaneous flow of gas and liquid in vertical pipes introduced by Y. Taitel and A. Dukler in 1980. The results are shown in the form a crossplot or map with the superficial gas velocity, v<sub>gs</sub>, on the x-axis and the superficial liquid velocity, v<sub>ls</sub>, on the y-axis. Different maps are constructed for different pipe sizes and fluid properties. The Taitel-Dukler map defines the transition between different flow regimes more closely than other models. Taitel and Dukler also described flow transitions in horizontal pipes. <br><br>Reference:<br>Taitel Y, Barnea D and Dukler AE: 鈥淢odelling Flow Pattern Transitions for Steady Upward Gas-Liquid Flow in Vertical Tubes,鈥?AIChE Journal 26, no. 6 (May 1980): 345-354.
Industry:Oil & gas
Referring to an induction log made with a particular array of transmitter and receiver coils. The array was introduced in 1960 and became the industry standard for 30 years. The 6FF40 array has six coils with the main transmitter-receiver pair spaced 40 in. (102 cm) apart. The design of the array includes the spacing between the coils, the number of turns and the polarity of each coil. The three transmitter and the three receiver coils are each connected in series to produce one signal output. <br><br>FF means focused both radially and vertically. Unlike in an array tool, the focusing is fixed by the hardware design. The 6FF40 was designed to read deep into the formation while minimizing the signal close to the tool and maintaining reasonable vertical resolution. The 6FF40 was combined with a shallow electrode device to form the induction electrical survey. The use of both tools gave a qualitative indication of invasion. <br><br>Both the deep induction and the 6FF40 had deconvolution and a skin effect correction applied. The deconvolution was designed to reduce the effect of shoulder beds on the readings in high-resistivity beds. It was not effective in high-contrast formations. The skin effect correction was a simple exponential fit that would work on an analog computer.
Industry:Oil & gas
Referring to a type of spinner flowmeter in which most or all of the fluid flow in the well is diverted over the spinner by a device such as a basket or a packer.
Industry:Oil & gas
Referring to a type of conventional electrical log in which the current-emitting and the current-return electrodes (A and B) are placed close together on the sonde, with the measure electrode (M) several feet away and the measure return (N) far away. This arrangement is sensitive to the potential gradient between A and B. The spacing is defined by the distance from M to the midpoint between A and B. The most common spacing is 18 ft, 8 in. (5. 7 m). The lateral gives a sharper response to a bed boundary than a normal but also introduces several artifacts that can give misleading results.
Industry:Oil & gas
Referring to a type of conventional electrical log in which the current emitting electrode (A) and the measure electrode (M) are placed close together on the sonde, and the current return electrode (B) and the measure reference electrode (N) far away. The response is determined mainly by the distance between A and M. The larger AM, the deeper the measurement, but the poorer the bed boundary response. Although many distances have been used, the most common are 16 in. (40 cm), known as the short normal, and 64 in. (162 cm), known as the long normal.
Industry:Oil & gas
Referring to a log of the yields of different elements in the formation, as measured by capture gamma ray spectroscopy using a pulsed neutron generator. The log is a type of pulsed neutron spectroscopy log that uses only the capture spectrum. The capture spectrum is formed by many elements, but since the main purpose of the log is to determine lithology, the principal outputs are the relative yields of silicon, calcium, iron, sulfur, titanium and gadolinium. The yields give information only on the relative concentration of these elements. To get absolute elemental concentrations, it is necessary to calibrate to cores, or, more often, use a model such as the oxide-closure model. <br><br>The depth of investigation of the measurement is several inches into the formation. It can be run in open or cased hole. The absolute elemental concentrations are insensitive to fluids in the borehole and formation.
Industry:Oil & gas
