- Industry: Oil & gas
- Number of terms: 8814
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A technique for elemental analysis of samples based on the characteristic fluorescence given off by different elements subjected to X-rays. In core analysis, X-ray fluorescence often is used to help determine mineral content. The elemental volumes are inverted to mineral volumes by assuming certain standard formulae for mineral composition.
Industry:Oil & gas
A technique for determining the velocity of fluid flow in an injection well based on measuring the time a slug of radioactive tracer takes to move down the well. The analysis is usually performed as part of a tracer-loss measurement. The depth of the slug is measured by running repeated gamma ray logs at well-defined time intervals. From the differences in depth and time, the velocity can be determined.
Industry:Oil & gas
A technique for determining the deviation of a wellbore. The multishot tool provides more accuracy than the single-shot tool and is usually used in highly deviated wells.
Industry:Oil & gas
A technique for combining a measurement that has a high accuracy but low precision with another measurement of the same quantity that has a high precision but low accuracy in order to produce a result that is better than either alone. Alpha processing is used to improve the vertical resolution of neutron porosity and other dual-detector nuclear logs. The detector near the source has better precision than the far detector in the sense that it responds more precisely to vertical changes. However, the near detector is less accurate because it is more affected by the borehole environment. Alpha processing mathematically superimposes the rapid changes of the near detector on the slowly changing but accurate far detector to produce an accurate log with high vertical resolution. <br><br>The technique is also used to improve results from the carbon-oxygen log and other pulsed neutron spectroscopy measurements. Two methods are used to determine the carbon/oxygen ratio. The windows method counts the number of gamma rays within energy windows placed at the main peaks for carbon and oxygen. This method has good statistical precision but poor accuracy, as gamma rays from other elements contaminate these windows. The other method, spectral stripping, compares the total spectrum against standards for many elements, inverting the spectrum to obtain the yield for each element. This method is more accurate but has less statistical precision. Averaging over a number of measurements, alpha processing adjusts the windows result with the more accurate spectral stripping in order to obtain a precise and accurate result.
Industry:Oil & gas
A technique for cleaning core samples in which the water fraction is removed by distillation and the oil fraction is extracted using solvents. Cleaning is done with either the Soxhlet or, when fluid saturation measurements are required, the Dean-Stark apparatus. Different solvents are used depending on the type of fluids and rock, the most common ones being toluene, methanol, xylene and chloroform. Several solvents may be used in sequence.
Industry:Oil & gas
A technique for analyzing the grain-size distribution of a core sample. A cleaned, disaggregated sample is dispersed in a carrier fluid. The grains cause diffraction of a laser beam directed through the fluid. The angle of scattering is inversely proportional to the particle size, while the intensity of scattering is proportional to the number of particles. Laser diffraction also may be referred to as laser sieve analysis.
Industry:Oil & gas
A technique for acquiring deviation information from a borehole on a slickline. In high-angle wells, a multishot technique is usually used instead.
Industry:Oil & gas
A tank designed for storing volatile liquids such as gasoline and liquefied petroleum gases (LPG), which generate high internal pressures. A pressure storage tank is commonly spherical. Other types include spheroidal or hemispherical vessels. Some pressure storage tanks can support several hundred pounds per square inch of internal pressure. A pressure storage tank is also called a pressure-type tank.
Industry:Oil & gas
A table that shows the tank capacity in barrels as a function of the liquid level inside the tank. A tank table is also called a tank capacity table or gauge table.
Industry:Oil & gas
A systems tract overlying a sequence boundary and overlain by a transgressive surface. Characterized by a progradational to aggradational parasequence set, this systems tract commonly includes a basin-floor fan, a slope fan and a lowstand wedge. It is often abbreviated as LST.
Industry:Oil & gas
