- Industry: Oil & gas
- Number of terms: 8814
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A technique in nuclear magnetic resonance (NMR) logging that is based on the difference between the T<SUB>2</SUB> distributions, or spectra, acquired at different polarization times. The technique often is used to detect gas or light oil. These fluids have long T<SUB>1</SUB> that exceed 1 s. A measurement made with a long polarization time will polarize much of these fluids and give significant signal at the appropriate T<SUB>2</SUB>. A measurement made with a short polarization time will polarize little of these fluids and will give a much smaller signal. Other fluids, with shorter T<SUB>1</SUB>, will be polarized in both cases, so that a difference in signal at the appropriate T<SUB>2</SUB> identifies gas or light oil.
Industry:Oil & gas
A technique in nuclear magnetic resonance (NMR) logging based on a long echo spacing, specially chosen to enhance the diffusion of formation water. Echo spacings in standard NMR logs are too short to allow any significant diffusion relaxation from water. Long echo spacings, for example 3 s, cause diffusion relaxation to limit the maximum T<SUB>2</SUB> from water. They also limit the maximum T<SUB>2</SUB> from light hydrocarbons. However, there is a certain range of viscosity of medium oil that is less affected. The enhanced diffusion technique therefore permits the identification of some medium oils.
Industry:Oil & gas
Техника для использования фрактальной геометрии для получения описания водохранилище.
Industry:Oil & gas
Техника для полуколичественный минералогический анализ образец породы путем измерения дифракционных пиков в рентгеновских лучей, дифрагированных на образце. Положение дифракционных пиков является мерой расстояния между дискретных кристаллографических плоскостей Дифрагирующая в минералы, хотя их интенсивность указывает на количество минеральных. Техника только полуколичественный, потому что размер и форма пика дифракции сильно зависит от геометрии измерений, например ориентацию минералов и подготовки проб. Мелкие частицы, такие как глины должны быть отделены от более крупных частиц и измеряется отдельно, если они должны быть обнаружены должным образом. Для уменьшения количества ошибок, связанных с предпочтительной ориентации минералов, образцы наиболее часто молотый в порошок до анализа, метод, известный как порошковой дифракции рентгеновских лучей.
Industry:Oil & gas
A technique for recording the formation compressional slowness based on the transit time between transmitter and receiver. In the most basic wireline sonic measurement, an acoustic transducer emits a sonic signal, of between about 10 and 30 kHz, which is detected at two receivers farther up the hole. The time between emission and reception is measured for each receiver, and subtracted to give the traveltime in the interval between the two receivers. If the receivers are two feet apart, then this time is divided by two to give the interval transit time, or slowness, of the formation. This type of measurement is also known as first motion detection. <BR><BR>This technique works because the first arrival at the receiver is a wave that has traveled from the transmitter to the borehole wall, where it has generated a compressional wave in the formation. Some of this wave is critically refracted up the borehole wall, generating head waves in the borehole fluid as it progresses. Some of these strike the receiver, arriving in most cases well before any signal traveling directly through the mud. Furthermore, if the logging tool is parallel to the borehole wall, the traveltime in the mud is cancelled by taking the difference between the traveltime to the two receivers. Problems of irregular hole or a tilted tool are avoided by using borehole compensation. <BR><BR>The depth of investigation depends on the slowness, the transmitter-to-receiver spacing and the presence or absence of an altered zone. It is generally within the invaded zone, and of the order of several inches.
Industry:Oil & gas
Техника для записи звука на различных должностях в скважине для создания журнала, шум. Использует технику измерения микрофон для записи сигналов в слышимый диапазон приблизительно 20 000-20 000 Гц. В некоторых случаях частота сигнала можно отнести к источнику шума и режима потока, в то время как амплитуда сигнала может быть связана с скорость потока. Полезного сигнала лежит приблизительно между 100 и 5000 Гц, при более низких частотах, обычно представляющих фон и механических шумов. Измерение может записать всего сигнала за все частоты, сигнал на одной частоте, или состоят из набора измерений в различных частотных диапазонах.
Industry:Oil & gas
Техника для количественного минералогического анализа образец породы, измеряя влияние инфракрасного излучения СЧ через образец. Это излучение возбуждает колебания в химических связей в рамках полезных молекул на конкретных частотах характеристика каждой облигации. Передаваемые излучения сравнивается с спектральные стандартов для широкого спектра полезных ископаемых определить обилие каждого минерала в образце. Как правило основной штекер мелко перемалывается и репрезентативной выборки небольшой (примерно 1 г) выбирается и диспергированных в матрице бромистого калия для измерения.
Industry:Oil & gas
A technique for measuring the pore volume of a core sample from the difference in its weight when dry and when saturated with a liquid. A clean, dry sample is weighed and then evacuated for several hours in a vacuum chamber, flushing with CO<SUB>2</SUB> to remove remaining air if necessary. A de-aerated liquid is introduced into the chamber and pressured to ensure complete saturation. The saturated sample is then weighed again. The difference in weight divided by the density of the liquid is the connected, or effective, pore volume. <BR><BR>It is also common to measure the weight of the sample when immersed in the liquid. The grain and bulk volume can then be calculated as in the buoyancy method.
Industry:Oil & gas
A technique for measuring the fluid saturations in a core sample by heating the sample and measuring the volumes of water and oil driven off. The sample is crushed and weighed before being placed in the retort. It is then heated in stages or directly to 650<SUP>o</SUP>C (1200<SUP>o</SUP>F) during which the fluids are vaporized, collected, condensed and separated. Plateaus in the rise of the cumulative water volume with temperature are sometimes analyzed to indicate when free water, surface clay-bound water and interlayer clay-bound water have been driven off. <BR><BR>The volumes of water and oil are measured directly, but corrections are needed to account for alterations in the oil. The volume of gas also is needed for accurate results. This is measured on a separate, adjacent sample by injecting mercury under pressure and measuring the volume absorbed. Before injection, the sample is weighed and its bulk volume determined by mercury displacement. The total pore volume is then the sum of the volumes of gas, oil and water. The saturation of each component is the ratio of its volume to the total pore volume.
Industry:Oil & gas
A technique for measuring the effect of pits and holes in the inner wall of a casing on a high-frequency electrical signal induced in the casing. The eddy-current measurement is used in conjunction with a flux-leakage measurement to determine casing corrosion, the latter being sensitive to the defects on both the inner and outer walls. <BR>The principle of measurement is similar to the openhole induction log, but at higher frequencies. A transmitter coil produces a magnetic field that induces eddy currents in the casing wall. These currents generate their own magnetic field that induces a signal in two closely spaced receiver coils. In smooth casing, these signals are the same, but if the inner wall is pitted, the signals are different. Transmitter-receiver combinations are placed on multiple pads applied against the casing at several azimuths to fully cover the casing wall.
Industry:Oil & gas
