- Industry: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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A type of milling operation in which the outer surfaces of a plug or similar fish are milled with a circular hollow mill. By including wash pipe in the tool string, the mill face can reach over the body of the fish until it can be pushed to bottom, or until the slips or retaining device can be milled out and the fish retrieved.
Industry:Oil & gas
A type of mechanism commonly used in the setting and unsetting of downhole tools and equipment such as packers. Most conventional downhole tools operate by upward or downward movement, rotation, or a combination of both. The J-slot profile creates the track for an actuating cam or pin that combines rotation and up or down movement to provide a simple yet reliable means of tool activation.
Industry:Oil & gas
A type of logging while drilling density log in which the density is measured at different azimuths around the drill collar. The density measurement is focused, so that when the collar rotates, the measurement sees different azimuths around the borehole. An average density can be calculated by summing all the azimuthal data. Alternatively, the data can be summed over different segments, for example in four quadrants, to give an azimuthal density in four directions. When the hole is overgauge, certain quadrants will be firmly pressed against the borehole wall, while others may have a significant standoff and too high a delta rho. The good quadrants can then be chosen for formation evaluation.
Industry:Oil & gas
A type of lock designed to be set in the recess of a tubing collar. Collar locks are compatible only with conventional thread connections where a space exists between the two tubing joints. Premium tubing grades have flush internal surfaces with no space to enable setting of the retaining dogs.
Industry:Oil & gas
A type of landing nipple designed to be run in a series throughout the wellbore. Two basic types of selective nipple system may be encountered, a nipple series in which the nipple design or profile determines the selectivity and one in which the running tool is used to find the target nipple.
Industry:Oil & gas
A type of jar that incorporates a mechanical trip or firing mechanism that activates only when the necessary tension or compression has been applied to the running string. In slickline operations, the term is often used to describe any jar that does not contain a hydraulic trip mechanism, such as link and tubular jars that do not incorporate a firing mechanism.
Industry:Oil & gas
A type of in-situ combustion in which the burning front moves in an opposite direction to the injected air. Initially, air is injected into a production well and the fire is ignited. After the burning front has advanced some distance from the production well, air is supplied only near the injection well. The burning front advances toward the injection well while the oil moves toward the production well. <br><br>Reverse combustion actually refers to dry reverse combustion and can be used to recover extremely viscous oil or tar. In reverse combustion, the liquid blocking problem is solved because a hot zone is maintained near the production well. Despite this advantage, this process is not as efficient as dry forward combustion because lighter fractions of the oil are burned and heavier fractions are left behind the burning front. Another drawback is the possibility of a spontaneous ignition in the injector well, which will divert air for combustion near the injector well instead of near the producer.
Industry:Oil & gas
A type of in situ combustion in which the burning front moves in the same direction as the injected air. As air is continuously supplied at the injection well, the fire ignited at this location moves toward the production wells. <br><br>During forward combustion, the temperature behind the burning front is high, indicating a great amount of heat stored in the formation matrix. The injected gas heats on contact with the matrix and recovers only a small amount of the heat, with considerable losses to the surrounding formations. Another drawback of dry forward combustion is the presence of a highly viscous oil zone surrounding the production well. The fluid in this zone remains at the original reservoir temperature and its forward displacement by the heated oil is normally difficult.
Industry:Oil & gas
A type of inhibition treatment used to control or prevent scale deposition. In a scale-inhibitor squeeze, the inhibitor is pumped into a water-producing zone. The inhibitor is attached to the formation matrix by chemical adsorption or by temperature-activated precipitation and returns with the produced fluid at sufficiently high concentrations to avoid scale precipitation. Some chemicals used in scale-inhibitor squeezes are phosphonated carboxylic acids or polymers.
Industry:Oil & gas
A type of high-specification fluid filter frequently used to remove small solid particles from workover or treatment fluids that may be injected into, or placed adjacent to, the reservoir formation. In using absolute filters, all particles larger than the micron rating of the filter element in use will be removed from the treated fluid.
Industry:Oil & gas
