- Industry: Oil & gas
- Number of terms: 8814
- Number of blossaries: 0
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The reduced or total absence of fluid flow up the annulus when fluid is pumped through the drillstring. Though the definitions of different operators vary, this reduction of flow may generally be classified as seepage (less than 20 bbl/hr (3 m<sup>3</sup>/hr)), partial lost returns (greater than 20 bbl/hr (3 m<sup>3</sup>/hr) but still some returns), and total lost returns (where no fluid comes out of the annulus). In this severe latter case, the hole may not remain full of fluid even if the pumps are turned off. If the hole does not remain full of fluid, the vertical height of the fluid column is reduced and the pressure exerted on the open formations is reduced. This in turn can result in another zone flowing into the wellbore, while the loss zone is taking mud, or even a catastrophic loss of well control. Even in the two less severe forms, the loss of fluid to the formation represents a financial loss that must be dealt with, and the impact of which is directly tied to the per barrel cost of the drilling fluid and the loss rate over time.
Industry:Oil & gas
The ratio of the actual output volume of a positive displacement pump divided by the theoretical geometric maximum volume of liquid that the pump could output under perfect conditions. Inefficiencies are caused by gaseous components (air and methane) being trapped in the liquid mud, leaking and noninstantaneously sealing valves in the pumps, fluid bypass of pump swab seals, and mechanical clearances and "play" in various bearings and connecting rods in the pumps. This efficiency is usually expressed as a percentage, and ranges from about 92% to 99% for most modern rig pumps and cement pumps. For critical calculations, this efficiency can be determined by a rigsite version of the "bucket and stopwatch" technique, whereby the rig crew will count the number of pump strokes required to pump a known volume of fluid. In cementing operations, displacement is often measured by alternating between two 10-bbl displacement tanks.
Industry:Oil & gas
The quality of a source rock that makes it more likely to generate oil than gas. The nature of the organic matter (kerogen) in source rocks varies from coaly, plant-like material commonly found in terrestrial source rocks to algal or other marine material that makes up marine source rocks. Marine source rocks are commonly oil-prone.
Industry:Oil & gas
The quality of a source rock that makes it more likely to generate gas than oil. The nature of the organic matter or kerogen in source rocks varies from coaly, plant-like material commonly found in terrestrial source rocks to algal or other marine material that makes up marine source rocks. Terrestrial source rocks are commonly gas-prone.
Industry:Oil & gas
The pumpability or consistency of a slurry, measured in Bearden units of consistency (Bc), a dimensionless quantity with no direct conversion factor to more common units of viscosity.
Industry:Oil & gas
The product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates. Portland cement is the most common type of cement used for oil- and gas-well cementing.
Industry:Oil & gas
The process whereby steel components become less resistant to breakage and generally much weaker in tensile strength. While embrittlement has many causes, in the oil field it is usually the result of exposure to gaseous or liquid hydrogen sulfide (H<sub>2</sub>S). <br><br>On a molecular level, hydrogen ions work their way between the grain boundaries of the steel, where hydrogen ions recombine into molecular hydrogen (H<sub>2</sub>), taking up more space and weakening the bonds between the grains. The formation of molecular hydrogen can cause sudden metal failure due to cracking when the metal is subjected to tensile stress. <br><br>This type of hydrogen-induced failure is produced when hydrogen atoms enter high strength steels. The failures due to hydrogen embrittlement normally have a period where no damage is observed, which is called incubation, followed by a sudden catastrophic failure. <br><br>Hydrogen embrittlement is also called acid brittleness.
Industry:Oil & gas
The process whereby steel components become less resistant to breakage and generally much weaker in tensile strength. While embrittlement has many causes, in the oil field it is usually the result of exposure to gaseous or liquid hydrogen sulfide (H<sub>2</sub>S). On a molecular level, hydrogen ions work their way between the grain boundaries of the steel, where hydrogen ions recombine into molecular hydrogen (H<sub>2</sub>), taking up more space and weakening the bonds between the grains. The formation of molecular hydrogen can cause sudden metal failure due to cracking when the metal is subjected to tensile stress.
Industry:Oil & gas
The process of separating components of a slurry by leaving the suspended solids as filter cake on a filter medium while the liquid passes through. The process can be either static or dynamic.
Industry:Oil & gas
The process of removing water from water-base drilling mud. Dewatering can involve chemical treatment for the flocculation and aggregation of solids followed by mechanical separation, such as centrifugation, or mechanical treatments alone.
Industry:Oil & gas
