Weight on bit downhole MWD sensors can measure weight-on-bit more accurately and transmit the data to the surface. Weight on bit Weight on bit (WOB), as expressed in the oil industry, is the amount of downward force exerted on the drill bit and is normally measured in thousands of pounds. Weight on bit is provided by drill collars, which are thick-walled tubular pieces machined from solid bars of steel, usually plain carbon steel but sometimes of nonmagnetic nickel-copper alloy or other nonmagnetic premium alloys. Gravity acts on the large mass of the collars to provide the downward force needed for the bits to
Atomic mass the averaged quantity atomic weight (see above), that is an average of values for many atoms in a given sample of a chemical element. Relative isotopic mass is similar to atomic mass and has exactly the same numerical value as atomic mass, whenever atomic mass is expressed in unified atomic mass units. The only difference in that case, is that relative isotopic mass is a pure number with no units. This loss of units results from the use of a scaling ratio with respect to a carbon-12 standard, and the word "relative" in the term "relative isotopic mass" refers to