Raptors - Birds of prey, such as hawks, falcons, and owls. 



Rat hole - A hole with casing that projects above the derrick floor, into 



which the kelly is placed when hoisting operations are in progress. 



Rectifier station - A small electrical apparatus that transforms alternating 

 current into direct current and simultaneously reduces the voltage 

 to a point where it generates a potential just strong enough to 

 protect the pipeline from the electrochemical characteristics of the 

 soil . 



Redox (also oxidation-reduction) - A chemical reaction in which one or more 

 electrons are transferred from one atom or molecule to another. 

 Corrosion of steel pipe or equipment is the result of an oxidation- 

 reduction reaction of iron to form ferric oxide. 



Reserve pit - A mud pit in which a reserve supply of drilling fluid is stored. 

 The "reserve pit" is actually used as a waste pit. 



Rhizome - A somewhat elongate usually horizontal subterranean plant stem that 

 is often thickened by deposits of reserve food material, produces 

 shoots above aiad roots below, and is distinguished from a true root 

 in possessing buds, nodes, and usually scale-like leaves. 



Round trip - To pull out, change bits, and subsequently run a complete string 

 of drill pipe back into the hole. 



Sacrificial anode - A piece of metal placed close to a steel pipe in the 



ground that, because of an electric or electrochemical potential, 

 selectively undergoes oxidation by chemical reaction with the soil. 

 The result is that the anode is oxidized rather than the pipe surface, 

 thus protecting the pipeline from corrosion. 



Scale - A hard incrustation usually rich in calcium sulfate that is deposited 

 on the inside of a vessel or pipe in which water is heated or trans- 

 ported. 



Scraper - A device used to clean deposits of paraffin from tubing or flowlines 

 (see pig ). 



Scrubber - Any of a number of devices that physically or chemically purify a 

 stream of gaseous materials flowing through them. 



Separator - A type of treatment apparatus that separates well fluids into 

 gases and liquids. 



Serai stages - Any one of a series of ecological communities that succeed one 

 another in the biotic development of an area. 



Shaker holding pit - A pit that contains the cuttings removed from the circu- 

 lating fluid stream by the shaker in rotary drilling operations. 



Slash - An open tract in a forest strewn with logging debris; also, the debris 

 (roots, branches, stumps, etc.) in such a tract. 



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