relative densityrelative permeabilityrelative viscosityreleasing socketreleasing spearrelief holerelief valveremovable packerremoval of cuttingsreplaceable cutterreplenishing valveresearch platformreserve mudreserve mud tankreserve pitreservoirreservoir boundaryreservoir capacityreservoir conditionsreservoir engineeringreservoir rockreservoir samplereservoir shutt offreservoir thicknessreservoir valuationreservoir voidagereservoir volume factorresidual oilresidual oil and brine saturationresidual water saturationresistance logresistance loggingresistance to flowresistivimeterresistivity gradientresistivity indexresistivity methodrestrictor valveretuberetubingreversal of dipreverse circulationreverse circulation bitreverse circulation subreverse combustionreversed spreversing valverich gasrig helperrig shift