putting radioactive charge in wireline string
locked case radioactive source logging job
nuclear tools measure formation properties through interaction of reservoir molecules radiation emitted logging tool. 2 common properties measured nuclear tools formation porosity , rock density:
formation porosity determined installing radiation source capable of emitting fast neutrons downhole environment. pore spaces in rock filled fluid containing hydrogen atoms, slow neutrons down epithermal or thermal state. atomic interaction creates gamma rays measured in tool through dedicated detectors, , interpreted through calibration porosity. higher number of gamma rays collected @ tool sensor indicate larger number of interactions hydrogen atoms, , larger porosity.
most open hole nuclear tools utilize double-encapsulated chemical sources.
density tools use gamma ray radiation determine lithology , density of rock in downhole environment. modern density tools utilize cs-137 radioactive source generate gamma rays interact rock strata. since higher density materials absorb gamma rays better lower density materials, gamma ray detector in wire line tool able accurately determine formation density measuring number , associated energy level of returning gamma rays have interacted rock matrix. density tools incorporate extendable caliper arm, used both press radioactive source , detectors against side of bore , measure exact width of bore in order remove effect of varying bore diameter on readings.
some modern nuclear tools use electronically powered source controlled surface generate neutrons. emitting neutrons of varying energies, logging engineer able determine formation lithology in fractional percentages.
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