A storage-type density meter for oil logging has been developed.It constitutes of a 137Cs source

a NaI scintillation detector

a pulse amplifier

a date storage circuit

a high voltage power supply and a Li ion battery

being integrated into a stainless steel container of Φ 60 mm × 1300 mm.Unlike density meters in current uses

this type of density meter goes into an oil well without an armored cable.Density data acquired in the well are stored for data analysis with a PC in laboratory.The density distribution derived from oil well can be a guide for oil exploration.Logging of the density meter can be done with only one crane

for a continuous logging of up to 15 days.