This combinable sonde is suitable for quantitative formation density measurements in uncased
holes. It uses a bottom loading gamma ray source (Typically 100 mCi activity) and a set of two
or optionally three detectors at different spacing to detect the gamma rays scattered by the
formation. The amount of scattered gamma rays is a function of the electron density of the
formation material and hence, a function of its bulk density. This relationship is used to calibrate
the density sonde and then use it to log the bulk density of the formations crossed by the
borehole. In order to optimise performance, the sonde is designed with three main features:
- A side-walling calliper to ensure that the detector measures only the radiation scattered by the formation.
A detector mandrel diameter that is large enough to minimise the sonde and borehole curvature mismatch and improve sonde to formation contact to minimise the effect of the borehole fluid.
An efficient detector shield to prevent gamma rays from travelling up, inside the sonde body.
A version of this tool including a short LL3 Guard Resistivity is also available. Please inquire.
Detectors: x2, NaI crystals Spaced at 47 and 25 cm (Opt. additional at 14 cm)
Source: 137Cs or 60Co
Max. Temp. 80ºC
Max. Press. 20MPa