APPARATUS AND METHOD FOR MEASURING FORMATION DENSITY IN RUGOSE BOREHOLES

摘要

A method and apparatus for determining the density of a formation traversed by a borehole operates by: (i) lowering into the borehole a sonde having a resilient member, the member being equipped with a backscatter detection device having a photon source, a detector, and a substantially small contact head; (ii) urging the member towards the borehole wall facing the contact head; (iii) positioning the contact head on the borehole wall; (iv) irradiating the formation with photons from the source; (v) detecting photons scattered by the formation using the detector; (vi) generating count rate signals responsive to the photons detected by the detector; and (vii) processing the count rate signals to derive the density of the formation. The photon source may be an x- ray generator, radioscopic, or other source. The detector may include a cadmium zinc telluride crystal. Methods and apparatus for calibration are also provided.