Method for correcting density measurements that are affected by natural and neutron-induced gamma radiation

摘要

A method for measuring formation density corrected for activated gamma radiation. The formation adjacent the borehole is irradiated with low energy gamma radiation from a density tool source. At least one gamma ray detection means is spaced longitudinally from the source. A gamma ray spectrum containing gamma rays that result from density source radiation and also activated gamma rays is detected by the detection means. The activated gamma rays are identified and subtracted from the total number of detected gamma rays which results in the gamma ray count from the density tool source. This gamma ray count can then be used in conventional density calculation processes to determine formation density that has been corrected for activated gamma rays caused by naturally occurring gamma radiation and from other logging equipment that induces gamma radiation.