The invention relates to a method for correcting natural
gamma ray spectral
logging of a barite mud well. At present, two methods, namely a five-
energy window least square method and a three-
energy window spectrum stripping method or a three-
energy window matrix method for unfolding spectrums and solving the content of
potassium,
uranium and
thorium of a formation are commonly adopted at home and abroad, and the precision of measuring the
potassium, the
uranium and the
thorium is low. The method comprises the following steps of: 1) transferring
logging to a lower level, namely when
gamma ray (GR) is more than 85API and the
layer thickness is more than 5m, performing five-energy window measurement; 2) performing three-energy window spectrum unfolding, and solving a two-low energy window correction coefficient by using the three-energy window spectrum unfolding; 3) lifting the
logging, solving a five-energy window
counting rate, and correcting a two-energy window correction coefficient; 4) determining whether the total GR is higher than 85 API or not, returning to the step (2) when the total GR is higher than 85 API and using the original coefficient for five-energy window spectrum unfolding when the total GR is lower than 85 API; and 5) acquiring K, U and Th of the formation by using the five-energy window spectrum unfolding. By the method, the formation
lithology can be correctly determined, and the precision of measuring the
potassium, the
uranium and the
thorium is high.