The Research And Application Of The Direct Demodulation In Natural Gamma Ray Spectrum Logging

With the development of oil industry, the research of logging method plays a more and more important role in the development of well logging technology. Based on the existing logging tools, it is significant to adopt data-processing method with higher accuracy in order to improve the precision of logging by software. The aim of the thesis is to establish a new method with higher accuracy of nature gamma ray spectrum logging by using of Direct Demodulation (DD) which is effective to deal data with poor statistics and low signal-to-noise ratio. The main content of the thesis can be summarized in four points. First, we introduced the conventional methods of logging data processing in nature gamma ray spectrum logging and the basic idea, features and process of DD method. Secondly, we designed a scheme and compiled the procedures of it to carry out the DD method of nature gamma ray spectrum logging. Third, the response function of log instruments and the count rate of response function in the windows are calculated, and we calculated the background restrains in two different ways also. Fourthly, we dealt the data from the natural gamma ray spectrum logging calibration facilities of China Offshore Petroleum Logging Corporation. Besides, the results are compared with the standard results and the results calculated by conventional methods respectively. Our study proved that the DD method of nature gamma ray spectrum logging is an especially effective way to reduce statistical fluctuation.