Oil & Gas Geology ›› 2013, Vol. 34 ›› Issue (1): 129-136.doi: 10.11743/ogg20130118

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Logging data normalization based on frequency spectral decomposition

Xiao Dianshi1, Lu Shuangfang1, Chen Haifeng1, Lu Yanping2, Li Zhandong1, Zhou Juan3   

  1. 1. Earth Sciences Institute, Northeast Petroleum University, Daqing, Helongjiang 163318, China;
    2. No.7 Production Plant, PetroChina Daqing Oilfield Company Ltd., Daqing, Helongjiang 163318, China;
    3. Logging Company, PetroChina Xibu Drilling and Engineering Company Ltd., Karamay, Xinjiang 834000, China
  • Received:2012-08-06 Revised:2012-12-31 Online:2013-02-28 Published:2013-03-18

Abstract:

Well log normalization can effectively reduce systematic errors during logging data interpretation,therefore has been used to improve the accuracy of formation parameter calculation and reservoir prediction.However,lack of a stable marker bed makes the marker-based normalization method too rigid to be adapted to continental sedimentary sequences with rapid variation of lithology.This paper analyzes the geological meaning of spectral decomposition,determines the contributions of different cycles to sedimentary formations,and then regards the superimposed formation of low-frequency cycles which represents the background values of formation as a macro marker bed with stable lateral distribution.The extreme value of low-frequency component was selected as characteristic value and the marker bed values were determined through trend surface analysis.Then translation correction and scale correction were carried out on the low-frequency and high-frequency components of the curves.Finally,log normalization can be achieved.This method had been applied to the normalization of logs of the Putaohua Formation in Daqing central uplift in Songliao Basin,and the correlation coefficient of core porosity and normalized curves was significantly higher than that of core porosity and original curves.This demonstrates that the log normalization method based on spectrum decomposition can be effectively applied to the continental sequences without stable marker beds.

Key words: well log, normalization, low-frequency cycle, spectral decomposition, reservoir evaluation, Daqing, central uplift, Songliao Basin

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