Oil & Gas Geology ›› 2019, Vol. 40 ›› Issue (3): 550-557.doi: 10.11743/ogg20190310

• Petroleum Geology • Previous Articles     Next Articles

Determination of the starting time for measurement of NMR effective porosity in shale oil reservoir: A case study of the Permian Lucaogou shale oil reservoir,Jimusaer sag

Wang Wei1, Zhao Yanwei2, Mao Rui1, Sun Zhongchun1, Mu Liwei1   

  1. 1. Exploration and Development Research Institute of Xinjiang Oilfield Branch Company, PetroChina, Karamay, Xinjiang 834000, China;
    2. No.1 Oil Production Plant, Xinjiang Oilfield Branch Company, PetroChina, Karamay, Xinjiang 834000, China
  • Received:2019-02-12 Revised:2019-03-26 Online:2019-06-28 Published:2019-04-26

Abstract: Due to the fine-grained lithology and complex pore throat structure of the Lucaogou shale oil reservoir in Jimusaer sag,Junggar Basin,it is difficult to accurately calculate the effective porosity by conventional logging interpretation methods.To solve this difficulty,30 sandstone samples of five clay types were selected for measurements such as porosity under helium expansion,nuclear magnetic resonance (NMR) T2 spectrum under different conditions,type and content of clay.The mechanism of clay type effect on short lateral relaxation component of reservoir NMR T2 signal was revealed through the analysis of matching experimental data.Subsequently,combined with the experimental results and the NMR relaxation time of bound water in various clay types,the effective porosity of shale oil reservoirs in the study area was calculated accurately by iteration method.The initial NMR time was determined to be 1.7 ms,which have been verified well by core analysis and actual logging.The study serves as a new technical solution for effective porosity evaluation of shale oil reservoir.

Key words: NMR logging, clay mineral, effective porosity, shale oil, Lucaogou Formation, Permian, Jimusaer sag, Junggar Basin

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