Journal of Shanghai University(Natural Science Edition) ›› 2016, Vol. 22 ›› Issue (2): 246-260.doi: 10.3969/j.issn.1007-2861.2015.05.021

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Characteristics and pore structures of shale reservoir rocks in eastern and southeastern Chongqing of China

ZHU Yangsheng1,2, SONG Xuehang2, GUO Yintong3, XU Feng3, SUN Nannan2, WEI Wei2,4, CHEN Zhiwen1   

  1. 1. School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China;
    2. CAS Key Laboratory of Low-Carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201203, China;
    3. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China;
    4. School of Physical Science and Technology, Shanghai Tech University, Shanghai 201210, China
  • Received:2016-01-11 Online:2016-04-30 Published:2016-04-30

Abstract:

Elemental compositions, mineral compositions, reservoir space types and mechanical properties of shale samples from the Lower Silurian Longmaxi Formation and Lower Jurassic Ziliujing Formation were investigated by X-ray diffraction (XRD), gas adsorption (N2, CO2) analysis, field emission-scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), and uniaxial compressive tests. It was found that both formations arecharacterized by relatively high brittleness, high elastic modulus and lowPoisson’s ratio. That was advantageous for fracturing. To be more specific, each sample
was composed of quartz, clay, feldspar, calcite, dolomite, pyrite, berlinite and other minerals. In general, quartz content was higher than 45%, while clay content was relatively low(24.4%~32.5%), with chlorite, illite and kaolinite representing the major components. The SEM results indicated that pores could be classified into four types, namely intragranular pore, intergranular pore, organic matter pore and microfracture. In addition, the porosity of sample was 5% (capacity) with diameters mainly in the range of 0~20 nm.The BET specific surface areas and pore volumes were positively related to the total organic
carbon content (TOC) and clay content, while brittle minerals had a negative effect to these parameters.

Key words: correlation analysis,  Longmaxi Formation ,  pore structure,  shale reservoir ,  Ziliujing Formation , Chongqing district