Quantitative evaluation method and application of wettability of shale multi-scale storage space

The quantitative evaluation of the wettability of shale multi-scale reservoir space is the basis for efficient shale oil development. In this paper, firstly, innovative quantitative evaluation method and application for the wettability of shale multi-scale storage space is studied. Secondly, a quantitative evaluation method for the multi-scale reservoir space wettability of the Gulong shale and the impact of external fluids on the wettability of the Gulong shale is established. Thirdly, the interfacial tension between different types of injection media and shale oil under different temperature and pressure conditions is clarified. Results show that: (a) The effect of external fluids on improving the overall hydrophilicity of shale (change in water oil ratio) is ranked as follows: GJ surfactant (0.06) > guanidine gum (0.03) > slick water (-0.01); (b) The effect of external fluids on improving the hydrophilicity of pores in shale (water oil ratio change value) is ranked as follows: GJ surfactant (0.80) > guanidine gum (0.24) > slick water (0.19); (c) Under geological conditions, the interfacial tension between the injected medium and shale oil is 0-0.3 mN/m: GJ surfactant (0.018), alkaline solution (0.142), GJ surfactant + acid solution (volume ratio 2:1) (0.195), and alkylbenzene sulfonate solution (0.263).