Distribution of a water film confined in inorganic nanopores in real shale gas reservoirs

Distribution of the water film and initial water saturation within inorganic nanopores of shale are key problems for the evaluation and prediction of recoverable gas resources. Numerous research on the distribution and quantitative characterization of water film confined in nanopores have been conducted to the present. However, quantitation of water confined in inorganic nanopores of shale gas reservoir still remains challenging due to the complexity of porous media and reservoir conditions. In the present study, a novel model with disjoining pressure, interfacial tension and real gas effect taken into consideration, was proposed to disclose the distribution of water film confined inside circular or elliptic pores. In addition, the phenomena of capillary condensation and partial condensation have been revealed in elliptic pores. The proposed model was verified by comparing the calculation results with data from previous paper. Results show that the capillary condensation behavior of the water film is remarkably affected by the real gas effect. Water condenses easily into water films under the actual gas reservoir conditions, especially for small pores. However, the interfacial tension and high temperature can inhibit the formation of the water film in the confined space at a nanometer scale. Finally, the partial condensation is more likely to occur at both ends of elliptic pores.

Automated summary

This study proposed a novel model to reveal the distribution of water film confined inside circular or elliptic pores in shale, considering disjoining pressure, interfacial tension, and real gas effect. The phenomena of capillary condensation and partial condensation were observed, and the model was verified by comparing with previous data.