Theoretical research of pressure propagation in pulsating hydraulic fracturing for coal permeability enhancement
by Yupeng Jiang; Huilin Xing
International Journal of Oil, Gas and Coal Technology (IJOGCT), Vol. 17, No. 1, 2018

Abstract: Pulsating hydraulic fracturing (PHF) technology has been regarded as one of the most effective method to improve both coal permeability and extraction rate of coal seam gas (CSG). However, proper theories for pressure loading and its propagation are still poorly understood, and thus the optimal fracturing conditions cannot be determined. In this paper, functions of pulsating pressure are analysed with the structure of pulsating apparatus and other engineering parameters. A positive correlation between pulsating frequency and loading pressure that observed in existing laboratory experiments is explained. Furthermore, an advanced mathematical approach is proposed and analytical/semi-analytical solutions are obtained to describe the law of pressure ripple propagation inside a loading pipe and coal cleat during fracturing progress. Finally, effects of both boundary conditions and crucial factors (e.g., length of loading pipe, pulsating frequency and injection scheme) on pressure changing pattern are analysed and discussed. The results demonstrated the usefulness of proposed algorithm for a better understanding of the basic mechanism and practical application of PHF technology in coal reservoirs. [Received: July 24, 2016; Accepted: February 27, 2017]

Online publication date: Fri, 19-Jan-2018

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