Multl-stage fracture injection process for enhanced resource production from shales

摘要

The invention relates to a method of generating an enhanced fracture network in a rock formation by the sequential stages of: i) injecting a non-slurry aqueous solution into a well extending into the formation at a rate and pressure which is close to the minimum hydraulic fracture initiation pressure and rate of the formation, until the maximum possible stimulated volume of the formation has been substantially attained to generate an outer zone of self-propping fractures; ii) injecting a first slurry of relatively fine grains of proppant to prop fractures generated in stage i within an intermediate zone located within and surrounded by the outer zone generated in stage i; and iii) injecting a second slurry comprising relatively coarse grains of to generate large fractures within an inner zone surrounded by and within the intermediate zone, in communication with the fractures generated in stages i and ii.