Method for loading explosive laterally from a borehole

A method of forming an in situ fragmented permeable mass of formation particles within a subterranean formation, the in situ fragmented permeable mass of formation particles having a top boundary, side boundaries, and a bottom boundary of unfragmented formation, the method comprising the steps of:

• (a) excavating formation to form at least one void in the subterranean formation, leaving zones of unfragmented formation adjacent such a void, within the top boundary, side boundaries, and bottom boundary of the fragmented permeable mass being formed, such a zone of unfragmented formation having a free face adjacent the void;
• (b) forming at least one main blasthole in such a zone of unfragmented formation;
• (c) placing at least one explosive charge shaped for forming a high velocity gas and fragment jet into such a main blasthole with the axis of the high velocity gas and fragment jet extending transverse to the main blasthole;
• (d) detonating such a shaped charge for forming an auxiliary blasthole in unfragmented formation adjacent a side wall of the main blasthole, wherein such an auxiliary blasthole is in communication with the main blasthole and extends away from the main blasthole;
• (e) placing explosive into the main blasthole and into such an auxiliary blasthole;
• and
• (f) detonating the explosive for explosively expanding formation toward such a free face for forming the in situ fragmented permeable mass of formation particles.

A method of forming an in situ oil shale retort in a retort site within a subterranean formation containing oil shale, such an in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale and having a top boundary, side boundaries, and a bottom boundary of unfragmented formation, the method comprising the steps of:

• (a) excavating formation to form at least one void in the subterranean formation, leaving zones of unfragmented formation adjacent such a void within the boundaries of the retort site, such a zone of unfragmented formation having a free face adjacent the void;
• (b) forming at least one main blasthole in such a zone of unfragmented formation;
• (c) placing at least one explosive charge shaped for forming a high velocity gas jet into such a main blasthole with the axis of the gas jet extending transverse to the main blasthole;
• (d) detonating such a shaped charge for forming an auxiliary blasthole in unfragmented formation adjacent a side wall of the main blasthole, wherein such an auxiliary blasthole is in communication with the main blasthole and extends away from the main blasthole;
• (e) placing explosive into the main blasthole and into such an auxiliary blasthole;
• and
• (f) detonating the explosive for explosively expanding formation towards such a free face for forming the fragmented permeable mass of formation particles in the in situ oil shale retort.

The subterranean formation containing oil shale in an intermediate stage of preparation of an in situ oil shale retort having a top boundary, side boundaries, and a bottom boundary of unfragmented formation comprising:

• (a) at least one void in the subterranean formation;
• (b) at least one zone of unfragmented formation adjacent such a void, such a zone of unfragmented formation having a free face adjoining the void;
• (c) an array of main columnar explosive charges in such a zone of unfragmented formation;
• (d) at least one auxiliary columnar explosive charge in communication with such a main columnar explosive charge, wherein such an auxiliary columnar explosive charge is in communication with a main columnar explosive charge adjacent a side boundary of such an in situ oil shale retort being formed and has an axis parallel to such adjacent side boundary;
• and
• (e) means for detonating such explosive charges for explosively expanding unfragmented formation toward such a free face.

A method of forming an in situ oil shale retort in a retort site within a subterranean formation containing oil shale, such as in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale and having a top boundary, side boundaries, and a bottom boundary of unfragmented formation, the method comprising the steps of:

• (a) excavating formation to form at least one void in the subterranean formation, leaving zones of unfragmented formation above and below such a void, such a zone of unfragmented formation having a substantially horizontal free face adjoining the void;
• (b) forming an array of vertically extending columnar explosive charges in such a zone of unfragmented formation, such an array generally parallel to the substantially horizontal free face;
• (c) forming at least one laterally extending columnar explosive charge in communication with such a vertically extending columnar explosive charge, and extending laterally from such a vertically extending columnar explosive charge;
• and
• (d) detonating such explosive charges for explosively expanding formation towards such a horizontal free face for forming a fragmented permeable mass of formation particles in the in situ oil shale retort.