Method of bulking an in situ oil shale retort substantially full of fragmented shale

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, the subterranean formation comprising an upper level base of operation at an elevation above the retort, the upper level base of operation having a sufficient horizontal cross section for providing effective access over substantially the entire horizontal cross section of the fragmented permeable mass being formed, the method comprising the steps of:

• excavating formation to form at least one substantially horizontal void in the retort site in the subterranean formation, such as subterranean formation providing a sill pillar of unfragmented formation above such a void and a zone of unfragmented formation within the retort site adjacent such a void;
• explosively expanding at least a portion of such a zone of unfragmented formation toward such a void, thereby forming a first fragmented permeable mass of formation particles in the in situ retort and leaving a void space between the upper surface of a first fragmented permeable mass of formation particles and the bottom surface of the sill pillar of unfragmented formation;
• and
• explosively expanding a bottom portion of the sill pillar toward such a void space for forming a second fragmented permeable mass of formation particles substantially filling the void space and the volume occupied by the bottom portion of the sill pillar for at least partly supporting the sill pillar for maintaining the structural integrity of the sill pillar.

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, the subterranean formation comprising an upper level base of operation at an elevation above the retort, the upper level base of operation having a sufficient horizontal cross-section for providing effective access over substantially the entire horizontal cross-section of the fragmented permeable mass being formed, the method comprising the steps of:

• excavating formation to form at least one substantially horizontal void in the retort site in the subterranean formation, such a subterranean formation providing a sill pillar of unfragmented formation above such a void and a zone of unfragmented formation within the retort site adjacent such a void;
• explosively expanding at least a portion of such a zone of unfragmented formation toward such a void for forming a principal portion of the fragmented permeable mass of formation particles, there remaining a void space of greater than about three feet in height between the surface of the principal portion of the fragmented permeable mass of formation particles and an interim bottom surface of the sill pillar of unfragmented formation;
• and thereafter
• explosively expanding a bottom portion of the sill pillar downwardly toward the void space, forming a minor portion of the fragmented permeable mass of formation particles, there remaining no more than about three feet in height of void space between the upper surface of the minor portion of formation particles and the final bottom surface of the sill pillar.

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

• excavating an upper level base of operation at an elevation above the elevation of the top boundary, the upper level base of operation having a sufficient horizontal cross-section for providing effective access over substantially the entire horizontal cross-section of the fragmented permeable mass being formed;
• excavating a first portion of formation for forming at least one void within the boundaries of the retort being formed and leaving a remaining portion of formation within the boundaries adjacent such a void;
• explosively expanding such a remaining portion toward such a void for forming a first fragmented permeable mass of formation particles in the retort, there being a void space between the upper surface of the first fragmented permeable mass and overlying unfragmented formation below the floor of the base of operation;
• explosively expanding a bottom portion of the overlying formation downwardly toward the void space for providing a second fragmented permeable mass of formation particles, such a second fragmented permeable mass of formation particles substantially filling such a void space and the volume occupied by said bottom portion and leaving a horizontal sill pillar of unfragmented formation between the top boundary and the overlying base of operation for providing a barrier between the base of operation and the retort during retorting operations.

A method of recovering liquid and gaseous products from an in situ oil shale retort in a subterranean formation, the in situ retort containing a fragmented permeable mass of formation particles containing oil shale, such an in situ retort having a top boundary, generally vertically extending side boundaries, and a bottom boundary of unfragmented formation, the method comprising the steps of:

• excavating an upper level base of operation at an elevation above the elevation of the top boundary, the upper level base of operation having a sufficient horizontal cross-section for providing effective access over substantially the entire horizontal cross-section of the fragmented permeable mass being formed;
• excavating a first portion of formation for forming at least one void within the boundaries and leaving a remaining portion of formation within the boundaries adjacent such a void;
• explosively expanding such a remaining portion toward such a void for forming a first fragmented permeable mass of formation particles in the retort, there being a void space between the upper surface of the first fragmented permeable mass and overlying unfragmented formation below the floor of the base of operation;
• explosively expanding a lower portion of such overlying formation downwardly toward the void space for providing a second fragmented permeable mass of formation particles, such a second fragmented mass of formation particles substantially filling such void space and the volume occupied by the lower portion of such overlying formation and leaving a horizontal sill pillar of unfragmented formation between the top boundary and the overlying base of operation;
• introducing an oxygen containing gas into the retort from the upper level base of operation for establishing a retorting zone in the fragmented permeable mass of formation particles wherein oil shale is retorted to produce gaseous and liquid products, and for advancing the retorting zone through the fragmented permeable mass;
• and
• withdrawing the gaseous and liquid products from the retort.

A method for recovering gaseous and liquid products from an in situ oil shale retort in a retort site in a subterranean formation containing oil shale, and in situ oil shale retort containing a fragmented permeable mass of formation particles containing oil shale within top, bottom, and generally vertically extending side boundaries of unfragmented formation, the method comprising the steps of:

• excavating formation to form at least one substantially horizontal void in the subterranean formation, the subterranean formation comprising an upper zone of unfragmented formation above such a void and a lower zone of unfragmented formation below such a void;
• explosively expanding unfragmented formation from at least one of the zones of unfragmented formation toward the void, thereby forming a principal portion of the fragmented permeable mass of formation particles in the in situ oil shale retort and leaving a void space between the upper surface of such a principal portion of the fragmented mass and the bottom surface of remaining unfragmented formation overlying the void space;
• thereafter explosively expanding a plurality of horizontally spaced apart bottom portions of such remaining overlying unfragmented formation downwardly toward the void space, for forming a minor portion of the fragmented permeable mass of formation particles in the in situ retort, the minor portion of the fragmented mass being in contact with a plurality of regions of the bottom surface of such overlying unfragmented formation for supporting the overlying formation while void spaces remain between the minor portion of the fragmented mass and other regions of the bottom surface of such overlying unfragmented formation;
• introducing oxygen-supplying gas into the in situ oil shale retort for establishing a combustion zone and a retorting zone in the fragmented permeable mass, and for advancing the combustion zone and retorting zone downwardly through the fragmented mass, thereby retorting oil shale to produce liquid and gaseous products;
• and
• withdrawing such liquid and gaseous products from the retort.

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

• excavating a first portion of formation from within a retort site for forming at least one substantially horizontal void within the retort boundaries and leaving a remaining portion of formation within the retort boundaries adjacent such a void;
• explosively expanding such a remaining portion of formation toward the void for forming a first fragmented permeable mass of formation particles in the retort, there being a void space between the upper surface of the first fragmented permeable mass and overlying unfragmented formation;
• and
• explosively expanding a plurality of horizontally spaced apart lower portions of such overlying formation downwardly toward the void space for providing a second fragmented permeable mass of formation particles, the second fragmented mass of formation particles being in contact with a plurality of regions of the bottom surface of remaining overlying formation while void spaces remain between the second fragmented mass of formation particles and other regions of such remaining overlying formation.

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

• excavating formation from within the retort site for forming at least one substantially horizontal void within the retort boundaries, while leaving at least one zone of unfragmented formation within the retort boundaries adjacent such a void;
• placing a plurality of horizontally spaced apart explosive charges in such a zone of unfragmented formation and detonating the explosive charges for expanding formation toward the void to thereby form a first fragmented permeable mass of formation particles in the retort, a void space being between the upper surface of the first fragmented permeable mass and overlying unfragmented formation;
• and
• placing a plurality of horizontally spaced apart explosive charges in a lower portion of such overlying unfragmented formation and detonating the explosive charges for explosively expanding overlying formation downwardly toward the void space for providing a second fragmented permeable mass of formation particles in the retort, the second fragmented permeable mass being in contact with a plurality of regions of the bottom surface of remaining overlying formation while void spaces remain between the second fragmented mass and other regions of such remaining overlying formation.