The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 16, 1986
Filed:
Sep. 16, 1983
Chang Y Cha, Bakersfield, CA (US);
Thomas E Ricketts, Bakersfield, CA (US);
Occidental Oil Shale, Inc., Grand Junction, CO (US);
Abstract
A subterranean formation containing oil shale is prepared for in situ retorting by forming a fragmented permeable mass of formation particles containing oil shale in an in situ retort site. The retort is formed by excavating a lower level drift adjacent a lower portion of the retort site and excavating an upper level void adjacent an upper portion of the retort site. An undercut is excavated below a zone of unfragmented formation remaining within the retort site above the lower level drift. The undercut can be free of roof-supporting pillars. Explosive is loaded in the zone of formation from access provided by the upper void, and the zone of formation is blasted downwardly toward the undercut for forming the fragmented mass. The volume of the void space within the undercut prior to explosive expansion is similar to the void volume within the principal portion of the fragmented mass being formed. The zone of formation is blasted downwardly in lifts, with each lift being blasted toward a void space larger than a limited void, except for the last lift, which can be blasted toward a limited void. Blasting designs are also disclosed for providing reasonably uniform void fraction distribution in the fragmented mass.