Dynamic strength of oil shale. [Effects of pressure, strain rate, and kerogen and calcite content on shale strength]

Journal Article · Sun Feb 01 04:00:00 EST 1976 · Soc. Pet. Eng. J.; (United States)

DOI:https://doi.org/10.2118/5327-PA· OSTI ID:7268062

Lankford, J Jr

In-situ retorting of oil shale requires explosive loading under overburden pressure to break up rock masses. Therefore, a study of the dynamic, confined failure strength under compressive loading was carried out for shale ranging in kerogen content from 11 to 45 gal/ton. It was found that the envelope of ultimate strength could be described by a first-order failure criterion that expands uniformly in principal stress space about the hydrostatic axis as the strain rate increases. The strength/log-strain-rate dependence was found to be nonlinear, with the strength doubling over seven orders of magnitude in strain rate. In these laboratory tests, considerable ductility at failure was encountered, with the strain at failure ranging from 2 to 35 percent. Failure strength was ordered consistently with respect to kerogen content, but the strength-reducing presence of large calcite inclusions in the leanest grade of shale overcame the effect of lower kerogen content to the extent that specimens of intermediate richness exhibited the highest strength.

• Research Organization: Southwest Research Inst., San Antonio
• OSTI ID: 7268062
• Journal Information: Soc. Pet. Eng. J.; (United States), Journal Name: Soc. Pet. Eng. J.; (United States) Journal Issue: 01 Vol. 16:1; ISSN SPTJA
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040500* -- Oil Shales & Tar Sands-- Properties & Composition
ALKALINE EARTH METAL COMPOUNDS
BITUMINOUS MATERIALS
CALCITE
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONACEOUS MATERIALS
CARBONATES
COMPRESSION STRENGTH
DESTRUCTIVE TESTING
ENERGY SOURCES
FOSSIL FUELS
FRACTURE PROPERTIES
FUELS
KEROGEN
MATERIALS TESTING
MECHANICAL PROPERTIES
OIL SHALES
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
STRESSES
TESTING