Lawrence Berkeley National Laboratory

Fracturing laboratory studies to support understanding of fracturing behavior in the field have been performed for more than six decades. These research studies have focused on various aspects of fracturing, including fracture orientation and borehole orientation with respect to the orientation of principal stresses, rock anisotropy, the effects of various types of discontinuities (also with respect to orientation), leak-off into the formation, fracturing fluid viscosity, and nontraditional methods. The studies have advanced in complexity and scale over the decades, with initial tests performed on very simple isotropic systems at the sub-15. cm scale, to very elaborate anisotropic natural and composed media at the near-meter scale. Studies have included laboratory-manufactured samples with known characteristics and natural samples with natural flaws. Although the potential experimental matrix of tests is very large and thus incompletely covered, the tests performed have provided much insight into subsurface fracturing behavior.