5/19/2006 flow in fractured reservoirs and influence the seal capacity of reservoir bounding faults (Chapter 11). Before discussing rock strength, it is helpful to start with a clear definition of terms and common test procedures which are illustrated in Figure 4-1.
Figure 4-1 - The most common types of rock mechanics tests. While it is common for petrophysical properties to be measured as a function of hydrostatic pressure, strength is typically measured via either uniaxial or triaxial tests. As discussed in the text, triaxial extension and polyaxial tests are rare. Pore pressure is frequently an independent variable in these tests by using a flexible, impermeable sleeve outside the sample. For obvious reasons, pore pressure is not used in uniaxial tests. It is also not used in polyaxial tests because of the experimental difficulty of sealing pressure within the samples.
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