Method and apparatus for rock property determination using pressure transient techniques and variable volume vessels

摘要

Method and apparatus for determining heterogeneous properties of a core sample by use of pressure transients. In the method, a pressure is applied to a first closed vessel at one end of a core sample. The pressure is then allowed to dissipate into the core and into a second closed vessel at the other end of the core sample. The pressure in at least one of the vessels or the core itself is measured and recorded as a function of time during the pressure dissipation. The volume of the first vessel is then varied and pressure is once again applied to the first vessel and allowed to dissipate into the core and second vessel. The pressure is again measured and recorded as a function of time during the pressure dissipation. The two sets of recorded measurements are then analyzed to detect deviations from theoretical responses in homogeneous cores which identify heterogeneities. Preferably, the volume of the first vessel has in either the first or second test a volume sufficiently small to cause a measurable variance between an actual pressure transient response for the system and a theoretical pressure transient response for the system. By using a small volume in both tests and reversing the direction of the second test, different heterogeneous properties may be detected.