Detecting Porosity & Permeability

Effective porosity can be measured with electromagnetic induction probes. Hydraulic conductivity can be measured in-situ by observing water-level fluctuations in drill-holes. For a system at equilibrium, the system needs to be disturbed to produce fluid flow by either pumping water out and observing the recharge rate, or injecting a slug of water and observing how quickly it dissipates out of the hole.

The purpose and environmental conditions of the test will impact what method is most appropriate. If permeability is being measured as part of contamination monitoring and modelling, the pumping or injection tests may further spread the contaminant. In some cases, it is best to substitute gas as the fluid, using equipment like the Core Laboratories Portable Probe Permeameter. The permeameter forces gas into an exposed rock face at a fixed initial pressure, then measures how quickly the gas dissipates into the outcrop as the pressure decays.

Borehole Logging

Flow zones may also be delineated through borehole surveys, usually involving temperature differentiation. A Temperature/Fluid Resistivity probe can be used to assess the temperature gradient, identify zones of variable water quality or salinity, and delineate features. An Impeller Flow Meter delineates water flow zones, while at a Heat Pulse Flow Meter can do the same thing but for lower flow rates.

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