Aramco Nano Permeameter ANP: A New Laboratory Technology for Accurate and Efficient Measurements of Stress-Dependent Source Rock Permeability

In an unconventional reservoir, rock matrix has a much larger storage capacity for hydrocarbon and significantly lower permeability than the natural and hydraulic fractures. It acts as a bottleneck for hydrocarbon flow from the reservoir to the production well during production and is a key parameter for controlling the well performance over a long period of time. A new laboratory technology is developed to accurately and efficiently measure the matrix permeability. We have developed the Aramco Nano Permeameter (ANP), a new laboratory technology for measuring the stress-dependent source rock permeability. While the conventional laboratory methods can only measure one permeability data point with one test run, ANP, based on the nonlinear solution to the gas flow equation, measures the rock matrix permeability for a non-fractured sample as a function of stress using a single test run and thus is very efficient. Permeability as a function of pore pressure at a given confining stress is measured with ANP for several Eagle Ford rock samples without fractures. The permeability curve shows complex behavior: permeability initially decreases with increasing pore pressure, as a result of Knudsen diffusion effect, and then increases with pore pressure owing to the mechanical deformation. The measured permeability curves are verified by comparing them with permeability values measured with other methods for selected pore pressures. The high measurement efficiency of ANP is also demonstrated. In summary, ANP is a laboratory method that is based on a theoretical idea that is significantly different from those currently used by the industry and thus provides a high measurement efficiency that the conventional methods cannot achieve.