Shale Porosity and Permeability

Shale porosity and permeability are key factors for shale oil and gas.

Permeability is a critical parameter of tight reservoir rocks that determine their viability for commercial development. For these unconventional reservoir rocks, fast, accurate, and routine determination of permeability is essential. Current methods for measuring permeability may lead to erroneous results when applied to very tight gas shale. Picture 4 is Ultra low permeability analysis apparatus for shales. The specifications are as follows:

Pore pressure: between 30 and 2000 psi

Stress or confining pressure: up to 10,000 psi

Permeability Range: 0.000001 md To 10 md (Depending on sample size)

Perm Measurement Method: Pulse Decay

Core Sample size : Length: 0.5 to 2.0 inch

Diameter : 1.0 inch and 1.5 inch

True Tri-axial core-holder (capability of all core-holder)

Differential Pressure Setting: 0 to 100 psi

Pressure Transducer Accuracy: 0.1%Fs

Optional: Automatic confining pressure pump

Max Working Pressure: 10,000 psi

Pump Speed: 0.0001 to 80 ml/min

Volume: 250 ml

Material: 316SS

Accuracy: 0.1%FS

It can control by panel touch screen, and PC software.

The porosity is based on the Boyle’s and Charles’ law expansion of helium gas and is used for direct grain volume and poro volume measurement in auxiliary cell at isothermal conditions. Subsequently, porosity and gain density can be derived from the direct measurements.
When we do the matrix permeameter model, a shale sample is crushed and sieved between 20 to 35 US Mesh screens to yield a sample with a diameter between 0.5 mm to 0.853 mm. Approximately 30 to 50 grams of this crushed and sieved sample is placed into the test chamber of the S-Poro 200 (Picture 4). Helium, at approximately 200 psig, is then expanded into the test chamber. The pressure decline curve is then recorded for 5 to 30 minutes. A simulator history match of the pressure decline curve then yields the matrix permeability of the shale sample.