Effect of Stress on Permeability of Coal.

摘要

The permeabilities of three types of bituminous coals were measured under several stress conditions which were to simulate possible states of stress in underground environments to depths of 2,000feet. Nitrogen and methane were flowed in the axial direction through 2-inch-diameter by 3-inch-length specimens. The few radial tests that were run agreed favorably with the axial flow tests. Sonic velocities were measured concurrently with permeability tests,and dynamic and static deformation moduli and bulk and pore compressibilities were determined. The study found that the permeabilities of different samples of the same coal varied over a wide range,that permeabilities decreased by one to two orders of magnitude with increasing stress,and that the permeability of coal is very dependent on previous loading and unloading of the sample.