Laboratory Study of Microseismicity Caused by Pore Pressure Increase

Results of laboratory study of microseismicity relation with pore pressure increase are considered. Spatial-temporal correlation between microseismic emission and pore pressure change was studied under different stress states: stiff-confined loading and “soft”-confined loading. It was found, that in case of water injection a front of AE propagation corresponds to propagation of pore pressure change. In experiments with “soft”-confined loading propagation of AE corresponds to pore pressure increase up to values approximately equal to uniaxial unconfined compression strength (which depends on porosity of the sample). In experiments with “soft”-confined loading the value of pressure for AE starting is smaller and approximately equal to 0.2 – 0.4 of compression strength. The velocity of AE front propagation depends approximately linear on the sample permeability.<br><br>The results can be used for estimation of a reservoir average strength and permeability and for correct interpretation of passive seismic monitoring data during hydro fracturing<br>