Methods for in-situ borehole seismic surveys using downhole sources

A method comprising:

• using microseismic events as seismic sources by inducing, via a lateral wellbore of a treatment well, at least one first microseismic event having a first spectral frequency content and inducing at least one second microseismic event having a second spectral frequency content;
• recording data relating to seismic waves generated by the microseismic events at at least one receiver positioned in a wellbore of a monitor well at a depth that is less than corresponding depths of the microseismic events wherein the at least one first microseismic event is closer to the at least one receiver than the at least one second microseismic event;
• and
• interpreting at least a portion of the seismic data for spectral power of the seismic waves generated by the microseismic events as located between the microseismic events and the at least one receiver, the interpreting comprising comparing the spectral power of the first spectral frequency content with the spectral power of the second spectral frequency content for qualitative information relating to hydrocarbon content based on hydrocarbon content diminishing spectral power.