Use of perforation shot S wave attenuation to constrain locations of hydraulic fractures in the Marcellus Shale

Water filled open fractures created by hydraulic fracturing will severely attenuate S waves. By comparing with the P and S wave amplitude generated by perforation shots in the Marcellus Shale, we are able to infer the existence and constrain the location of stimulated and probably propped hydraulic fractures. The waveform of the perforation shots in unstimulated virgin shale was first analyzed to check the radiation pattern. Then we present two cases in which the change of perforation shot S wave waveform reveals information about the hydraulic fractures. In case 1 we used S wave attenuation to validate the existence of an offstage hydraulic fracture. In case 2 we show an example of invasion of frack fluid from another neighbor stage identified from S wave attenuation. This method can be potentially used to design cross well survey to better monitor the hydraulic fracturing results.