Characterization of Hydraulic Fracturing in the Marcellus Shale using Microseismic Data
Tan, Yunhui; Zhou, Rongmao; Engelder, Terry; Maxwell, Shawn; Mueller, Mike; Thornton, Michael P.
The objective of this study is to understand and characterize hydraulic fracturing at the Marcellus level through detailed analysis of microseismic events during hydraulic fracturing of four laterals drilled in southwest Pennsylvania. The technique for this analysis was the inversion and decomposition of the seismic moment tensor for the larger microseismic events. 34 out of the 50 largest events identified from a downhole linear array of Schlumberger accelerometers were processed by Microseismic Inc. using data from their surface array. Lower frequency and better spatial coverage made surface array data a better source for performing moment tensor inversion. Inversion was done based on a linear relationship between seismic moment tensor and P-wave first motion using a L2-norm inversion algorithm.
11 of the 34 events took place on subvertical plane with a subvertical slip vector. The average strike of the nodal planes from these subvertical events was N49°E. Some of these subvertical events had a relatively large volumetric component whereas other events were mainly double couple. Dip-slip motion is consistent with the majority of regional stress data from the eastern edge of the North American continental lithosphere. The subvertical orientation of these brittle fractures is most consistent with the J1 joint set populating black shale of the Appalachian Basin.
AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013