**5. Summary**

Microseismic monitoring is a very useful tool for optimizing fracture treatments, evaluating completion schemes, and assessing well layouts and spacing in unconventional reservoirs. The microseismicity is induced by the reservoir changes resulting from the hydraulic fracturing process. The dimensions and orientation of the fracture can usually be deduced from the microseismic distribution, and it is often possible to determine other features of the fracturing process, such as complexity, asymmetry, and interaction with geohazards.

[2] Batchelor, A. S, Baria, R, & Hearn, K. Monitoring the Effects of Hydraulic Stimulation by Microseismic Event Location: A Case Study. SPE 12109 In: SPE Annual Technical

Understanding Hydraulic Fracture Growth, Effectiveness, and Safety Through Microseismic Monitoring

http://dx.doi.org/10.5772/55974

133

[3] Hart, C. M, Engi, D, Fleming, R. P, & Morris, H. E. Fracture Diagnostic Results for the First Multiwell Experiment's Paludal Zone Stimulation. SPE Formation Evaluation.

[4] Warpinski, N. R, Branagan, P. T, Sattler, A. R, Cipolla, C. L, Lorenz, J. C, & Thorne, B. J. Case Study of a Stimulation Experiment in a Fluvial Tight Sandstone Gas Reser‐

[5] Branagan, P. T, Peterson, R, Warpinski, N. R, & Wright, T. B. The Characterization of Remotely Intersected Set of Hydraulic Fractures: Results of Intersection Well GRI/DOE Multi-Site Project. SPE 36452 In: SPE Annual Technical Conference and Ex‐

[6] Warpinski, N. R, Branagan, P. T, Peterson, R. E, Fix, J. E, Uhl, J. E, Engler, B. P, & Wilmer, R. Microseismic and Deformation Imaging of Hydraulic Fracture Growth and Geometry in the C Sand Interval, GRI/DOE M-Site Project. SPE 38573 In: SPE Annual Technical Conference and Exhibition, October, (1997). San Antonio, Texas.,

[7] Branagan, P. T, Warpinski, N. R, Peterson, R. E, Hill, R. E, & Wolhart, S. L. Propaga‐ tion of a Hydraulic Fracture into a Remote Observation Wellbore: Results of C-Sand Experimentation at the GRI/DOE M-Site Project. SPE 38574 In: SPE Annual Technical

[8] Warpinski, N. R, Branagan, P. T, Peterson, R. E, & Wolhart, S. L. An Interpretation of M-Site Hydraulic Fracture Diagnostic Results. SPE 39950 In: SPE Rocky Mountain Regional/Low Permeability Reservoirs Symposium, April, (1998). Denver, Colorado.,

[9] Walker, R. N, Zinno, R. J, Gibson, J. B, Urbancic, T, & Rutldge, J. Carthage Cotton Valley Fracture Imaging Project-Imaging Methodology and Implications. SPE 49194 In: SPE Annual Technical Conference and Exhibition, September, (1998). New Or‐

[10] Rutledge, J. T, Phillips, W. S, & Mayerhofer, M. J. Faulting Induced by Forced Fluid Injection and Fluid Flow Forced by Faulting: An Interpretation of Hydraulic-Fracture Microseismicity, Carthage Cotton Valley Gas Field, Texas. Bulletin of the Seismologi‐

[11] Peterson, R. E, Warpinski, N. R, Lorenz, J. C, Garber, M, Wolhart, S. L, & Steiger, R. P. Assessment of the Mounds Drill Cuttings Injection Disposal Domain. SPE71378 In: SPE Annual Technical Conference and Exhibition, 30 September-3 October, (2001).

Conference and Exhibition, October, (1997). San Antonio, Texas., 5-8.

Conference and Exhibition, October, (1983). San Francisco, California., 5-8.

voir. SPE Production Engineering. (1990). , 5(4), 403-410.

hibition, October, (1996). Denver, Colorado.(1), 6-9.

(1987). , 2(3), 320-326.

5-8.

5-8.

leans, Louisiana., 27-30.

New Orleans, Louisiana.

cal Society of America (2004). , 94(5), 1817-1830.

It is important to understand the geomechanical process that occurs during fracturing to best interpret the microseismic distribution and to fully understand the value of any source analyses, such as moment tensor inversion. The perturbations imparted to the reservoir during fracturing are usually very large and can result in unexpected behaviour, if ignored.

Microseismicity monitoring has provided a very large data base from which environmental impacts of fracturing can be assessed. With thousands of fractures monitored, there is clear evidence that fractures do not extend the thousands of feet vertically to the shallow depths of typical aquifers. Fractures are generally much longer than they are tall as a result of the rock mechanic barriers that result from sedimentary structures.

Microseismicity monitoring has also provided evidence that hydraulic fractures are not likely to generate felt earthquakes in anything other than the rarest circumstances. Most of the seismic activity induced by a hydraulic fracture has energy levels that are 1,000 to 1,000,000 times smaller than events that would be felt at the surface, and even much farther below those that might cause damage.
