**Author details**

Norm R. Warpinski

Pinnacle—A Halliburton Service, Houston, Texas, USA

#### **References**

[1] Albright, J. N, & Pearson, C. F. Acoustic Emissions as a Tool for Hydraulic Fracture Location: Experience at the Fenton Hill Hot Dry Rock Site. Society of Petroleum Engi‐ neers Journal. (1982). , 22(4), 523-530.

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

**5. Summary**

132 Effective and Sustainable Hydraulic Fracturing

might cause damage.

**Acknowledgements**

**Author details**

Norm R. Warpinski

**References**

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

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

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

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

[1] Albright, J. N, & Pearson, C. F. Acoustic Emissions as a Tool for Hydraulic Fracture Location: Experience at the Fenton Hill Hot Dry Rock Site. Society of Petroleum Engi‐

fracturing are usually very large and can result in unexpected behaviour, if ignored.

process, such as complexity, asymmetry, and interaction with geohazards.

mechanic barriers that result from sedimentary structures.

The author thanks Halliburton for permission to publish this paper.

Pinnacle—A Halliburton Service, Houston, Texas, USA

neers Journal. (1982). , 22(4), 523-530.


[12] Fisher, M. K, Wright, C. A, Davidson, B. M, Goodwin, A. K, Fielder, E. O, Buckler, W. S, & Steinsberger, N. P. Integrating Fracture Mapping Technologies to Optimize Stimulations in the Barnett Shale. SPE Production & Facilities. (2005). , 20(2), 85-93.

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[25] Agarwal, K, Mayerhofer, M. J, & Warpinski, N. R. Impact of Geomechanics on Micro‐ seismicity. SPE152835 In: SPE/EAGE European Unconventional Resources Confer‐ ence and Exhibition, March, (2012). Vienna, Austria., 20-22.

[12] Fisher, M. K, Wright, C. A, Davidson, B. M, Goodwin, A. K, Fielder, E. O, Buckler, W. S, & Steinsberger, N. P. Integrating Fracture Mapping Technologies to Optimize Stimulations in the Barnett Shale. SPE Production & Facilities. (2005). , 20(2), 85-93. [13] Maxwell, S. C, Urbancik, T. I, Steinsberger, N. P, & Zinno, R. Microseismic Imaging of Hydraulic Fracture Complexity in the Barnett Shale. SPE77440 In: SPE Annual Technical Conference and Exhibition, 29 September-2 October, (2002). San Antonio,

[14] Pearson, C. The Relationship between Microseismicity and High Pore Pressure Dur‐ ing Hydraulic Stimulation Experiments in Low Permeability Granitic Rocks. Journal

[15] Warpinski, N. R, Wolhart, S. L, & Wright, C. A. Analysis and Prediction of Microseis‐

[16] Aki, K, & Richards, P. G. Quantitative Seismology, 2nd Edition. University Science

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[19] Nasseri MHBThompson B., Schubnel A., and Young RP. Acoustic Emission Monitor‐ ing of Mode I Fracture Toughness (CCNBD) Test in Lac du Bonnet Granite. ARMA/ USRMS In: 40th US Symposium on Rock Mechanics. 25-29 June, (2005). Anchorage,

[20] Chitrala, Y, Sondergeld, C. H, & Rai, C. R. Acoustic Emission Studies of Hydraulic Fracture Evolution Using Different Fluid Viscosities. ARMA In: 46th US Rock Me‐ chanics/Geomechanics Symposium., 24-27 June, (2012). Chicago, Illinois., 12-597. [21] Warpinski, N. R, Mayerhofer, M. J, Agarwal, K, & Du, J. Hydraulic Fracture Geome‐ chanics and Microseismic Source Mechanisms. SPE158935 In: SPE Annual Technical

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134 Effective and Sustainable Hydraulic Fracturing


**Section 2**

**Naturally Fractured Reservoirs 1**

**Naturally Fractured Reservoirs 1**

**Chapter 7**

**Development of Fracture Networks Through Hydraulic**

A 2-D numerical study was carried out, using a fully coupled rock deformation and fluid flow hydraulic fracturing model, on fracture network formation by advancing, widening and interconnecting discrete natural fractures in a low-permeability rock, some of which are small enough to be considered as a flaw that acts as a fracture seed. The model also includes fractures connecting into one another to form a single hydraulic fracture. In contrast to previous fracture network models, fracture extension and fluid flow behavior, frictional slip, and fracture interaction are all explicitly addressed in this model. Incompressible Newtonian fluid is injected at a constant total rate into fractures to study viscous fluid effects on the network formation. The algorithm for flow division and coalescence is validated through some

Numerical results show that the incremental crack propagation that connects isolated natural fracture sets depends on the current stress state and the fracture arrangement. The newly created connecting fracture segments increase local conductivity since they are oriented along a path that is easier to open when pressurized by fluid and provide a new path for fluid flow. However the hydraulic fracture growth process is retarded by some of the resulting geometric changes such as intersections and offsets, and the growth-induced sliding that can impose a barrier to further fracture growth and fluid flow into parts of the network. Such barriers may eventually result in a fracture branch initiating and growing that results in a relatively shorter

We consider a specific fracture arrangement consisting of around 20 conductive pre-existing fractures to study the effective behavior of the hydraulic fracture growth through a natural fracture network. Mechanical responses have been studied for two different fracture and flow scenarios depending on the fluid entry details: one fracture system assumes each of four entry

and reproduction in any medium, provided the original work is properly cited.

© 2013 Zhang and Jeffrey; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2013 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

**Fracture Growth in Naturally Fractured Reservoirs**

Xi Zhang and Rob Jeffrey

http://dx.doi.org/10.5772/56405

**Abstract**

examples.

Additional information is available at the end of the chapter

and more conductive path through a fracture network zone.
