**Acknowledgements**

proposed that these characteristic are those which should be chosen as the defining charac‐ teristic for a terminology to differentiate between different "types" of hydraulic fracturing with

An obvious approach would be to use the terms, mini-frac, midi-frac, macro-frac, etc, however the term mini-frac is already in use for both stress testing and for conventional and uncon‐ ventional oil and gas. Alternatively, to use, for example, Class 1, 2, 3, etc, is in danger of being

It is suggested that a practical approach may be to rely on a "Typing" system such as that

**Type A** – no actual new fractures created though exisiting fractures are opened and possibly washed out. This Type would apply to water well hydraulic fracturing and such geotechnical tests as hydro-jacking. As this is an "outlier" with no real fracture occurring it is felt unnecessary to specify the injected volume though it would be typically less than 10,000 litres.

**Type B** – new fractures are generated but little or no attempt is made to propagate these fractures. Examples would include stress testing and rock burst amelioration. Injected fluid

**Type C** – new fractures are generated and some attempt is made to propagate these fractures. Typically injected fluid volumes per fracture are to be limited to less than, say 100,000 litres per fracture. Hydraulic fracturing for block caving, CMM and possibly CBM would fall into this category. Given that these may also include proppant and or additives in the injected fluids some additional nomenclature is appropriate to account for these additions. In an attempt to

**Type D** – new fractures are generated and these are propagated to the size required to produce the stimulation desired. Typically injected fluid volumes per fracture are more than, say 100,000 litres per fracture. Most CBM, conventional and multi-zonal, unconventional hydraulic fracturing would fit into this category. This Type would also use the suffix notation given

Hydraulic fracturing is a process used in many industries for different applications and purposes. It may be characterized and differentiated across this range of industries in terms

volume is to be limited to less than a few hundred litres per fracture.

injected volume taking the primary role.

398 Effective and Sustainable Hydraulic Fracturing

described below.

keep it simple, this could be:

Type C-a – water with additives

Type C-p – water with proppant

Type C-ap – water with additives and proppant

above for Type C to further specify the injected fluids.

of injected volume and the composition of the injected fluids.

Type C – plain water

**5. Conclusions**

confused with the USEPA well classification system.

The authors wish to acknowledge and express appreciation for the contribution of our reviewer, Rob Jefferies, to the correctness and completeness of this paper.

### **Author details**

Joel Adams1\* and Clem Rowe2\*

\*Address all correspondence to: joel@inflatable-packers.com; clem@inflatable-packers.com

1 Inflatable Packers International LLC, Australia

2 Inflatable Packers International Pty Ltd, Australia

#### **References**


**Chapter 19**

**Initiation and Breakdown of an Axisymmetric Hydraulic**

We investigate the initiation and early-stage propagation of an axi-symmetric hydraulic fracture from a wellbore drilled in the direction of the minimum principal stress in an elastic and impermeable formation. Such a configuration is akin to the case of a horizontal well and a hydraulic fracture transverse to the well axis in an open hole completion. In addition to the effect of the wellbore on the elasticity equation, the effect of the injection system compressi‐ bility is also taken into account. The formulation accounts for the strong coupling between the elasticity equation, the flow of the injected fluid within the newly created crack and the fracture propagation condition. Dimensional analysis of the problem reveals that three di‐ mensionless parameters control the entire problem: the ratio of the initial defect length over the wellbore radius, the ratio between the wellbore radius and a length-scale associated with the fluid stored by compressibility in the injection system during the well pressurization, and finally the ratio of the time-scale of transition from viscosity to toughness dominated propagation to the time-scale associated with compressibility effects. A fully coupled nu‐ merical solver is presented, and validated against solutions for a radial hydraulic fracture propagating in an infinite medium. The influence of the different parameters on the transi‐ tion from the near-wellbore to the case of a hydraulic fracture propagating in an infinite me‐

In this study, we are interested in the initiation of hydraulic fractures from an open-hole horizontal well. Horizontal wells are drilled preferably in the direction of the minimum

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

© 2013 Abbas and Lecampion; 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 Transverse to a Horizontal Wellbore**

Safdar Abbas and Brice Lecampion

http://dx.doi.org/10.5772/56262

dium is fully discussed.

**1. Introduction**

**Abstract**

Additional information is available at the end of the chapter

