- A Numerical Investigation of Fault Slip Triggered by Hydraulic Fracturing
- N. Zangeneh ; E. Eberhardt ; R.M. Bustin ; A. Bustin
- Book Title / Journal: Effective and Sustainable Hydraulic Fracturing
- Year: 2013 , Series: Chapter 23
- Numerical & Constitutive Modeling ; Mining
- Keywords: numerical investigation ; hydraulic fracturing ; shale gas reservoirs
- Description
- The study of fault slip in response to fluid injection offers a means to understand the complex hydromechanical behavior of shale gas and oil reservoir systems during hydraulic fracturing operations, together with the induced seismicity, and corresponding mitigation measures, arising from such events. In this paper, a series of numerical simulations are performed to investigate the relationship between hydraulic fracturing (i.e. fluid injection) and the response of a naturally fractured rock mass to transient fluid pressures. The analysis is carried out using the discontinuum-based distinct-element program UDEC assuming a fracture flow system. The conceptual reservoir model consists of a critically stressed fault plane and the surrounding rock mass containing planes of weakness, for which a hydraulic fracture is numerically simulated and the response modeled using a transient, coupled hydro-mechanical solution. The results demonstrate the influence of fluid diffusion generated by the fracing fluid after shut-in on the triggering of fault slip. The simulation is then used to interpret the associated seismic events and their relationship to the injections and shut-in pressures, and to estimate the maximum magnitude of the induced seismic event.
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- Blue Shift in the Spectrum of Arrival Times of Acoustic Signals Emitted during Laboratory Hydraulic Fracturing
- A.V. Dyskin ; E. Pasternak ; A.P. Bunger ; J. Kear
- Book Title / Journal: Effective and Sustainable Hydraulic Fracturing
- Year: 2013 , Series: Chapter 22
- Laboratory Testing
- Keywords: hydraulic fracturing ; acoustic signals
- Description
- We discuss a method of detecting localised fracturing that potentially requires only one
channel. The method is based on the notion that the fracture propagation involves generation
of acoustic events from its contour. It is proposed that the number of events (microcracks) generated at each step of fracture propagation could be proportional to the fracture size to a certain power called the localisation exponent. This dependence of the number of generated events on the fracture size (the event coherence) leads to a shift to higher frequency (the “blue shift”) in the combined spectrum of the events as compared to the spectrum of randomly generated events. This concept was applied to the results of a laboratory test in which hydraulic fracture was driven by injecting glycerine into a 200x200x120mm block of polycrystalline gabbro. We show that there is indeed a blue shift in the spectrum of the arrival times at any one sensor that seems to correspond with the growth of a localized hydraulic fracture. The localisation exponent is able to distinguish between the cases of the fracture contour length roughly proportional to, and more slowly than proportional to, the nominal fracture radius.
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- Microseismic Monitoring Developments in Hydraulic Fracture Stimulation
- M. van der Baan ; D. Eaton ; M- Dusseault
- Book Title / Journal: Effective and Sustainable Hydraulic Fracturing
- Year: 2013 , Series: Chapter 21
- Instrumentation ; Mining
- Keywords: microseismic monitoring ; hydraulic fracturing
- Description
- The last decade has seen a significantly increased interest in microseismic monitoring by the hydrocarbon industry due to the recent surge in unconventional resources such as shale-gas
and heavy-oil plays. Both hydraulic fracturing and steam injection create changes in local pore pressures and in situ stresses and thereby brittle failure in intact rock plus additional slip/shearing in naturally fractured rock. Local rock failure or slip yields an acoustic emission, which is also known as a microseismic event. The microseismic cloud represents thus a volumetric map of the extent of induced fracture shearing, opening and closing. Microseismic monitoring can provide pertinent information on in situ reservoir deformation due to fluid stimulation, thus ultimately facilitating reservoir drainage. This paper reviews some of the current key questions and research in microseismicity, ranging from acquisition, processing to interpretation.
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- Differentiating Applications of Hydraulic Fracturing
- J. Adams ; C. Rowe
- Book Title / Journal: Effective and Sustainable Hydraulic Fracturing - Chapter 18
- Year: 2013
- Rock Mechanics ; Other Geotechnical
- Keywords: hydraulic fracturing ; rock stress measurements
- Description
- Hydraulic fracturing has received abundant media attention in recent years due to a rapid increase in the use of the technique in combination with horizontal drilling technology to produce oil and gas resources from tight reservoirs. Hydraulic fracturing techniques are also used in a variety of other applications that are unrelated to oil and gas production, including tunnel and dam construction, enhanced geothermal energy, carbon sequestration, groundwater remediation, block cave mining, rock burst mitigation, and water well development.
This paper characterizes a range of hydraulic fracturing applications in terms of the objectives, techniques, and potential for environmental concerns associated with the standard methods. A nomenclature that clearly differentiates discrete applications is presented that is intended to help prevent the lumping of all hydraulic fracturing techniques into a single basket.
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- Numerical Study of Interaction Between Hydraulic Fracture and Discrete Fracture Network
- A. Riahi ; B. Damjanac
- Book Title / Journal: Effective and Sustainable Hydraulic Fracturing - Chapter 13
- Year: 2013
- Rock Mechanics ; Mining
- Keywords: discrete fracture network ; DFN ; hydraulic fracturing ; rock mass
- Description
- This paper discusses the interaction between hydraulic fracturing and the pre-existing dis‐
crete fracture network (DFN) in a rock mass subject to in–situ stresses. Two–dimensional
computational model studies have been used in an initial attempt towards understanding how reservoir response to fluid injection is affected by some of the DFN characteristics and to operational variables such as injection rate.
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