Large-Scale Physical Simulation Experiment Research for Hydraulic Fracturing in Shale

Abstract

Successful development of shale gas in North America triggered great enthusiasm of developing shale gas in China. Experiments for hydraulic fracturing shale Outcrops sample in 762ϫ762ϫ914mm(height) were performed by using large-scale true tri-axial testing system to study what kind of hydraulic fracture will be for South China marine shale and how the formation condition or the human-controllable parameter influence the fracture complexity. Investigations of fracture geometry and fracture complexity are conducted with different natural fracture distribution, different main stress difference, different fracturing fluid viscosity, different injection rate, using methods such as acoustic emission monitoring and cutting the rock sample into pieces. The testing results show the hydraulic fracturing in shale generates more complex fractures than that of in sandstone, where both tensile and shear cracks are observed. Natural fractures, shale bedding and small principal stress differences are in helping to form complex fractures. When a low viscosity fluid is used, complex fractures are easier achieved than that with high viscosity fluid. This work explores a way of conducting hydraulic fracturing large-scale shale test. The testing results provide important basis for numerical simulation of fracture propagation, pre-frac layer or stage choosing and fracturing design optimization for hydraulic fracturing in shale.

An Overview of Principles and Designs of Hydraulic Fracturing Experiments and an Inquiry into the Influence of Rock Permeability and Strength on Failure Mode

“…It is imperative that the fracturing fluids are mixed with tracers so as to easily mark the pattern of fractures. The tracer may be a fluorescent powder as used in the works of Wang et al [19], de Pater and Beugelsdijk [14] and Beugelsdijk et al [15]; or a dye, as applied by Zhao et al [11] and Murdoch [25].…”

“…The pressure or flow rate must be sufficient to initiate and propagate fractures and is usually supplied by a servo-controlled pumping system (e.g. [10,11,13,19,22,24]). Wang et al [19] There is no standardised fracturing flow rate or pressure.…”

“…[10,11,13,19,22,24]). Wang et al [19] There is no standardised fracturing flow rate or pressure. Certain key considerations determine the selection of injection flow regimes.…”

Numerical Analysis of Multiple Factors Affecting Hydraulic Fracturing in Heterogeneous Reservoirs Using a Coupled Hydraulic-Mechanical-Damage Model

“…Multiple secondary fractures, even tertiary fractures, generate on the main fractures and eventually form complex HFs. Whether tight glutenites can form complex HFs or not depends on geological factors and fracturing operational factors [22][23][24][25][26].…”

A Laboratory Study of the Effects of Interbeds on Hydraulic Fracture Propagation in Shale Formation

“…Van Eekelen et al [15] studied the hydraulic fracture propagation in layered formation and analyzed the fracture arresting effects. Recently, we have learned that in shale hydraulic fracturing, the natural fractures and shale bedding contributed to form complex fractures [16].…”