Rock quality assessment for hydraulic fracturing

The concept of brittleness as defined by a rock's ability to fail and maintain a fracture in a hydraulic fracture experiment plays a crucial role in the development of tight oil and gas. As such, various methodologies have been proposed in an attempt to quantify the degree of brittleness associated with a rock mass. These conventional methods have a few shortcomings. For example, failure criteria are not used and only the effective moduli are considered, leading to an incomplete description of the problem. In this paper, we address some of these issues by including failure criteria and rock physics models in the brittleness definition.