This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 146658, ’The Effects of Fracturing Fluids on Shale Rock-Mechanical Properties and Proppant Embedment,’ by Ola Akrad, SPE, Jennifer Miskimins, SPE, and Manika Prasad, SPE, Colorado School of Mines, prepared for the 2011 SPE Annual Technical Conference and Exhibition, Denver, 30 October-2 November. The paper has not been peer reviewed. Development of shale reservoirs has grown significantly during the past few decades, driven by evolving technologies in horizontal drilling and hydraulic fracturing. The productivity of shale reservoirs depends highly on the design of the hydraulic-fracturing treatment. To design a successful treatment, a good understanding of the shale mechanical properties is necessary. The results of this study show that the greatest reduction of Young’s modulus occurs at high temperature and in samples with high carbonate content. Introduction In geology, shale traditionally has been defined as a sedimentary rock containing a high percentage (>50%) of clay and lower percentages of silica or carbonate minerals. However, many current shale prospects are not shales as defined in geology. Instead, they are “prospective-shale” reservoirs: fine-grained clastics characterized by ultralow permeability and usually composed of silica and carbonate minerals with a small amount of clay. Success in these shale systems depends largely on excellent hydraulic-fracturing designs that require a good understanding of the mechanical properties of the subject and confining formations. In hydraulic-fracturing design, Young’s modulus is a criterion used to determine the most-appropriate fracturing fluid and other design considerations. Young’s modulus provides an indication of the fracture conductivity that can be expected under the width and embedment considerations. Without adequate fracture conductivity, production from the hydraulic fracture will be minimal, or nonexistent. This study of Young’s modulus shows a significant decrease in the presence of certain fluids. Such decreases in Young’s modulus lead directly to decreases in fracture conductivity and, therefore, should be taken into account when designing the treatment to obtain a required fracture conductivity in a given reservoir. Methods and Testing Procedures It is known that fracturing fluids can affect the formation face of the created factures and cause damage. This damage can manifest itself as filter cake, fluid imbibition, and other damage mechanisms. A possible additional damage mechanism in prospective-shale systems is the potential weakening of the rock frame or modification of Young’s modulus, which could allow additional proppant embedment to take place. Such embedment, if occurring, could affect the fracture conductivity of a given treatment adversely.