中南大学学报（自然科学版）Issue(2)：577-585,9.DOI:10.11817/j.issn.1672-7207.2016.02.030
基于能量耗散的页岩脆性特征
Shale brittleness estimation based on energy dissipation
摘要
Abstract
Given the brittleness criteria, which is defined by the brittle minerals contents, can not reflect the variation of brittleness at different mechanical conditions, brittleness estimation indices were proposed by the energy release and energy dissipation based on the complete stress- strain curves in uniaxial and triaxial compression tests. These proposed brittleness indices can comprehensively represent the mechanical properties of pre-peak and post-peak parts of shale. The brittleness at different confining pressure was evaluated using these brittleness indices. The results show that the proposed brittleness indices can simultaneously reflect the difficulty of brittle failure and the scale of brittleness. They can also be used to further analyses the failure mechanism of brittle rock and evaluate rock brittleness at different confining pressures. The shale brittleness is higher because the fracture index is larger and the brittleness index is smaller, when the post-peak rupture energy is smaller and the surplus energy is larger. But the brittleness is lower when the condition is opposed. These indices can be used to evaluate rock brittleness as they characterize the brittleness variation from different perspectives. With the increase of confining pressure within a certain range, the brittleness of shale decreases, and the incomplete failure can be easily observed as the number of broken rocks reduces gradually. It is indicated that the failure mechanism in turn is tensile failure, tensile-shear failure and shear failure. The failure mechanisms show the tendency that transforms from brittle at low confining pressure to ductile at high confining pressure. The results can provide technical reference for shale gas reservoir evaluation and for selection of high quality shale formations.关键词
页岩/脆性/能量耗散/应力-应变曲线/评价/破坏形态Key words
shale/brittleness/energy dissipation/stress-strain curve/evaluation/failure modes分类
建筑与水利引用本文复制引用
衡帅,杨春和,李芷,王磊,侯振坤..基于能量耗散的页岩脆性特征[J].中南大学学报（自然科学版）,2016,(2):577-585,9.基金项目
国家自然科学基金资助项目(51104144)；国家重点基础研究发展计划(“973”计划)项目(2010CB226701)；中石化科技部项目(P11015)(Projects (51104144) supported by the National Natural Science Foundation of China （51104144）
Project (2013CB228000) supported by the Major State Basis Research Development Program (973 Program) of China （2013CB228000）
Projects (P11015) supported by the Ministry of Science and Technology of Sinopec) （P11015）
