(1. State Key Laboratory of Petroleum Resources and Prospecting，China University of Petroleum，Beijing 102249，China；
2. CNOOC Research Institute，Beijing 100027，China)
Abstract：Fracture toughness of rock is one of the most important factors for evaluating the fracability of shale reservoir quantitatively. Based on straight seam grooving Brazilian disc test(SNBD)，fourteen shale pieces taken from Longmaxi Formation have been tested to measure fracture toughness of both type I and II. And by using the above results，combining with the logging data where the cores locate，the paper makes a regression of the shale fracture toughness with the data of density，acoustic time and GR logging. Comparing previous prediction model based on tensile strength，a direct relationship between fracture toughness and geophysical logging data was established in this paper. According to the prediction model，fracture toughness of organic-rich shale is proportional to the density and interval transit time of rock，while inversely proportional to its shale content. The more total organic carbon(TOC) or clay mineral is， the smaller fracture toughness is，it is more easily to extend forward after crack initiation. The results indicate that the fracture toughness of predication model has a pretty good correlation with that measured by SNBD. This paper can provide important theoretical basis for engineering design process to identify“Sweet Spots”.
陈建国1，邓金根1，袁俊亮2，闫 伟1，蔚宝华1，谭 强1. 页岩储层I型和II型断裂韧性评价方法研究[J]. 岩石力学与工程学报, 2015, 34(06): 1101-1105.
CHEN Jianguo1，DENG Jingen1，YUAN Junliang2，YAN Wei1，YU Baohua1，TAN Qiang1. RESEARCH ON THE DETERMINATION OF TYPE I AND II OF SHALE FORMATION FRACTURE TOUGHNESS. , 2015, 34(06): 1101-1105.
GOLSHANI A，OKUI Y，ODA M，et al. A micromechanical model for brittle failure of rock and its relation to crack growth observed in triaxial compression tests of granite[J]. Mechanics of Materials，2006，38(4)：287-303.
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2015, Vol. 34 
