Tensile and Shear Mechanical Characteristics of Longmaxi Shale Laminae Dependent on the Mineral Composition and Morphology

Energies

Ming Wang¹  Xiao Li¹  Xiaolin Huang¹  Lihui Li¹  Beixiu Huang¹ 

[1] Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;

关键词: shale laminae;    tensile strength;    shear strength characteristics;    fracture morphology;    Longmaxi Shale (China);   

DOI  :  10.3390/en13112977

来源: DOAJ

【 摘 要 】

Laminae are well developed in shale and generally influence fracture propagation during hydraulic fracturing. Hence, comprehensively understanding the tension and shear behaviors of shale laminae is crucial. There have been limited systematic studies thus far on the tensile and shear strength as well as fracture morphology of shale laminae. In this study, the Lower Silurian Longmaxi Shale (China) was investigated via Brazilian tensile and angle-varied plate shear tests. Five lamina types were tested, i.e., calcite (Cal), pyrite (Py), organic-enriched (Oc), the interface between Cal and Oc (Cal-Oc), and the interface between Py and Oc (Py-Oc) laminae. Results showed that the tensile strength was in the range 0.43–8.22 MPa, mainly in the order of Cal > Py > Cal-Oc > Py-Oc > Oc. The modes of fracture morphology were highly related to the occurrence, continuity, and mineralogy fillings of laminae. Shear strength parameters were within the range 22.50–29.64 MPa for cohesion and 37.29–43.60° for internal friction angle. Fracture surface roughness was strongly related to its cohesion. Calcite laminae considerably influenced the tensile fracturing of shale, suggesting that the geometry and properties of calcite lamina should receive more attention during the design of shale gas exploration.

【 授权许可】

Unknown