Study on rock mechanical properties of different lithologies in marine continental transitional formation:a case study of the Shanxi Formation in the eastern margin of Ordos Basin
Taking the Shanxi Formation in the eastern margin of the Ordos Basin as the research object,the mechanical tests such as single triaxial compression,tensile strength and fracture toughness were carried out,and then the mechanical properties of rocks with different lithology were studied.The results show that there are obvious differences in the mechanical properties of different lithologic rock samples in Shanxi Formation in the eastern margin of Ordos Basin.The compressive strength and elastic modulus of silty shale are high and Poisson's ratio is small.The peak strain of rocks in different lithology reservoirs is obviously different,and the deformation characteristics are quite different.The failure mode of rocks is mainly splitting failure under uniaxial compression,showing obvious brittle characteristics.With the increase of confining pressure,the failure mode changes from splitting failure to shear failure,the brittleness of rock decreases and the ductility increases.The fracture surface density and fractal dimension of silty shale are large under compression,which has the potential to form complex fracture network.The research results provide reference for subsequent wellbore trajectory optimization,fracturing construction and stimulation plan formulation.
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