Abstract:Given the development of shale bedding in Tonghua, Northeast China, tri-axial compression experiments and P & S wave velocity (vP and vS) tests in two directions are carried out to analyze the variation of elastic modulus, Poisson's ratio, vP, and vS of shale in different directions. Relevant experiment data show that the shale anisotropy parameters ε and γ are linearly correlated under different confining pressure and the empirical formula built by linear regression can provide references for their prediction or testing. The anisotropy of favorable reservoir samples is much higher than that of unfavorable ones. As the confining pressure gets higher, both vP and vS increase and ε and γ become smaller. The vP/vS of shale is positively correlated to density and therefore negatively to total organic carbon (TOC). The vP/vS of favorable re-servoirs with high TOC is much lower than 1. 7, while the ratio of unfavorable reservoirs with low TOC is higher than this value, which can be taken as a marker to distinguish unfavorable reservoirs. With the increase in porosity, the elastic modulus of shale parallel to the bedding direction rises but declines vertical to the bedding direction. Our fin-dings can lay a foundation for the seismic quantitative prediction of shale brittleness and sweet spots.
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