The mineral composition analysis and static and dynamic mechanical parameters synchronous test were used to analyze the experimental rock mechanics of the thick Paleogene gypsiferous mudrocks in the Yubei area in the southwest of the Tarim Basin. The results indicated that under uniaxial conditions,the gypsiferous mudrock showed obvious characteristic of elastic deformation,while under triaxial conditions,its elastic-plastic characteristics were obvious. Under formation confining pressure conditions,with the increase of axial load,the gypsiferous mudrock had experienced five stages such as initial compaction,linear elastic deformation,nonlinear stability extensional deformation,nonlinear unsteady extension deformation and macroscopic rupture. Compared to the gypsiferous mudrocks(GMR),argillaceous anhydrite rocks(AR)had higher VP,VS and VP/VS. There was a very good positive correlation between VP/VS and the anhydrite content. While the anhydrite content increased from about 10% to 90%,the VP/VS value increased from 1.63 to 1.88 and the increase amplitude was significant. And then the conversion relationship of time difference between longitudinal wave and transverse wave of gypsiferous mudrock samples were obtained precisely. The dynamic Young’s modulus,Poisson’s ratio and shear modulus of AR were obviously higher than that of GMR. The conversion relationships among dynamic and static mechanical parameters of the gypsiferous mudrocks were obtained finally.
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YIN Shuai, YAN Lingling, SONG Yuehai, CHENG Hanlie. Experimental analysis of rock static and dynamic mechanical properties of deep gypsiferous mudrock cap[J]. Petroleum Geology and Recovery Efficiency,2018,25(2):37~41