Experimental investigation on elasticity of glutenite

Key words:  rock property  petrophysics  elastic moduli  Dongying northern zone  glutenite  Biot Gassmann theory  Biot 's coefficient  compressional wave and shear wave velocity prediction

Abstract:

The samples of rock were obtained from glutenite reservoir area of the Eastern Dongying north zone, Jiyang Depression. The elastic properties of rock were measured. First, the elastic moduli of rock matrix were calculated using effective medium theory. Through rock thin section analysis and elastic moduli test, the variation characteristics about Biot 's coefficient of glutenite were studied. The relationship between dry rock Biot 's coefficient and φ/φc(φ and φ_c are rock porosity and critical porosity respectively) were established by the way of nonlinear regression according to different lithologies. The elastic moduli and wave velocities of rock saturated by fluid were calculated by the extended Biot Gassmann model. The predicted compressional and shear wave velocities were compared with those velocities measured in laboratory. The Biot Gassmann theory can be applied to analyze the elastic characteristics of glutenite.The results show that the elastic moduli of core matrix calculated by HS boundary model are more accurate than empirical value and reduce the effect of saturated fluid on the elastic moduli. Biot 's coefficient describes the stiffness of the rock pores and relates to the lithology, mineral composition, and internal structure. It increases with porosity increasing and decreases with effective pressure increasing. The compressional wave and shear wave velocities predicted by the extended Biot Gassmann theory agree well with the velocities measured in laboratory. The process of prediction is also simplified.