| dc.description.abstract | Poroelasticity is fundamental in the application of petroleum reservoir mechanics and production, wellbore stability, and hydraulic fracturing. Biot’s coefficient is key mechanical quantity for better understanding of the poroelastic behavior of the reservoir matrix under stress. Its measurement in the laboratory traditionally involves a mechanical setup, such as tri-axial compression test, and is time-consuming and costly. However, during the porosity and permeability measurements under stress, Biot’s coefficient is often assumed equal to one due to inherent difficulties in its measurement. In this study, a new analytical method is presented for estimating Biot’s coefficient of the rock samples in the laboratory during porosity measurement under stress. The approach can be extended to permeability measurements later. The technique used in this study requires helium uptake by the sample under predetermined confining pressure and pore pressure, and the application of Boyle’s law. It allows simultaneous prediction of the sample pore volume, the coefficient of isothermal pore compressibility, and the effective stress coefficient. The effective stress coefficient is a precursor of the Biot’s coefficient and influenced by the applied confining and pore pressure values. In this thesis we show a new graphical approach to predict the Biot’s coefficient from these laboratory quantities. The procedure is fast and can be performed in any reservoir petrophysics laboratory using the traditional Hassler core holder setup. Biot’s coefficient estimated for sandstone, carbonate, and shale samples are in a range between 0.46 and 1, which is commonly found in the literature performing the mechanical tests. The proposed method allows the determination of Biot’s coefficient using the conventional porosimeter set up without the need for sophisticated geomecanical tests. | en |
