Doctor of Philosophy (PhD)
The scarce amount of conventional hydrocarbon reservoirs and increase of fuel consumption in the world have made production from unconventional hydrocarbon resources inevitable. Because of the low permeability of unconventional formations, fractures are the main paths for the fluid to flow. Therefore, detailed knowledge of the size, orientation, and permeability of the fracture systems are essential for reservoir engineers. Permeability of the fractures is function of their volume and opening, and stress and fluid pore pressure distribution in the formation. Since reservoir pressure may change over the production life of the reservoir, studying stress redistribution and mechanical behavior of the reservoirs due to the fluid pressure alteration plays a critical role in successfully operating the hydrocarbon fields. This research investigates the behavior of poroelastic inclusions or inhomogeneities due to the pore pressure change, with applications in reservoir geomechanics. Considering different material properties and different pressure/temperature of hydrocarbon bearing formations in comparison to those of the surrounding geological structures, hydrocarbon reservoirs and subsurface fractures can be considered as inhomogeneities embedded inside an infinite poroelastic medium. Moreover, elliptic fractures are special cases of ellipsoidal inhomogeneities when their elastic moduli are zero, and one of the principal axes of the ellipsoid approaches zero. This dissertation is concerned with these two topics: the thorough study of poroelastic inclusions and their applications in reservoir geomechanics; and poroelastic fractures and their implications on the performance of hydrocarbon reservoirs. Analytical solutions for applied stress and strain distribution around single and double inhomogeneous poroelastic inclusions due to pore pressure changes in inclusions are derived, using Eshelby Equivalent Method (EIM) and assuming no hydraulic communication between the inclusion and the surrounding medium. This assumption is reasonable for modeling situations with large discrepancy between the permeability of the inclusion and the matrix. Later, considering hydraulic communication between the inclusion and the matrix, solution for the volume change of ellipsoidal poroelastic inclusions are derived.
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Bedayat, Houman, "Poroelastic Inhomogeneities: Applications in Reservoir Geomechanics" (2014). LSU Doctoral Dissertations. 1803.
Dahi Taleghani, Arash