The important participation of Colombian heavy oil fields at the country oil production and the current thermal recovery operations implemented for their exploitation have brought about the need of a proper characterization and understanding of the reservoir mechanical and petrophysical properties under different pressure and temperature conditions. According to this current demand, the present study aims to analyze and assess a set of 19 triaxial tests focusing on the behavior of petrophysical properties (porosity and permeability) in representative reconstituted samples of an uncemented formation. Among these triaxial tests, different condition of temperature, confining pressure, drainage, and loading conditions (DTXC, UTXC and DRTXC) are carried out in order to replicate the conditions occurring to the formation during thermal recovery processes and estimate the effects of these variations on sample’s properties. The analysis shows a direct dependence between the petrophysical properties and the confining pressure. In tests carried out under high confinement (effectives stress greater than or equal to 4 MPa) the porosity decreases during shear stage, whilst under low confinement (effective stress of 0.4 MPa) porosity increases during shear stage. On the other hand, the permeability decreases before and after the shear stage in tests with high confinement, whilst at low confinement values, permeability increases. Lastly, an especial case of stress path for the undrained triaxial tests is presented which shows an asymptotic behavior in the stress path describing the Mohr Coulomb failure envelope. This especial case of stress path could be useful to evaluate Mohr Coulomb failure envelope using a single sample.


Hydrocarbon reservoirs are subjected to different stress path during its productive life. Depending on the production/injection processes the rock can be subjected to a stress state where the horizontal stresses reduce (production) or increase (injection) (Morales-Monsalve et al., 2018). Besides, according to the redistribution of stress and pressure around the wellbore, the vertical stress might change (Ikogoll et al., 1989).

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