### A Finite-Element Procedure to Determine Biots Coefficients of Anisotropic Poroelasticity

#### Abstract

Numerical rock physics offers an alternative approach to laboratory measurements, being repeatable and essentially free from experimental errors. In this work, we present a set of oscillatory numerical experiments to determine the coefficients of the stress-strain relations of a poroelastic medium saturated by a single fluid. The experiments represent a set of low-frequency (quasi-static) compressibility tests applied to a representative sample of bulk material, where the fluid has enough time to reach pressure equilibration. Each test is associated with a boundary-value problem formulated in the spacefrequency domain and solved with a finite-element procedure. The methodology is used to estimate the poroelasticity coefficients of a homogeneous sample of isotropic Utsira sandstone saturated with either brine or CO2, and the eight coefficients corresponding to a periodic sequence of thin isotropic layers of brine-saturated mudstone and CO2-saturated sandstone. This medium is transversely isotropic in the long-wavelength limit.

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Güemes 3450

S3000GLN Santa Fe, Argentina

Phone: 54-342-4511594 / 4511595 Int. 1006

Fax: 54-342-4511169

E-mail: amca(at)santafe-conicet.gov.ar

**Asociación Argentina de Mecánica Computacional**Güemes 3450

S3000GLN Santa Fe, Argentina

Phone: 54-342-4511594 / 4511595 Int. 1006

Fax: 54-342-4511169

E-mail: amca(at)santafe-conicet.gov.ar

**ISSN 2591-3522**