2022-05-24T03:04:38Zhttps://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/221932016-02-16T07:02:15Zcom_10261_87com_10261_8col_10261_466
A hybrid technique to compute the pore pressure changes due to time varying loads: application to the impouding of the Itoiz reservoir, Northern Spain
Luzón, Francisco
García-Jerez, Antonio
Santoyo, Miguel Ángel
Sánchez-Sesma, Francisco José
Poro mechanics
Itoiz
In the low frequency limit of the Biot equations the variations of the pore pressure in a fluid
saturated elastic medium can be approximately described by a Homogeneous Diffusion
Equation (HDE). It can be used, for example, to reconstruct the tensor of hydraulic diffusivity
when connecting the microseismicity associated with fluid injection in boreholes, and
assuming that these injections cause perturbations of the pore pressure in the rock. In
poroelasticity this can be considered as an uncoupled problem. That is, elastic stresses and
pore pressure are independent of each other in the governing partial differential equations of
the problem. On the other side, those phenomena in which it is necessary to take into account
the systematic influence of elastic stresses and pore pressure on each other are known as
coupled problems. The intermediate problem, in which pore pressure does not influence the
elastic stresses whereas the stresses influence the pressure, is known as the decoupled one.
This approximation leads to an Inhomogeneous Diffusion Equation (IDE) that is being
commonly used to analyse the pore pressure variations next to dams due to time varying
water loads in their reservoirs. When considering flow boundary conditions, the solution of
this equation can be obtained as the superposition of a term computed from the HDE with the
Dirichlet boundary condition (the term due to the pore pressure diffusion), and the solution of
an initial value problem in which the inhomogeneous term related with the stress variations in
the IDE is considered (the solution due to the compression in the media). In this work we use
a hybrid technique to estimate the pore pressure changes in this decoupled problem in which
two different techniques are joined to calculate each one of the partial solutions. This hybrid
technique has been used to estimate the pore pressure variations produced by the impounding
of the Itoiz reservoir, northern Spain. The filling of this reservoir began in January 2004 and
every hydrological year received water reaching in 2008 its maximum capacity with
approxitlrately 90 m of water column at the dam. We give special attention to the pore
pressure variations at the hypocenter locations of the main earthquakes of the series occurred
on September 2004 next to Itoiz reservoir, with magnitudes M≤4.6.
2010-03-10T11:04:15Z
2010-03-10T11:04:15Z
2009
comunicación de congreso
Poromechanics IV : fourth Biot Conference on Poromechanics, Columbia University, New York, June 8-10, 2009. p. 1109-1114
978-1-60595-006-8
http://hdl.handle.net/10261/22193
eng
openAccess
DEStech Publications