K. Cliffe, D. Holton, P. Houston, C. Jackson, S. Joyce & A. Milne
Int. J. Numer. Anal. Mod., 8 (2011), pp. 543-565
Many geological formations consist of crystalline rock that have
very low matrix permeability but allow flow through an interconnected network
of fractures. Understanding the flow of groundwater through such rocks
is important in considering disposal of radioactive waste in underground repositories.
A specific area of interest is the conditioning of fracture transmissivities
on measured values of pressure in these formations. While there are existing
methods to condition transmissivity fields on transmissivity, pressure and
flow measurements for a continuous porous medium, considerably less work has
been devoted to conditioning discrete fracture networks. This article presents
two new methods for conditioning fracture transmissivities on measured pressures
in a discrete fracture network. The first approach adopts a linear approximation
when fracture transmissivities are mildly heterogeneous, while the
minimisation of a suitable objective function is undertaken when fracture transmissivities
are highly heterogeneous. The second conditioning algorithm is a
Bayesian method that finds a maximum a posteriori (MAP) estimator which
maximises the posterior distribution defined by Bayes