An inverse technique for developing models for fluid flow in fracture systems using simulated annealing

Abstract

One of the characteristics of flow and transport in fractured rock is that the flow may be largely confined to a poorly connected network of fractures. In order to represent this condition, Lawrence Berkeley Laboratory has been developing a new type of fracture hydrology model called an “equivalent discontinuum” model. In this model we represent the discontinuous nature of the problem through flow on a partially filled lattice. This is done through a statistical inverse technique called “simulated annealing.” The fracture network model is “annealed” by continually modifying a base model, or “template,” so that with each modification, the model behaves more and more like the observed system. This template is constructed using geological and geophysical data to identify the regions that possibly conduct fluid and the probable orientations of channels that conduct fluid. In order to see how the simulated annealing algorithm works, we have developed a synthetic case. In this case, the geometry of the fracture network is completely known, so that the results of annealing to steady state data can be evaluated absolutely. We also analyze field data from the Migration Experiment at the Grimsel Rock Laboratory in Switzerland.

Estimation of reservoir properties using transient pressure data: An asymptotic approach

“…ods attempt to estimate parameters using stochastic optimization methods such as simulated annealing [Mauldon et al, 1993] or hybrid schemes such as simplex annealing [Pan and Wu, 1998]. More commonly, a linearized inversion technique is used iteratively to estimate parameter values.…”

Simulated annealing technique in discrete fracture network inversion: optimizing the optimization

“…Several authors have used SA to model reservoir fractures with certain success [3,4,7,10,13,15,20]. They attempt to evaluate spatial distribution of fracture intensity (or similar indexes that define fracture presence).…”

Enhancing gradient-based parameter estimation with an evolutionary approach

“…Mauldon et al (1993) developed models for fluid flow in fracture systems using simulated annealing. They designed a model template to identify regions of fluid conduction and fracture orientation when given the appropriate geological and geophysical data.…”