Stochastic simulation of cave systems with ODSim
in: Proc. 28th Gocad Meeting, Nancy
Abstract
Cave systems are a challenge in both groundwater and petroleum modelling as their high spatial
heterogeneity considerably in
uences
ow in many carbonate reservoirs. The complexity of the
dissolution process involved in karst development make the building of accurate 3D description of
karst networks geometries dicult. For this reason, Henrion et al. [2007] develop an alternative
approach based on stochastic methods to generate 3D realistic cave systems. In the continuation,
this paper focus on the extraction of channel
ow network and the condidtioning of karst realizations
to
eld data and secondary informations such as water level. The
rst step of the method consists
in building the structural model which includes a network of discontinuities such as fractures and
bedding planes. The second step reproduces the selective nature of karst processes (enlarging
the fractures presenting the most favourable conditions for dissolution): the structural model is
discretized into a graph of connectivities [Vitel, 2007] allowing the use of a graph search algorithm
to
nd least-cost paths (preferential
ow paths) between given initial nodes (sinks) and goal nodes
(sources). In Henrion et al. [2007], fractures connected to extracted path were the skeleton of further
karst development occurring on the whole fracture. Here, to be more consistent with chenalized
ow encountered on fracture and bedding planes, karst is directly simulated around the extracted
ow paths ("dissolution paths"). At this step data conditioning may be introduced. Eventually,
to simulate the extension of conduits around "dissolution paths", the 3D distance to these paths
which can be seen as a map of the potential of karstication is computed. A distance cuto
is then
generated by sequential Gaussian simulation and is used to perturb the initial distance function,
creating realistic karst geometry. Data conditioning may also be included at this last step.
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BibTeX Reference
@inproceedings{223_pellerin, abstract = { Cave systems are a challenge in both groundwater and petroleum modelling as their high spatial heterogeneity considerably in uences ow in many carbonate reservoirs. The complexity of the dissolution process involved in karst development make the building of accurate 3D description of karst networks geometries dicult. For this reason, Henrion et al. [2007] develop an alternative approach based on stochastic methods to generate 3D realistic cave systems. In the continuation, this paper focus on the extraction of channel ow network and the condidtioning of karst realizations to eld data and secondary informations such as water level. The rst step of the method consists in building the structural model which includes a network of discontinuities such as fractures and bedding planes. The second step reproduces the selective nature of karst processes (enlarging the fractures presenting the most favourable conditions for dissolution): the structural model is discretized into a graph of connectivities [Vitel, 2007] allowing the use of a graph search algorithm to nd least-cost paths (preferential ow paths) between given initial nodes (sinks) and goal nodes (sources). In Henrion et al. [2007], fractures connected to extracted path were the skeleton of further karst development occurring on the whole fracture. Here, to be more consistent with chenalized ow encountered on fracture and bedding planes, karst is directly simulated around the extracted ow paths ("dissolution paths"). At this step data conditioning may be introduced. Eventually, to simulate the extension of conduits around "dissolution paths", the 3D distance to these paths which can be seen as a map of the potential of karstication is computed. A distance cuto is then generated by sequential Gaussian simulation and is used to perturb the initial distance function, creating realistic karst geometry. Data conditioning may also be included at this last step. }, author = { Pellerin, Jeanne AND Henrion, Vincent AND Caumon, Guillaume }, booktitle = { Proc. 28th Gocad Meeting, Nancy }, title = { Stochastic simulation of cave systems with ODSim }, year = { 2008 } }