REALISTIC, STOCHASTIC, GEOLOGIC MODELING CAPABILITIES

                                                                                                                                                                                                                                                                                                                  Aquifer heterogeneity, and therefore flow and transport, is primarily controlled by the spatial distribution and connectivity of hydrofacies. A typical best practices model construction workflow first models the facies as geologic objects with realistic connectivity and then populates the discretization of each facies with its corresponding specific porosity and permeability distributions (facies parameters).  This model construction is currently constrained by the limitations of the one- and two-dimensional tools based on 2-point statistics (variogram).

Variogram-based simulation techniques such as transitional probability (TPRoGS) allow construction of facies models conditioned to borehole geologic and geophysical data, but the simulated depositional elements often do not look geologically realistic.  As an example, the statistical correlation of two points is not sufficient to model curvilinear or long-range continuous facies bodies such as sand channels.

Multiple-point statistics (MPS) combines the ability to simulate the shapes of geologic objects with the speed and ease of data-conditioning provided by the variogram-based techniques.  A two- or three-dimensional training image is used to infer higher order, MPS.  MPS extracts patterns characterized by MPS moments from the training image and anchors these patterns to the borehole data.

In areas of sparse data, a geologist's interpretation of borehole data and depositional setting may be required to control the spatial distribution of the simulated facies between the boreholes.  Facies depositional modeling (FDM) allows the modeler to quantify such information into a facies probability cube that can be spatially variable in order to constrain the MPS model.

The images compare simulations of similar channel network geologies: the first image, using a MPS simulation of a channel network, matches the relative proportions and simulates the connectivity of the geologic objects.  The second image, using a TPRoGS realization (plan view), matches the relative proportions of facies as well as the local 2-point transitional probabilities, but does not simulate well the connectivity of the geologic objects.

List of acronyms

FDM  Facies depositional modeling

MPS  Multiple-point statistics

TPRoGS  Transitional probability

Multiple-point stochastic simulation of a channel network

Transitional probability (TPRoGS) 2-point stochastic simulation of a channel network.