  Geological process models simulate a range of dynamic processes to evolve a
base topography into a final 2D cross-section or 3D geological scenario. In
principle, process parameters may be updated to better align with observed
geophysical or geological data; however, many realisations of process models
that embody different conceptual models may provide similar consistency with
observed data, and finding all such realisations may be infeasible due to the
computational demands of the task. Alternatively, geophysical probabilistic
tomographic methods may be used to estimate the family of models of a target
subsurface structure that are consistent both with information obtained from
previous experiments and with new data (the Bayesian posterior distribution).
However, this family seldom embodies geologically reasonable images. We show
that the posterior distribution of tomographic images can be enhanced by
injecting geological prior information into Bayesian inference, and we can do
this near-instantaneously by trained MDNs. We invoke two geological concepts as
geological prior information: a braided river system, and a set of marine
parasequences, each parameterised by a GAN. Data from a target structure can
then be used to infer the image parameter values using either geological
concept using MDNs. Our MDN solutions closely resemble those found using
expensive McMC methods, and while the use of incorrect geological conceptual
models provides less accurate results the mean structures still approximate the
target. We then show that a classification network can infer the correct
geological conceptual model. Thus, imposing even incorrect geological prior
information may improve geophysical tomographic images compared to those
obtained without geological prior information, and in principle geological
conceptual models can be inferred directly from geophysical travel time data.

Geophysics