Abstract
Subsurface characterization is important for the detection and
development of underground resources. Useful subsurface models can
correctly make production forecast and optimize development plans, such
as infill well location in an aquifer, geothermal, and hydrocarbon
reservoir development. A useful subsurface model should honor geological
concepts as well as all the available measurements, such as fluid
production history, geophysical measurements. However, common subsurface
modeling methods cannot efficiently honor the two concepts. To build
subsurface models in a way that it is easy to condition them to both
geological concepts and available measurements, we develop a new machine
learning method, referred to as the stochastic pix2pix method. In this
method, we use convolutional neural networks and adversarial neural
networks to stochastically generate new subsurface models matching both
geological concepts and static measurements, such as seismic and well
data. This method first extracts the depositional patterns from analog
training images, such as outcrops, high-resolution seismic images, and
depositional process-based reservoir models, and then minimizes the
Jensen-Shannon entropy between the training images and new subsurface
models, as well as the mismatch of static measurements. The hydraulic
inverse problem is solved with a machine learning-based proxy model on
the model parameter space defined by stochastic pix2pix. The stochastic
pix2pix method helps maintain the match of geological concepts and
static measurements during the inversion. To verify and benchmark our
procedure, we show the conditional subsurface models generated with
stochastic pix2pix reproduce the geological concepts as good as
synthetic unconditional process-based models. we successfully build
reservoir models for channel and turbidite fan systems, where the
depositional patterns of common geobodies are well reproduced. The
synthetic well data, seismic interpretation, net-to-gross ratio, and
time records of fluid production are well-matched with this new method.
Additionally, we generate conditional subsurface models 90% faster than
with conventional object-based modeling methods and with more accurate
reproductions of the available measurements.