Top Down or Bottoms Up? Getting a Grip On Reservoirs When it
comes to evaluating hydrocarbon reservoirs and predicting
production performance, one thing is certain: Uncertainty. This
fact has long plagued geoscientists and engineers as they strive
to quantify myriad uncertainties in the complex subsurface
environs, such as porosity, permeability, structural surfaces
and more. “Evaluating uncertainty is becoming more and more
important,” said Jan Inge Tollefsrud, technical manager
responsible for uncertainty solutions at Roxar. “This is because
new discoveries are getting smaller even though the number of
discoveries is still high.” To begin at the beginning, it’s
imperative to understand the underlying factor that impacts your
ability to quantify what the uncertainty is. It’s not the
reservoir; it’s you. “Uncertainty is a function of your state of
knowledge and not an intrinsic quantity of the physical world,”
said Mike Christie, professor of reservoir simulation at Heriot-
Watt University in Edinburgh. “It’s