Uncertainty analysis in a deep-water turbidite reservoir in the Gulf of Mexico is discussed in this chapter. Six major factors were addressed in the study to capture uncertainty: reservoir compartmentalization; acoustic impedance (AI) attenuation caused by the salt overhang; AI attenuation caused by fluid effects; petrophysical properties; pressure, volume, and temperature; and aquifer strength uncertainty. We characterized and quantified the uncertainties in the reservoir by integrating information from various disciplines: geophysics, petrophysics, geology, and engineering. This uncertainty workflow enabled us to make sound business decisions in a timely manner.

A base case scenario model was first built integrating well and seismic data. Multiple realizations were then simulated by varying petrophysical parameters such as porosity, permeability, and saturation; turning on and off various potential barriers; and processing the impedance volume for different scenarios. The effect of the drive mechanism on ultimate recovery was also studied by running scenarios with varying amounts of aquifer size and strength. The outputs of various scenarios were compiled to generate a probability distribution curve of the expected reserves and production rates. The outputs were then incorporated into an economic model to evaluate the viability of the project.