SKRETTINGLAND, K., S. T. OPDAL, A. MAMRE, and A. HENRIQUEZ*, Statoil, Stavanger, Norway; and T. EGELAND, Norwegian Computing Center

ABSTRACT: Uncertainty in Production Profiles: Three Case Studies

A methodology for calculating the uncertainty in the production profiles due to the uncertainties in the geological model and other input parame parameters is applied to an oil, a giant gas, and a gas-condensate field.

The methodology consists of six steps: (1) establishment of the uncertainties in the input parameters, (2) setup of the reservoir simulation model for the different uncertainties, (3) running the simulation varying one parameter at a time, (4) use of experimental design techniques for choosing the parameter combinations for simulation runs where several parameters vary from their base values, (5) fitting the production profiles at different chosen times with an n-dimensional surface where the uncertain parameters

are considered as independent but possibly correlated, and (6) doing a Monte-Carlo simulation on the independent parameters with the given uncertainties to determine the uncertainty in the production profiles.

The methodology has been developed further to calculate the net present value of different field development alternatives, and it has been applied to one field case.

Guidelines based on the specific examples will be given for the first, second, and third steps. Different methods are compared for the fourth, fifth, and sixth steps, using commercially available programs, including analytical techniques.

With this methodology, investments and timing of oil and gas fields for fulfilling contracts can take into account all uncertainties in the geological, simulation, and production models.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.