Paulo S. da Cruz¹, Roland N. Horne², Clayton V. Deutsch³
(1) Petrobras and Stanford University, Stanford, CA
(2) Stanford University, Stanford, CA
(3) University of Alberta, Edmonton, AB

Abstract: The quality map - a tool for reservoir uncertainty quantification and decision making

The parameters that govern fluid flow through heterogeneous reservoirs are numerous and uncertainty. Even when it is possible to visualize all the parameters together, it is difficult to predict the dynamic reservoir responses to production. A flow simulator may be used to evaluate the responses, but normally only one deterministic set of parameters is considered and no uncertainty is associated with the responses or taken into account for the decisions. This paper introduces the concept of a "quality map", which is a two-dimensional representation of the reservoir responses and their uncertainties. The quality concept may be applied to compare reservoirs, to rank stochastic realizations and to incorporate reservoir characterization uncertainty into decision making, such as choosing well locations. The data points necessary to generate the quality map are obtained by running a flow simulator with a single well and varying the location of the well in each run to have a good coverage of the entire horizontal grid. The "quality" for each cell is the cumulative oil production of the well producing in that cell. The geological model uncertainty is captured by multiple stochastic realizations. One quality map is generated for each realization and the difference between the realization maps is a measure of the uncertainty in the flow responses. For each cell, the lower quartile of the local distribution of quality is extracted to build a map, which can be used for decision making.

The methodology is presented in detail and the applications are demonstrated with fifty realistic reservoir models.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana