Chapter 14

Martha Cather
William Weiss
New Mexico Petroleum Recovery Research Center
Socorro, New Mexico, U.S.A.

The characterization of old fields lacking sufficient core and log data is a challenging task. This paper describes a methodology that uses both new and conventional tools to build a reliable reservoir model for the Sulimar Queen field. At the fine scale, permeability measured on a fine grid with a minipermeameter was used in conjunction with the petrographic data collected on multiple thin sections. The use of regression analysis and a newly developed fuzzy logic algorithm led to the identification of key petrographic elements that control permeability. At the log scale, old gamma ray logs were first rescaled/calibrated throughout the entire field for consistency and reliability using only four modern logs. Using data from one cored well and the rescaled gamma ray logs, correlations among core porosity, permeability, total water content, and gamma ray were developed to complete the small-scale characterization. At the reservoir scale, outcrop data and the rescaled gamma logs were used to define the reservoir structure over an area of 10 mi² (26 km²) where only 36 wells were available. Given the structure, the rescaled gamma ray logs were used to build the reservoir volume by identifying the flow units and their continuity. Finally, history-matching results constrained to the primary production