--> --> High-Resolution Sequence Stratigraphy of Fluvial Deposits of Potiguar Basin, Northeast Brazil: A Tool for Improving Hydrocarbon Production and Reserves

2018 AAPG International Conference and Exhibition

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High-Resolution Sequence Stratigraphy of Fluvial Deposits of Potiguar Basin, Northeast Brazil: A Tool for Improving Hydrocarbon Production and Reserves

Abstract

High-resolution sequence stratigraphy is an efficient method to define reservoir zonation of producer oil fields because it identifies the main heterogeneities responsible for vertical reservoir compartmentalization at the lowest scales of observation, generally below seismic resolution. Aiming to help reservoir management and to seek new opportunities in mature fields, this method was applied to the Cenomanian fluvial Açu Formation, the main oil bearing formation of the Potiguar Basin. Maximum Regressive Surfaces (MRS), Maximum Flooding Surfaces (MFS) and Subaerial Unconformities (SU) were interpreted based in rock, well, and production data. These surfaces were correlated throughout the study area and allowed the identification of eleven high-frequency depositional sequences. The main fluvial reservoirs are preserved in the transgressive systems tracts, and hence, bounded by MRS/SU (a superimposed surface) and MFS. Compared to the former four lithostratigraphic zones, the new chronostratigraphic framework allowed the mapping of intervals with high water cuts, which are harmful to oil production, and intervals with residual oil that were never opened to production. Furthermore, the high-resolution stratigraphic reservoir zonation allowed the construction of more detailed and predictive conceptual and 3D numerical geological models that is much more representative of the fluvial system and its heterogeneities, so that the resulting fluid flow simulations turned to be more realistic. This methodology represents a great opportunity to improve oil reserves and production in Potiguar Basin oil fields.