From Seismic Space to Pore Space: Models That Support the Exploration in the Pre-Salt Play of Santos Basin, SE Brazil

Abstract

The 2006 discovery of carbonate reservoirs in the pre-salt play of Southern Brazil unlocked an exciting opportunity for the oil industry. As more data has become publicly available, integrated multi-scale approaches have become part of the process to understand such complex a play. The objective of this study is to go through the different approaches of the pre-salt reservoir interpretation through the lens of a company with limited access to data.

An integration of scarce data and information available from the discoveries and fields in Santos Basin was performed to build the foundation of our volumetric evaluation and risk assessment for undrilled areas. At the regional scale, the Aptian pre-salt carbonates were categorized into two broad groups: the predominantly hydrothermally influenced carbonates (where most of the carbonates were abiotically precipitated) and the predominantly microbial carbonates (where most of the carbonates were biotically precipitated). Each one of these “end members” have distinctive seismic geometries that are the large-scale expressions of reservoirs developed within a specific paleogeographic context and a local tectonic setting that ultimately drives the predominant chemical precipitation process.

A detailed petrophysical analysis of greater than 60 wells that were drilled in the Santos Basin was used to characterize the different depositional types as well as to support future evaluations. Observations showed that, even at pore scales, a complex interaction of biotic and abiotic processes of carbonate deposition likely occurred, which suggests that one process seems to predominate over the other. Reservoirs, by consequence, show different pore architectures and different levels of continuity and connectivity in nearly every case. These conclusions are further supported by dynamic data that illustrate a different reservoir performance related to the specific depositional context.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018