Geomechanical and geometric seismic attributes in an interpretation workflow for characterization of unconventional reservoirs

Abstract

Conventional seismic attributes often provide satisfactory results, especially in the characterization of conventional reservoirs such as sandstones. This is not so evident with more compact, low-permeability, and apparently uniform reservoirs, which comprise substantial reserves in amounts unthinkable a few decades ago, and whose development seemed almost impossible until very recently. Unconventional reservoirs considered in this article are located in a predominantly Jurassic-Cretaceous rifted depositional basin. The basin shifted into an early sag phase during the late Jurassic and early Cretaceous, resulting in the accumulation of a thick series of carbonates and shales. Tithonian, Berriasian and Valanginian rocks compose the segment of the geologic column under consideration. The studied sedimentary sequence is a highly prolific oil-prone source rock, with total organic carbon (TOC) up to 8 wt% and amorphous organic matter (type I/II kerogen) deposited in a euxinic paleoenvironment which generated sulfur-rich oils.