Source Rocks from Seismic (SRfS) Part I - Fundamentals

Our ability to identify a source rock in the subsurface and quantify its parameters has a significant impact on prospect risking and petroleum play analyses. The purpose of this paper is to demonstrate why conventional seismic data can be used to risk source rock presence in petroleum system analyses. We use rock physics relationships from well logs, which are constrained by core data measurements. Established relationships between organic content and acoustic properties are used to model the expected seismic responses at the top and base of source rock intervals. Rock property analyses and forward seismic modeling of organic-rich shales demonstrate that they have characteristic acoustic properties that allow for robust seismic interpretation. Our models suggest that source rock shale intervals can be identified and characterized on conventionally processed seismic data if their total organic carbon (TOC) content is larger than 3-4 wt.% and their thickness is more than 15-20 m. This paper is the first of two companion papers on Source Rock from Seismic (SRfS). Here, we discuss the fundamentals of SRfS; in the companion paper (Gading et al., 2012) we present applications of our SRfS methodology.