Understanding the changes in the elastic and transport properties of organic-rich marl upon maturation is a key to developing rock physics models for reservoir characterization. We conducted confined pyrolysis of Eagle Ford marl cores and monitored the changes in the elastic and transport properties from immature to early-peak oil, late oil, and through to gas windows. The results systematically showed increasing porosity, decreasing velocity, and increasing permeability as maturation progressed, with most of the changes occurring in the late oil window. We also tracked a number of geochemical properties and found that the increased porosity was mainly secondary organic porosity resulting from the loss of kerogen volume. This leads to two possible mechanisms driving the changes. First, the shrinkage of kerogen volume forms low-aspect ratio pores around the kerogen body that greatly decrease velocity and increase permeability in the late oil window. Second, the loss of kerogen volume takes the form of nano-sized spongy pores inside the kerogen body that reduce the elastic moduli of kerogen and ultimately decrease the velocity of organic-rich marl upon maturation.

Presentation Date: Wednesday, October 17, 2018

Start Time: 8:30:00 AM

Location: 202A (Anaheim Convention Center)

Presentation Type: Oral

This content is only available via PDF.
You can access this article if you purchase or spend a download.