About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

DOI: 10.1306/0828171614717055

Organic geochemistry of the Eagle Ford Group in Texas

Andrea A. Miceli Romero,1 Thanh Nguyen,2 and R. Paul Philp3

1Chevron Basin Modeling Center of Research Excellence, Texas A&M University, College Station, Texas; [email protected]
2Department of Biomedical Engineering, National University of Singapore, Singapore; [email protected]
3ConocoPhillips School of Geology and Geophysics, University of Oklahoma, Norman, Oklahoma 73019; [email protected]

ABSTRACT

A comprehensive regional organic geochemical study was performed on outcrop and core samples from the Eagle Ford Group with the aim of determining variations in organic matter source, thermal maturity, and depositional environments. Total organic carbon (TOC) and Rock-Eval pyrolysis parameters show that the Eagle Ford Group has excellent hydrocarbon source rock potential and is dominated by type II kerogen. Distributions of regular steranes, hopanes, and monoaromatic steroids confirm a marine carbonate depositional environment. Aryl isoprenoid ratios suggest the occurrence of intermittent photic zone anoxia. The n-alkane and sterane distributions and the presence of pregnanes, homopregnanes, and gammacerane suggest deposition under hypersaline conditions particularly in west and east Texas. In east Texas, biomarkers indicate that the Eagle Ford Group was partially sourced from terrigenous organic matter and deposited under oxic–suboxic conditions. Thermal maturity parameters including the temperature at which the peak corresponding to the compounds produced from the thermal degradation of kerogen in the Rock-Eval chromatogram maximizes (Tmax), vitrinite reflectance, and biomarker ratios indicate that in west and central Texas, the Eagle Ford Group is immature to marginally mature; in southwest Texas it is in the oil to dry gas window; and in east Texas, the Eagle Ford is in the main stage of oil generation. Geochemical logs of biomarker ratios show that the Lower Eagle Ford Formation has the highest TOC and hydrogen index, particularly in the Lozier Canyon Member; experienced stronger anoxic conditions during deposition; and has lower clay content compared with the Upper Eagle Ford Formation. Geochemical parameters show that the latter may have received an additional siliciclastic and terrigenous organic matter input under oxic–dysoxic conditions. Isotope data indicate a marine organic matter source for the Eagle Ford Group, but surprisingly, δ13C values do not show significant organic facies, depositional environment, or thermal maturity variations.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].