Summary
Author(s):
Craig Schiefelbein (presenter), James Brooks, David Stansbury, Zvi Sofer, Adolpho Requejo, Geochemical Solutions International, Inc.
An integrated geochemical study of Petroleum Systems active in the Southeast Caribbean area has been conducted. The study is based on the analysis of >400 crude oils and condensates from major fields in order to evaluate: (1) source facies, (2) thermal maturity, and (3) degree of alteration (biodegradation; migration/fractionation; mixing). Several seafloor oil seeps recovered in piston cores at various deep-water sites were also analyzed and, in some instances, correlated to known production on the shelf. Samples included in this study are from onshore and offshore (Columbus Basin) Trinidad, Barbados, Guyana, and Suriname. Crude oil samples were characterized through the use of a detailed analytical program including gas chromatography, stable carbon isotopes, and quantitative biomarker analysis of saturate and aromatic fractions by gas chromatography/mass spectrometry (GC/MS). A regional framework was established by determining the number of distinct oil families. Source inferences with regard to age and paleoenvironment were made and source to oil correlations were established through comparison with source rock information mainly available from the literature. Oil chemistries were also used to identify complex processes determining oil quality which include, source facies variations, relative maturity, biodegradation, water washing, evaporative fractionation, gas stripping and remigration, and mixing of hydrocarbons. Detailed understanding of all these processes has important implications for exploration activity in the region. Analysis of >100 gas samples from major producing fields indicates variable mixtures of thermogenic and biogenic origin in the Columbus Basin. A mixing model based on gas hydrocarbon and isotopic compositions is used to identify areas of mixing.
Bio:
Craig Schiefelbein, Geochemical Solutions International, Inc.
Craig holds BS and MS degrees both from the University of Tulsa. He has 45 years of experience in the industry as Petroleum Geochemist.
He currently is Director of Geochemical Solutions International, Inc. in Houston, and is a member of AAPG, HGS, PESGB, EAOG and ALAGO.
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