Publications

In recent years, petroleum geochemists have been refocussing their efforts on developing practical means for inferring, from hydrocarbon chemistry and geologic constraints, the ",provenance", of hydrocarbon accumulations, seeps or stains. This capability, referred to here as ",Geochemical Inversion",, can be invaluable to the explorationist in deriving clues as to the character, age, identity, maturity and location of an accumulation's source rocks and in evaluating a petroleum system's hydrocarbon supply volumetrics: This is particularly true where pertinent source-rock' information may be absent because exploratory drilling focused strictly on structural highs and failed to penetrate the deeply buried, effective basinal source facies. Advances in chemical analysis technology over the last decade have facilitated the development of powerful geochemical methods for deconvolution of complex chemistries of crude oil and natural gas at the molecular and subatomic levels to extract specific information on the hydrocarbons' source. Inferences on such factors as organic matter make-up, depositional environment, lithology, age and maturity of the source can frequently be drawn. These, together with a sound analysis of the geologic and architectural constraints on the system, can supply clues as to the identity and location of the probable source sequence. This paper describes the principles underlying geochemical ",inversion", and provides examples of its application in exploration and exploitation settings.Inversion of geochemical characteristics of migrated hydrocarbon fluids to specific attributes of the source is demonstrated. The paper will also illustrate the utilization of systematic variations in fluid chemistry within a geologic setting to infer source location, degree of hydrocarbon mixing and relative migration distance.