Introduction

Abstract

The primary purpose for studying palynology of petroleum sources, Petrolipalynology, is to determine geological ages and stratohorizons of petroleum source rocks. In accordance with theories on origin, migration, and accumulation of petroleum, fossil spores and pollen in crude oils should be from the source bed, the carrier bed, and the reservoir bed, thereby forming a three-part assemblage. The reservoir rock of an oil field is always known, so fossil spores and pollen deriving from the reservoir bed itself can easily be separated from the three-part assemblage. The remainder of the assemblage indicates source and carrier beds. Studies of the incorporated pollen and spores show that source rocks can be younger or older than the reservoir rocks. Although the geological circumstances are often complicated, petroleum source rocks can be judged by correlations between fossil spores and pollen in oils and those in potential petroleum source rocks. The fossil spores and pollen of petroleum source rocks can be carried to petroleum traps during the course of petroleum migration, because they are minute, light, flexible, and have a strong exine which can withstand such transport. Laboratory experiments on petroleum migration have demonstrated that microfossils entrapped by oil and gas from source rocks and carrier rocks can migrate together with oil and gas and that they can also be separated from oil and gas without any appreciable change in structural features.