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Terpenoid hydrocarbons are ubiquitous in the marine environment and may be linked to natural synthetic activities after the original carbon skeleton of the biological precursor is retained. The terpenoid profile in pristine environments should have a biogenic signature. However, the widespread use of petroleum-derived products contributes to the inventory of hydrocarbons found in recent sediments, including the introduction of cyclic hydrocarbons with a thermogenic signature. Terpenoid hydrocarbons were examined from the mangrove sediments of the Paranagua Estuarine System (PES), which is a subtropical system in the South Atlantic. Intensive tourism has affected the PES, and it is at high risk of contamination due to extensive urban development and harbour activity. The biogenic compounds (BIO) in the PES were predominantly composed of unsaturated derivatives from higher plants (oleanoids, lupanoids, ursanoids and taraxeroids) with a des-A configuration and bacterial hopanoids. Thermogenic compounds (TRM) were distributed throughout the PES, and the sum of thermogenic and biogenic compounds exhibited a similar distribution, with significant correlations between these compounds. To better assess anthropogenic sources of hydrocarbons in mangrove, a ratio of TRM/BIO was proposed. Ratios higher than 1.0 were found near Paranagua port and in the Paranagua bay area. An important touristic destination, Mel Island, also exhibited ratios higher than 1.0 in two locations. The proposed terpenoids ratio accurately assessed the low-level chronic inputs of anthropogenic hydrocarbons in the study area. This innovative approach may be applied to areas with high biogenic inputs of organic matter, where chronic low-level hydrocarbon contributions are not evident using n-alkanes and polycyclic aromatic hydrocarbons.

Problems related to the crystallization and deposition of heavy organic fractions during production, transportation and storage of crude oils can lead to considerable financial losses for the petroleum industry. The heavy organic fractions may include paraffins or waxes, resins, asphaltenes, and organometallic compounds that exist in crude oils in various quantities, states, and forms. The severity of the deposition problems varies widely and depends on factors such as the crude oil composition, operating conditions in the reservoir and production procedures. Problems associated with the solid deposits may be encountered anywhere in the production process from the reservoir to the refinery. In this paper, it is proposed to focus on production problems associated with certain fields in Tunisia. The problems manifested themselves through the accumulation of solid deposits in the storage tanks at a Tunisian terminal and originated from the mixtures of various crude oils transported to the terminal by pipeline. The principal analytical method for the characterization of the solids was high temperature gas chromatography following concentration of the wax fraction through a modification of the conventional acetone precipitation technique.

Thirty oils from the Pauls Valley area of the Anadarko Basin, Oklahoma, have been analyzed for n-alkane, terpane and sterane distributions in an effort to classify genetically related oils. Ten rock samples from the area were also analyzed in an attempt to relate oil types to their possible source rocks. The Pauls Valley area, located near the southeast corner of the Anadarko Basin, has producing formations ranging in age from Middle Ordovician to Late Pennsylvanian. Trapping mechanisms responsible for the accumulation of hydrocarbons vary from purely structural traps, to fractured reservoirs, to up-dip truncations of reservoirs and up-dip pinchouts of sandstones. Results show that 85% of oils in the area probably have a common source, the Woodford Shale. A group of oils reservoired in the Viola Group exhibit distinct geochemical characteristics and are thought to have a different source. The differences between the oils from these two sources include: enhanced C24 tetracyclic terpane concentrations relative to C26 tricyclic terpanes; diminished C28–30 tricyclic terpanes relative to Ts and Tm; diminished C30-steranes relative to their C29 counterparts; predominance of C35 over C34 extended hopanes and an even/odd predominance of the normal alkane distribution. Extracts from the Viola Group generally exhibit the same qualities as the associated oils and the limestone is proposed as their probable source rock. The predominance of C29-steranes for oil samples which appear to have a marine source (inferred by their n-alkane distribution, the presence of C30-steranes and high levels of tricyclic terpanes) suggests that caution be used in the interpretation of terrigenous sources based on the high abundance of C29-steranes. The Deese Group, the Springer Formation, the Sylvan Shale, and the Arbuckle Group are not likely sources for the oils analyzed from the Pauls Valley area. Differences in API gravity and color, previously used to classify oils in this region, are not source-related but are related to maturation and migration effects.