Geochemical Properties of Condensate Fluids in Kangan and Upper Dalan Formations in some of the Gas Reservoir Located at the Persian Gulf Border

Gas condensate reservoirs are generally deeper and are found at higher pressures and temperatures relative to oil reservoirs. Light hydrocarbon compounds are parts of crude oil and gas condensates, which have different types of structures. 7-carbon hydrocarbons with open chain and branch ring structures can be considered as good indicators for the recognition and origin of organic matters, source rock characteristics, etc. In this study, three fluid samples of three independent gas fields in southern Iran, from Kangan and upper Dalan formations (with similar geochemical characteristics), are subjected to detailed hydrocarbon analysis (with the ability of the identification of molecular components of the organic compounds) and other PVT experiments, and changes in the concentration of specific compounds having 7 carbons or less in different reservoir conditions were studied. The results showed that according to the overall parameters, samples A and C were similar and both were different from sample B, which was attributed especially to the difference of reservoir conditions between samples A and C with sample B. Also, the paraffinicity property of fields initially decreased but then increased from A to C, and, likewise, field B represented vast evidence for the occurrence of biodegradation processes. Figures showed that the source rock of sample C had obviously the terrigenous origin, but understanding the origin of samples A and B were carried out using various diagrams and it was determined that the two fields had the dry origin. It was also found that the mixing process of reservoir contents having organic matters with that of the other formations have probably occurred in sample C.