Control effect of the gulf on marine petroleum

Abstract

Abstract About 80% of the discovered oil reserves in the world are generated from marine source rocks (about 20% from lacustrine source rocks), and the main control factors of reservoir formation are quite different for various oil-bearing basins. Whereas, as seen from global basins, the most important and most common accumulation control factor is the oil source, i.e. the “source control” is the most important factor. Through exploring the formation conditions of marine source rocks, the major marine basins in the world are well investigated. The result shows that the Persian Gulf Basin, Western Siberia Basin, Mexico Gulf Basin, North Sea Basin, Atlantic Ocean Basin, East Africa Coast Basin, Sichuan Basin, Tarim Basin and Paleo-Tethys Ocean and other basins were all gulfs during the formation period of the main source rocks, three sides of these gulfs are lands, and the major gulfs had only one water channel (a minority had two-three water channels) connected to the ocean. The gulf is the most favorable estuary for river. After passing through the weathered and denuded area, the river dissolves a large number of minerals, and bring some elements (such as P, Fe and K) to the gulf as the main nutrients for aquatic organisms (such as algae), however, nutrients brought by oceanic upwelling is unable to reach the gulf. Due to limited seawater replacement and exchange between gulf and ocean, the concentration of nutrients is high, and thus guaranteeing the long-term production of aquatic organisms (such as algae). Gentle winds and waves in the gulf were favorable for the preservation of organic matters, and thus high-quality source rocks were well developed. Relationship between modern marine and lake organisms and river, further confirm that the main nutrients for aquatic organisms growth are from rivers on the land.