The purpose of this study was to map the structure of scientific outputs of petroleum field in Science Citation Index (SCI) accessible via Web of Science (WOS) during 1990 to 2011 and determine the position of Iran. The used research methods were citation analysis and historiography. The results showed that there were totally 26859 records indexed in the petroleum discipline during 1990-2011 in SCI. USA, 7237 documents (27.28%), was the most collaborative country in this research. Iran with 321 documents ranked 21th country among all countries. The American author, Marshall A.G., with 85 documents ranked top among the most productive authors. In Iran, Kharrat from Petroleum University of Technology with 8 documents was the most productive Iranian author in petroleum field. Among the institutes and universities, Chinese Academy of Science was the most productive with 530 documents. Among the institutes and universities at national level, Tehran University has the first place with 53 documents. Energy & Fuels, Organic Geochemistry, and Abstracts of Papers of the American Chemical Society were the most important journals in terms of production and citation (both LCS and GCS) in petroleum field. The scientific map of petroleum field was drawn using HistCiteTM software. The analysis of the map revealed six thematic clusters including “Analysis and evaluation of compounds and elements of molecular structure of petroleum”, “Analysis and evaluation of compounds and elements of molecular structure of petroleum using mass spectrometry”, “reviewing and modeling of conditions of production and formation of source rock”, “survey of petroleum and its compounds biodegradation by bacteria and algae”, “survey of characteristics and history of petroleum reservoir”, and “survey of polycyclic aromatic hydrocarbons (PAHs)”.