POLYGENETIC SOURCES OF TRACE ELEMENTS IN OILS

Abstract

This paper reviews the problems concerning the origins of trace elements in oil. A polygenetic nature of elements in naphthides is suggested from the great deal of evidence including both published and original analytical data. The trace element contents of oils of various petroleum provinces are considered, and their relation to sedimentation and oil formation is demonstrated. Special attention is focused on V and Ni as the main trace elements in all naphthides. The relationships between trace element contents and physicochemical properties of oils are pointed out. The laboratory studies show that the rock-forming elements and some part of V and Fe under certain conditions can migrate into oil from host rocks and formation water. La, Eu, Hg, As, and Sb distribution in oils is discussed. These elements could ascend from deep crustal zones and be absorbed by oil. Thus, the trace elements in oils could be inherited from the living substance, extracted by oil from host rocks and formation water, or derived from mantle zones and transported through permeable conduits.