Application of trace elements in the study of oil-source correlation and hydrocarbon migration in the Tarim Basin, China

Oil source and hydrocarbon migration are critical in the study of hydrocarbon accumulation. Under the complicated conditions of hydrocarbon accumulation, traditional organic geochemistry has its limitation. Therefore, the purpose of this study is to try a new way to investigate hydrocarbon accumulation and migration. The occurrence of trace elements in crude oil and their activation and migration were studied. The fingerprint of trace elements was discussed. Our results indicate that rare earth elements and transition metals could be used for study of oil-source under the complicated conditions of hydrocarbon accumulation and migration. V/Ni ratio was a specific indicator in tracing hydrocarbon migration pathway. Tarim Basin, a typical complex superimposed basin in west China was studied. The result indicated that crude oil from the Ordovician in Tazhong (central Tarim) low uplift was characterized by mixed sources. The contributions of individual sources differed from formation to formation and from block to block. The distribution of underground fluid was significantly controlled by large-scale strike-slip faults. Our study result is consistent with the knowledge of field geologists. Application of trace elements as indicators is an effective method to study hydrocarbon accumulation and migration.