Hydrocarbon migration through salt: evidence from Kelasu tectonic zone of Kuqa foreland basin in China

Abstract

Halite and other evaporates are rarely observed to degrade via brittle faulting because of their ductile properties. Hydrocarbons resulting from fractures and faults are rarely found in salt structures. However, large-scale hydrocarbons resulting from faulting are not well-documented. The Dabei Gasfield, which produces natural gases with few condensate oils, is found under Paleogene evaporates in the Kelasu tectonic zone of the Kuqa foreland basin. Above these evaporates, the Dawanqi Oilfield produces oils with few natural gases in the Kelasu tectonic zone of the Kuqa foreland basin. The biomarker distribution from oils and carbon isotope from natural gases between the Dabei Gasfield below evaporates and the Dawanqi Oilfield above evaporates are very similar, which indicates that they have same hydrocarbon source. The results provide direct evidences of the rare migration of hydrocarbon through salt due to fractures and faults to form oil reservoirs above the salt. This study indicates that hydrocarbons occasionally exhibit widespread migration through salt due to extensive brittle faulting.