Geochemical Characteristics of Synthetic Hydrocarbon Inclusions in Rock Salt-Crude Oil and Their Implication for Oil Source Comparison

Petroleum inclusions are widely used in hydrocarbon accumulation, but the lack of direct experimental evidence means that proof cannot be determined as to whether petroleum inclusions inherit the fluorescence and geochemical characteristics from crude oil. The petroleum inclusion in NaCl crystal is synthesized using the NaCl evaporation crystallization method under the open system and is reported in this paper. The fluorescence, composition and geochemical characteristics of synthesized petroleum inclusion and crude oil were studied by Microscope and Laser Ablation GC-MS. Three kinds of petroleum-bearing inclusions are identified at room temperature, such as liquid single-phase hydrocarbon inclusion, gas and liquid two-phase hydrocarbon inclusion, and gas, petroleum and water three-phase inclusion. These petroleum-bearing inclusions show yellow-green and blue-green fluorescence. The synthesized petroleum inclusions have lower content of light fractions in saturated hydrocarbons and aromatics than the crude oil. It can be inferred that the selective-capture of different compounds occur during the trapping process of synthesized petroleum inclusion. However, both the crude oil and synthesized petroleum inclusion show similar Pr/Ph ratios and the relative content of different types of compounds, which can be used to discriminate the sedimentary environment and other geochemical characteristics. Therefore, the geochemical composition of petroleum inclusion is still a powerful and reliable tool to trace the source rock of the crude oil, using the method described here.