Influence of carbonate minerals on the pyrolysis and phase behavior of oil. (December 2021)

• Record Type: Journal Article
• Authors: Wu, Liangliang; Fang, Xinyan; Geng, Ansong
• Is Part Of: Marine and petroleum geology. Volume 134(2021)
• Publication Date: 2021-12
• Subjects: Carbonate mineral -- Catalytic effect -- Oil pyrolysis behavior; Submarine geology -- Periodicals; Petroleum -- Geology -- Periodicals; Géologie sous-marine -- Périodiques; Pétrole -- Géologie -- Périodiques; Petroleum -- Geology; Submarine geology; Periodicals; Electronic journals; 551.468
• DOI: 10.1016/j.marpetgeo.2021.105374
• Languages: English
• ISSNs: 0264-8172

Abstract

Abstract: The concept that reservoir minerals can affect oil cracking behavior is widely accepted by geochemists. However, the role of carbonate minerals on the thermal evolution of oil is still not well understood. This is especially true for dolomite, which is one of the most important carbonate cements. To investigate its influence, a series of laboratory simulation experiments of a crude oil with various carbonate minerals, including calcite, magnesite, and dolomite was conducted. The simulation experiments were carried out using a closed system of flexible gold capsules at temperatures of 250–600°С at a heating rate of 20 °C/h and a constant pressure of 50 MPa. The results indicate that dolomite/magnesite might promote the generation of sulfate radical ion (SO4 2− ). Subsequently, the presence of SO4 2− can initiate thermochemical sulfate reduction reaction with the help of minor water and H2 S, resulting in the destruction of gaseous hydrocarbons. Meanwhile, the influence of dolomite on the composition of oil can further affect its phase behavior, especially in the gas window (Easy Ro range of 1.19–1.47% in the experiments). For the investigated oil, at Easy Ro of 1.47%, the presence of dolomite will increase the cricondentherm (ca. 35 °C) and decrease the cricondenbar (ca. 1.3 MPa) compared to those of pure oil. Highlights: Pyrolysis of oil with various carbonate minerals was carried out. Dolomite has strong influence, while calcite has limited influence. Dolomite promotes the generation of SO4 2− and the cracking of gaseous hydrocarbons. Dolomite affects the PVT phase behavior of oil at EasyRo in the range of 1.19–1.47%. PVT phase analysis still needs to consider the mineral composition.