Characteristics, controls and geological models of hydrocarbon accumulation in the Carboniferous volcanic reservoirs of the Chunfeng Oilfield, Junggar Basin, northwestern China

Abstract

The Junggar Basin is one of the most important basins for hydrocarbon production in China. Within the basin, the Chunfeng Oilfield forms one of the most important oilfields of the area. Despite the significant work that has been done on the rocks of the oilfield so far, a detailed reservoir characterization and description of the hydrocarbon accumulation pattern was still missing. Therefore, an investigation had been initiated to fill this gap in our understanding of the hydrocarbon reservoirs of the 2 ACCEPTED MANUSCRIPT Junggar Basin. The results of this study show that the tuff and andesitic lava lithofacies exhibit the highest reservoir potential in the area. Apart from the lithofacies, the results of this study show that tectonic (formation of fault systems) and diagenetic (formation of solution pores) effects, and the development of a weathering crust are crucial factors that control the quality of the petroleum reservoirs of the oilfield. In addition, two possible geological models of petroleum accumulation in isolated volcanic rocks and sandstone (IVRS) and connected volcanic rocks and sandstone (CVRS) are presented.

Charging history and fluid evolution for the Carboniferous volcanic reservoirs in the western Chepaizi Uplift of Junggar Basin as determined by fluid inclusions and basin modelling

“…As shown in Figure , the hydrocarbon accumulation model for western Chepaizi Uplift was established as follows: At first, the Jurassic source rocks of Sikeshu Sag generated hydrocarbon in late Paleogene period, and then under the occlusion of the Upper Cretaceous regional mudstone caprock, the hydrothermal fluid containing hydrocarbon migrated to the Aika Fault Belt (F 2 section) vertically (Wang et al, ). The sheet sandbodies of the Middle Jurassic Toutunhe Formation (J 2 t) and the unconformities between the Carboniferous/Cretaceous acted as pathway of lateral migration.…”

“…The Junggar Basin, a large intermontane superimposed basin, located in the Xinjiang Uygur Autonomous Region of Northwest China, covers a total area of 136,000 km 2 (Wang et al, ). The Hashan Block in the north part, Kelamayi Block in the central part and, Chepaizi Block in the south part are the three main petroleum productive areas in the Junggar Basin (Hu et al, ).…”

The dead line for oil and gas and implication for fossil resource prediction

“…Previous geochemical and sedimentological data demonstrate that the source rocks are mainly Permian shales and that the main reservoirs are the clastic rocks in the Permian, the Triassic, and the Jurassic formations capped by the Upper Triassic, the Lower Jurassic, and the Lower Cretaceous mudstones, respectively (Cao et al, 2005). A few Carboniferous volcanic reservoirs are found distributed in structural highs near fault zones and unconformities, and the hydrocarbons in these reservoirs are also primarily derived from the Permian shales (Chen et al, 2016;Wang et al, 2018). According to the analyses of fluid inclusions and basin modeling, the Permian source rocks have started generating hydrocarbons since the Middle Permian-Late Permian due to a rifting-process-related high heat flow, and the main hydrocarbon accumulation period spanned from the Triassic to the Paleogene for the whole basin (Wang et al, 2001;Cao et al, 2005).…”

Bio-Precipitation of Calcium and Magnesium Ions through Extracellular and Intracellular Process Induced by Bacillus Licheniformis SRB2

“…In fact, the mineral precipitation process mediated by organic components occupies an important position in both present and ancient environments [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70]. The adsorption of Ca 2+ and Mg 2+ ions on the bacterial cell surface is the initial step of biomineralization.…”