Hydrocarbon Generation Evaluation, Burial History, and Thermal Maturity of the Lower Triassic–Silurian Organic-Rich Sedimentary Rocks in the Central Uplift of the South Yellow Sea Basin, East Asia

Abstract

This study focuses on the organic-rich rocks in the Central Uplift of the South Yellow Sea Basin (SYSB) using the CSDP-2 borehole, which was drilled through the integrated Lower Triassic–Silurian sediments and yielded approximately 2736 m of cores. Geochemical analyses of core samples, including Rock-Eval pyrolysis, elemental analysis, maceral analysis, and gas chromatography–mass spectrometry, revealed multiple sets of effective source rocks developed from the Lower Triassic Qinglong Formation to the Lower Silurian Gaojiabian Formation. The organic matter is dominated by types II1–2–III kerogen, most of which are mature to post-mature. Comprehensive geochemical analysis shows that Permian and Lower Carboniferous mudstones are the most important source rocks and have strong hydrocarbon generation capacity. Most of the source rocks are dominated by planktonic/bacterial sources, deposited mainly in a low-salinity marine environment, and influenced by the input of terrigenous detrital materials. Basin modeling results show that most of the Paleozoic–Mesozoic source rocks in the Central Uplift generally entered the oil-generation window during the Triassic to Late Jurassic. The timing of hydrocarbon generation and expulsion was simultaneous or earlier than the collisional orogenic movement between the Sino–Korean Platform and the Lower Yangtze Craton, which may have some destructive impact on the oil and gas preservation. Therefore, it is preservation condition rather than source rocks that may be one of the most important elements for hydrocarbon accumulation in the Central Uplift of the SYSB.

Formation Stages and Evolution Patterns of Structural Fractures in Marine Shale: Case Study of the Lower Silurian Longmaxi Formation in the Changning Area of the Southern Sichuan Basin, China

“…However, late tectonic activities are frequently adjusted. Tectonic evolution and tectonic patterns have extremely important influences on the reformation and formation of oil and gas reservoirs. ,− According to the results of historical studies on existing hydrocarbon generation, the Changning area and its peripheries entered the wet gas generation stage during the Late Triassic (210 Ma). The Early Yanshanian movement (185 Ma) entered the dry gas stage (Figure ).…”

Tectonic Fracture Formation and Distribution in Ultradeep Marine Carbonate Gas Reservoirs: A Case Study of the Maokou Formation in the Jiulongshan Gas Field, Sichuan Basin, Southwest China

“…According to the analysis of thermal evolution history of the well, the uplift and denudation time of the area can be analyzed and the tectonic stage can be judged. , In combination of the regional tectonic evolution and the burial–thermal history (Figure ), the study area has undergone three major tectonic stages since the Indosinian stage. They are the Indosinian stage (232–210 Ma), the early middle Yanshanian stage (145–90 Ma), and the late Yanshanian to Himalayan stage (90–0 Ma).…”

“…According to the analysis of thermal evolution history of the well, the uplift and denudation time of the area can be analyzed and the tectonic stage can be judged. 42,43 In combination of the regional tectonic evolution and the burial−thermal history (Figure 12), 44 mainly formed. That is, the NE trending fold was formed; the tectonic activity was weak; and the fractures and faults were not developed.…”

Characteristics and vertical zonation of large‐scale granitic reservoirs, a case study from Penglai oil field in the Bohai Bay Basin, North China

“…The characteristics of trace elements in rocks are of great significance to the analysis of sedimentary environment (Pang et al, 2020). The chemical behaviour of elements is different in the oxidation zone near surface, leading to the element contents in WZ are obviously different (Chen et al, 2016; Islam, Rojst, Aario, & Vesa, 2002).…”