Hydrocarbon Generation in the Lacustrine Mudstones of the Wenchang Formation in the Baiyun Sag of the Pearl River Mouth Basin, Northern South China Sea

Abstract

The lacustrine mudstones of the Eocene Wenchang Formation are the primary source rocks of natural gas in the Baiyun Sag of the Pearl River Mouth Basin, China. The hydrocarbon generation kinetic parameters and the characteristics of lacustrine mudstones sampled from the Eocene Wenchang Formation at well LF13-2-1 were investigated on the basis of a thermocompression simulation experiment in a closed system. In addition, combined with the burial history and paleothermal history, the gas generation process of the Eocene Wenchang Formation source rocks in the Baiyun Sag was investigated through the hydrocarbon generation equations established from parameters of hydrocarbon generation kinetics. The gas generation process of the Eocene Wenchang Formation lacustrine mudstones has three thermal evolutionary stages: the middle mature stage (39−30 Ma), the late mature stage (30−23.5 Ma), and the main gas generation stage (23.5−0.0 Ma). The main hydrocarbon generation stage in the central area of the Baiyun Sag occurred from 24 Ma to 22 Ma, while the main hydrocarbon generation stage in the eastern and northern areas occurred at ∼15 Ma.

The nature of organic records in impact excavated rocks on Mars

“…Pyrolysis of the type I and II organic matter following pressure-temperature treatment produces only a few products: toluene, decane and phthalates, which are most likely laboratory or storage contaminants. This is in direct contrast to anhydrous confined pyrolysis experiments performed on Type I organic matter at 450 °C/16 hours, which showed the production of alkanes, aromatic and polar compounds 36 , a result consistent with similar 72 hour experiments run on Type I organic matter at 400 and 500 °C 37 . Anhydrous confined pyrolysis experiments on Type II organic matter showed the promotion of aromatization (e.g., the formation of naphthalenes, methylated naphthalenes, etc.)…”

Impact of Paleosalinity, Dilution, Redox, and Paleoproductivity on Organic Matter Enrichment in a Saline Lacustrine Rift Basin: A Case Study of Paleogene Organic-Rich Shale in Dongpu Depression, Bohai Bay Basin, Eastern China

“…The shale gas and oil revolution of North America changed the world energy structure and stimulated shale oil exploration and research in many other countries around the world. Precise prediction of “sweet spots” is one of the key musts for successful shale oil exploration. − Recent studies indicate that the organic matter content in a shale determines the hydrocarbon generation capacity of the shale, − affects the pore space development, ,− and strongly correlates to the residual hydrocarbon (adsorption) capacity. ,,,− Therefore, shale oil “sweet spots” and organic-rich intervals are closely related, − , and determination of the main factors controlling organic matter enrichment in shales is of great significance.…”

Characteristics and Hydrocarbon Generation of the Marine Source Rock of the Upper Oligocene Zhuhai Formation in the Baiyun Sag, Pearl River Mouth Basin, South China Sea

“…Organic matter type: The marine source rock of Upper Oligocene Zhuhai Formation came from the terrestrial higher plant with the organic matter types of II 2 and III. − The hydrogen index (HI) and the maximum peak temperature of pyrolysis ( T max ) can be used to characterize the organic matter type of a source rock . The mudstones of the Upper Oligocene Zhuhai Formation have relatively high values of HI and T max that are, mainly, indicative of type II 2 organic matter; thus, the mudstones of the Upper Oligocene Zhuhai Formation mainly contain type II 2 organic matter (Figure ).…”

“…The simulation experiments were performed by individual heating of the original samples (Zhuhai source rock) at separate temperature levels in a closed system . The experimental apparatus was a GCF-0.25L model (Liaoning, China). ,,− According to our test conditions, the heating time can be set to 24, 48, or 72 h when the simulation temperatures are less than or equal to 300 °C. When the simulation temperatures are equal or greater than 325 °C, − the heating time is usually set no more than 24 h because the kerogen cracking reactions are accelerating and the vitrinite reflectance value shows a positive correlation with time and temperature.…”