| Jurassic source rocks develops in Right Bank of Amu Darya in Amu-Darya Basin(Turkmenistan) and owing to different content of TOC, they can be divided into the good source rock(the Upper Jurassic marine higher-gamma mudstone), the medium one (Upper Jurassic marine marlite) and the mid-poor one(Middle and Lower Jurassic coal-bearing mudstone) based on the evaluation standard of organic matter abundance rank of China. According to the source-rock correlation, the organic abundance in these source rocks from Right Bank is higher than that in the similar source rocks from different petroliferous basins in China (Tarim, Tuha, Sichuan and Bohaiwan basins), which implies good hydrocarbon-generating materials in the basin. The kerogen within the Jurassic marine source rock consists of high content of sapropel but possesses a low amount of hydrogen atom in it and so organic matter commonly comes from lower living beings such as algae. According to three indicators, i.e, kerogen H/C ratio, HI and δ13C, it is judged that the organic precursor of the Upper Jurassic marine source rock belongs to Type Ⅱto Type Ⅲof kerogen. The Upper Jurassic higher-gamma mudstone and marlite have entered into the peak stage of hydrocarbon generation(0.8%-1.3% Ro for 80% of samples), which is in favor of generating general oil, gas condensate and wet gas. The HC/TOC ratio reaches to 15.88%-18.4% that closes to the liquid hydrocarbon-producing rate of source rock with Type II kerogen,which indicates high potential of hydrocarbon generation in the Jurassic source rock. |
