Miao Huan, Wang Yanbin, Zhao Shihu, Guo Jianying, Ni Xiaoming, Gong Xun, Zhang Yujian, Li Jianhong
School of Geoscience and Surveying Engineering, China University of Mining and Technology, Beijing 100083, China.
Key Laboratory of Natural Gas Accumulation and Development, China National Petroleum Corporation, Langfang 065007, China.
ACS Omega. 2021 Nov 16;6(47):31578-31594. doi: 10.1021/acsomega.1c04061. eCollection 2021 Nov 30.
The Taodonggou group of Middle Permian is an important source rock in Taibei sag of Turpan-Hami basin. Due to its deep burial, drilling has only been revealed in recent years. Based on organic petrology and organic geochemistry experiments, this paper studies the organic petrology, organic geochemistry, sedimentary environment, and hydrocarbon generation potential of source rocks in Taibei sag, Turpan-Hami basin, and reveals the influence of the sedimentary environment on the organic matter abundance of source rocks. The results are as follows: (1) The organic matter of the Middle Permian source rocks in Taibei sag of Turpan-Hami basin is mainly sapropelite and exinite. The vitrinite is mainly vitrodetrinite, and the exinite is mainly lamalginiite. (2) The total organic carbon content value is 0.55-6.08 wt %, and the average value is 2.58 wt %. The PG value ranges from 0.78 mg HC/g to 30.86 mg HC/g, and the average value is 4.88 mg HC/g. Chloroform asphalt "A" is 0.046-0.8767 wt %, and the average value is 0.285 wt %. The types of organic matter are mainly III and II-III, and the value is 0.628-1.49 wt % (average = 0.988 wt %). The distribution is 329-465 °C. The average temperature is 434.7 °C, which is in the mature stage (oil window stage). The Middle Permian source rocks are mainly very good to excellent source rocks with a good hydrocarbon generation potential. (3) The source rocks are deposited in a semihumid and semiarid climate. Organic matter is input as a mixed source. The early and late stages is dominated by terrestrial higher plants. The middle stage is dominated by lower aquatic organisms, and the sedimentary environment consists of weak reduction and weak oxidation environments. (4) In the study area, the abundance of organic matter has a weak negative correlation with CPI and a positive correlation with Pr/Ph and ∑C-/∑C+. Under the coaction of paleoclimate, organic matter input, and redox environment, the enrichment model of organic matter with high productivity and weak oxidation environment characteristics can also form excellent source rocks. This study is of great significance and provides theoretical guidance for the exploration of deep oil and gas resources.
中二叠统桃东沟群是吐哈盆地台北凹陷重要的烃源岩。由于其埋藏较深，近年来才被钻探揭示。本文通过有机岩石学和有机地球化学实验，对吐哈盆地台北凹陷烃源岩的有机岩石学、有机地球化学、沉积环境及生烃潜力进行了研究，揭示了沉积环境对烃源岩有机质丰度的影响。结果表明：（1）吐哈盆地台北凹陷中二叠统烃源岩有机质主要为腐泥无定形体和壳质组，镜质组主要为碎屑镜质体，壳质组主要为层状壳质体。（2）总有机碳含量值为0.55 - 6.08 wt%，平均值为2.58 wt%。产气潜量值为0.78 mg HC/g至30.86 mg HC/g，平均值为4.88 mg HC/g。氯仿沥青“A”为0.046 - 0.8767 wt%，平均值为0.285 wt%。有机质类型主要为Ⅲ型和Ⅱ - Ⅲ型，氢指数值为0.628 - 1.49 wt%（平均 = 0.988 wt%）。主峰分布为329 - 465℃，平均温度为434.7℃，处于成熟阶段（生油窗阶段）。中二叠统烃源岩主要为很好 - 好的烃源岩，生烃潜力良好。（3）烃源岩沉积于半湿润 - 半干旱气候条件下，有机质为混合来源输入，早期和晚期以陆生高等植物为主，中期以下水生生物为主，沉积环境为弱还原 - 弱氧化环境。（4）研究区有机质丰度与CPI呈弱负相关，与Pr/Ph、∑C - /∑C +呈正相关。在古气候、有机质输入及氧化还原环境共同作用下，具有高生产力、弱氧化环境特征的有机质富集模式也可形成优质烃源岩。本研究具有重要意义，为深层油气资源勘探提供了理论指导。
