四川盆地北部上三叠统须家河组煤系烃源岩生烃史

为准确认识四川盆地北部上三叠统须家河组天然气成藏过程，基于近年来煤系烃源岩生排烃特征研究的最新进展和盆地模拟技术，对该区煤系烃源岩埋藏热演化史、生烃史进行了系统研究。首先，分别建立了盆地的地质、热力学和生烃动力学模型，其次，选取古水深、沉积水界面温度、古热流值作为模拟参数，对该区17口钻井进行了模拟。结果表明：①须家河组烃源岩生气时段发生在快速沉降阶段，总体表现为快速生气的特点，元坝地区的生气时间略早于通南巴地区；②须家河组烃源岩在中侏罗世中期Ro达到0.6%，开始生气，中侏罗世晚期-晚侏罗世Ro达到0.7%，开始大量生气，晚侏罗世-早白垩世Ro达到1.0%，进入生气高峰期；③随着埋深进一步增大（在早白垩世末期达到最大埋深），烃源岩进入高-过成熟阶段，至晚白垩世盆地整体大幅度抬升，地温降低，逐渐停止生烃。

Hydrocarbon generation history of coal measure source rocks in the upper Triassic Xujiahe Formation of the northern Sichuan Basin

In order to accurately identify the process of gas accumulation in the upper Triassic Xujiahe Formation of the northern Sichuan Basin, the burial and thermal evolution history and hydrocarbon generation history of the coal measure source rocks in this area are systematically analyzed based on the latest research results of hydrocarbon generation characteristics of coal measure source rocks and basin modeling in recent years. First, we established geologic, thermodynamic and hydrocarbon generation dynamic models of this basin. Then, we simulated 17 wells in the study area with paleobathymetric data, sediment water interface temperature, and ancient heat flow being input parameters. The following results were obtained. (1) Gas generation from the source rocks in the Xujiahe Formation occurred in the process of rapid subsidence with a high speed as a whole. And gas generation in the Yuanba area is slightly earlier than that in the Tongnanba area. (2) Ro of the Xujiahe Formation source rocks reached 0.6% in the middle stage of the Middle Jurassic when gas was initially generated, and reached 0.7% in the late Middle Jurassic Late Jurassic when a huge quantity of gas was generated, and it finally reached 1.0% at the Late Jurassic Early Cretaceous when gas generation peak occurred. (3) The source rocks entered into high to post mature stages along with the increasing of burial depth (and reaching the maximum at the end of Early Cretaceous), when it came to the Late Cretaceous, the whole basin was uplifted greatly, the strata temperature became lower, and gas generation ceased gradually.