银根—额济纳旗盆地主力烃源岩生烃热模拟实验研究

银根—额济纳旗盆地下白垩统巴音戈壁组二段普遍发育一套湖相烃源岩，勘探证实这套烃源岩对油气成藏贡献很大，为盆地内主力烃源岩。黄金管—高压釜限定体系热模拟实验表明，巴音戈壁组二段样品的总烃累计产率为265.50～798.06 mg/g，“生油窗”内（模拟镜质组反射率EasyR_o=0.7%～1.5%）的总油产率为263.99～778.74 mg/g，大量生气阶段（EasyR_o>1.5%）的气态烃产率为191.19～582.69 mL/g，预示着这套源岩具有较高的生油气潜力。依据热模拟烃类产物的产率变化特征，可分为4个主要成烃演化阶段:（1）干酪根热解生油阶段，EasyR_o=0.57%～0.8%（样品热模拟的起始EasyR_o为0.57%），该阶段以干酪根热解生油为主；（2）凝析油生成阶段，EasyR_o=0.8%～1.5%，以早期生成的油裂解为轻烃和干酪根裂解生气为特征；（3）油裂解生气阶段，EasyR_o=1.5%～3.3%，此阶段以早期生成的油裂解生气为主；（4）气裂解阶段，EasyR_o>3.3%，以C_2-5裂解成甲烷为特征。 

Pyrolysis hydrocarbon generation of the main source rock in Yin'gen-E'ji'naqi Basin

Lacustrine source rocks are widely developed in the second member of Bayingebi Formation of the Lower Cretaceous (K₁b2) in the Yin'gen-E'ji'naqi Basin, and they are the main petroleum source rocks in the basin. Pyrolysis experiments show that the total hydrocarbon yield of the samples is 265-798 mg/g, the oil yield is 264-779 mg/g in the "oil window" (EasyR_o of 0.7%-1.5%), and the yield of gaseous hydrocarbon during the main gas generation stage (EasyR_o>1.5%) is 191-583 mL/g, which indicates that the source rocks not only have a high oil generation potential, but also have a high gas potential. The variation of hydrocarbon products during the pyrolysis experiments allow the thermal evolution of organic matter of source rocks to be divided into four main stages. The first stage is kerogen pyrolysis and oil generation stage, with an EasyR_o of 0.57%-0.8% (the initial EasyR_o of pyrolysis experiment is 0.57%). Kerogen pyrolyzes into oil. The second stage is the condensate oil generation stage, with an EasyR_o of 0.8%-1.5%. Early oil cracks into light hydrocarbons and kerogen cracks into gas. In the third stage, oil cracks into gas, with an EasyR_o of 1.5%-3.3%. The fourth stage is the gas cracking stage, with an EasyR_o more than 3.3%. C_2-5 cracks into methane.