准噶尔盆地南缘侏罗系煤岩生烃动力学研究  

Petroleum generation kinetics of Jurassic coals in the southern margin of the Junggar Basin

作　　者：曾立飞 靳军[3] 马万云[3] 于双[1] 潘长春[1] ZENG Li-fei;JIN Jun;MA Wan-yun;YU Shuang;PAN Chang-chun(State Key Laboratory of Organic Geochemistry,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China;Research Institute of Experiment and Testing,Xinjiang Oilfield Company,PetroChina,Karamay 834000,China)

机构地区：[1]中国科学院广州地球化学研究所有机地球化学国家重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]中国石油新疆油田公司实验检测研究院,新疆克拉玛依834000

出　　处：《地球化学》2021年第3期282-293,共12页Geochimica

基　　金：国家自然科学基金(41572107);中国科学院A类战略性先导科技专项(XDA14010104)。

摘　　要：应用金管-高压釜装置对采自准噶尔盆地南缘西部煤样JC25和东部煤样JC41进行生烃动力学模拟实验,获取生油、生气量和生烃动力学参数。升温速率分别为2℃/h和20℃/h,实验压力为50 MPa。实验得到两个煤样JC25和JC41最大生油量(以下单位mg/g均表示每克有机碳的生成量)分别为126 mg/g和68.5 mg/g,计算的排油量分别为88.8 mg/g和29.5 mg/g,表明侏罗系煤岩在南缘西部四棵树凹陷较其他区域具有较大的生油潜力。两个煤样最大生气量(∑C1–5)分别为121.6mg/g和112mg/g,差异相对较小。煤样JC25和JC41的H/C原子比值分别为0.85和0.77,类脂组含量分别约为8%和6%,岩石热解(Rock-Eval)参数氢指数(IH)分别为155 mg/g和156 mg/g。实验结果表明, H/C原子比值、类脂组含量比IH能更好地反映煤岩的初始生油、生气潜力。依据生烃动力学参数模拟了地质条件下(升温速率5℃/Ma)的生油和生气过程。煤样主要生、排油阶段的Ro, Easy介于0.80%~1.20%之间。在半开放条件下(发生排油),两个煤样的生气速率比较接近。在Ro, Easy=1.50%时生气转化率分别为23%和18%,煤岩主要生气过程发生在高过成熟阶段(Ro,Easy>1.50%)。侏罗系烃源岩在霍玛吐背斜带中部成熟度较高,较其他区域具有更大的天然气勘探潜力。Confined pyrolysis experiments(in gold capsules) were performed at heating rates of 20 ℃/h and 2 ℃/h and a pressure of 50 MPa to determine the yields and kinetic features for petroleum formation for the coals JC25 and JC41 that were collected from the southwestern and southeastern margins, respectively, of the Junggar Basin. Coals JC25 and JC41 had maximum oil yields of 126.0 mg/g and 68.5 mg/g, and the maximum amount of expelled oil was 88.8 mg/g and 29.5 mg/g, respectively, determined from the pyrolysis experiments. This result suggests that the Jurassic coals in the Sikeshu Sag in the western region have higher oil generative potentials than coals in the other areas of the southern margin of the Junggar Basin. These two coals showed relatively similar maximum gas yields(∑C1–5) of 121.6 mg/g and 112.0 mg/g, respectively. Coals JC25 and JC41 had H/C atomic ratios of 0.85 and 0.77, liptinite contents of ~8% and ~6%, and Rock-Eval hydrogen indices(IH) of 155 mg/g and 156 mg/g, respectively. Therefore, H/C atomic ratio and liptinite content were more effective indicators of oil and gas generative potential for the coals, compared with HI value. Oil and gas generation and expulsion were modeled under a heating rate of 5 ℃/Ma using the kinetic parameters for these two coals determined from the pyrolysis experiments. Oil generation and expulsion from the two coals was primarily within the interval between Ro, Easy at 0.80% and 1.20%. In a semi-open system with efficient oil expulsion, the gas generation rates for these two coals are similar. At Ro, Easy of 1.50%, the transformation ratios for gas generation are 23% and 18% for JC25 and JC41, respectively. The majority of gaseous hydrocarbons were generated at a highly post mature stage(Ro, Easy > 1.50%). The Jurassic coal source rocks have higher maturities in the central Homatu anticline zone;therefore, this region is more favorable for gas exploration than the other regions in the southern margin of the Junggar Basin.

关 键 词：侏罗系煤岩 生烃动力学 生排油量 气态烃产率 准噶尔盆地南缘 

分 类 号：P593[天文地球—地球化学]