塔里木盆地顺北地区奥陶系超深层原油裂解动力学及地质意义

Kinetics of oil-cracking of ultra-deep Ordovician oil in the North Shuntuoguole area of Tarim Basin and its geological implications

李慧莉 马安来 蔡勋育 林会喜 李建交 刘金钟 朱秀香 吴鲜

LI Huili MA Anlai CAI Xunyu LIN Huixi LI Jianjiao LIU Jinzhong ZHU Xiuxiang WU Xian

中国石化 石油勘探开发研究院, 北京 102206 中国石油化工集团有限公司 油田事业部, 北京 100728 中国科学院 广州地球化学研究所, 广州 510640 中国石化 西北油田分公司, 乌鲁木齐 830011

SINOPEC Petroleum Exploration & Production Research Institute, Beijing 102206, China Department of Oilfield Exploration & Development, SINOPEC, Beijing 100728, China Guangzhou Institute of Geochemistry, Chinese Academy of Science, Guangzhou, Guangdong 510640, China SINOPEC Northwest Oilfield Company, Urumqi, Xinjiang 830011, China

随着塔里木盆地海相油气勘探向深层的拓展，超深层油藏赋存温度上限是有机地球化学和石油地质学关注的科学问题。使用封闭体系黄金管热模拟实验方法，对塔里木盆地顺北7井奥陶系超深层原油开展了50 MPa、90 MPa两种压力和2℃/h、20℃/h两种升温速率的热模拟实验；根据模拟实验结果，应用Kinetics软件进行化学动力学计算，对比不同温压条件下原油热裂解进程，讨论其地质意义。结果表明，在不同温压条件下，同一原油具有基本相似的裂解过程和基本一致的终点温度裂解总生气量。在原油裂解中，早期有重烃气的生成，晚期重烃气进一步转化为甲烷。升温速率对原油裂解进程影响显著，较高的升温速率下，原油裂解进程向高温推移，并且具有较高的油相保存温度上限。压力对原油裂解的影响较小。同一升温速率条件下，裂解早期压力对原油热裂解稍有"抑制"作用，而裂解晚期，压力则稍有"促进"作用。原油在不同温压条件下裂解过程的差异，可以用裂解活化能分布的差异进行解释。顺北7井原油在两种压力条件下均具有相对集中的活化能分布，表明原油发生裂解转化过程的"温度窗"相对较窄。顺北一区油相保持的温度上限高于180℃，在埋深9 000 m的深部仍可保持油相。

With the expansion to the deep strata for the exploration of marine oil and gas in the Tarim Basin, the upper limit of temperature for the occurrence of ultra-deep reservoirs has become a scientific concerning of organic geochemistry and petroleum geology. Thermal simulations of the ultra-deep Ordovician oil from well SB 7 in the North Shuntuoguole area of Tarim Basin were carried out using a gold-tube confined system under two different pressures of 50 and 90 MPa and two different heating rates of 2 and 20℃/h, respectively. According to the results of simulation experiments, Kinetics software was used to calculate the chemical kinetics, and the mass yield of gas generation during oil-cracking under different temperature and pressure conditions was compared, and its geological significance was discussed. Under different temperature and pressure stages, the same oil sample experienced a similar process of oil-cracking as well as of total volume and mass yield of gas generation. Heavier gas compounts were generated in the early stage of oil-cracking and further transformed to form methane in the later stage. Heating rates impacted greatly on oil-cracking processes. Under a higher heating rate, the oil-cracking process moved to higher temperature and the separate oil phase can be kept with a higher temperature limit. High pressures only played minor roles on oil-cracking. With the same heating rate, higher pressure negligibly suppressed oil-cracking in the early stage of oil-cracking, whereas in the later stage, higher pressure promoted oil-cracking a bit. The difference of oil-cracking process under different temperatures and pressures can be explained by the distribution of activation energy. The distribution of activation energy of C1-C5 gas mass yield of oil-cracking of well SB 7 is relatively more concentrated, suggesting that the "temperature window" of oil-cracking is relatively narrower. According to the thermal simulation and kinetics calculation results, the maximum temperature of oil phase in the block 1 in the North Shuntuoguole area is greater than 180℃, and oil phase can be maintained at a depth greater than 9 000 m.

国家自然科学基金 U19B6003;国家自然科学基金 41772153;中国石化科技部项目 P19024-4;中国石化科技部项目 P21085-8

https://doi.org/10.11781/sysydz202105818