盖层封堵油气的机理研究
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摘要
盖层在油气成藏过程中起着十分重要的作用,为了搞清盖层的封堵机理,应用石油地质、油层物理和流体力学的相关知识对其进行了深入研究。结果表明:盖层是通过毛管压力封堵油气的,地层的非均质性越强,盖层与储层的毛管压力差值越大,能够封堵和聚集的油气数量就越多,均质地层不能聚集油气。地层的非均质性成就了石油工业。油气可以从烃源岩小孔隙运移进入储集岩大孔隙,却不能从储集岩大孔隙运移进入盖层小孔隙,这就是油气运移的奇妙之处。岩石的润湿性对油气封堵也十分重要,亲油岩石不能封堵油气,亲水岩石才能封堵油气。岩石的亲水性成就了石油工业。盖层中水的烃浓度极低,不可能超过油气藏的烃浓度,因而也不能对油气进行烃浓度封堵。盖层能够封堵油气,却不能封堵地层水;盖层能够封堵油气相,却不能封堵油气分子。盖层超压是用等效深度法计算出的结果,是一个假象,并非真的超压,也不可能对油气进行超压封堵。
Underground accumulation of oil and gas is the result of cap-rock's sealing. Without the sealing of caprocks, oil and gas will migrate to the earth's surface and be lost away. Therefore,cap-rocks play an important role in the accumulation of oil and gas. In order to clarify the sealing mechanism of cap-rocks,a deep study was carried out based on the related knowledge of petroleum geology,petrophysics and fluid mechanics,which reached the following conclusions. Cap-rocks seal oil and gas by capillary pressure. The stronger the heterogeneity of formations is,the larger the capillary pressure differential between the cap-rock and the reservoir rock will be,and the more the oil and gas can be sealed by the cap-rocks. Homogeneous formations cannot accumulate oil and gas. The heterogeneity of formations has made the petroleum industry. Oil and gas can migrate from the smaller pores of hydrocarbon source rocks into the larger pores of reservoir rocks,but cannot migrate from the larger pores of reservoir rocks into the smaller pores of cap-rocks,which is the marvelous point of oil and gas migration. The wettability of rocks is also very important. The oil-wet rocks cannot seal oil and gas,while the water-wetrocks can do. The water-wettability of rocks has made the petroleum industry. The hydrocarbon concentration of water is quite low in cap-rocks,being impossibly higher than that in reservoirs,so the hydrocarbon concentration sealing of cap-rocks cannot take place. Cap-rocks can seal oil and gas rather than formation water,and cap-rocks can seal the phase of oil and gas rather than the molecules of oil and gas, which is the marvelous point of sealing mechanism of cap-rocks. Overpressure of cap-rocks is calculated by the equivalent depth method,which is a misleading appearance. Cap-rocks are not really overpressured,so they cannot apply overpressure sealing to oil and gas.
Underground accumulation of oil and gas is the result of cap-rock's sealing. Without the sealing of caprocks, oil and gas will migrate to the earth's surface and be lost away. Therefore,cap-rocks play an important role in the accumulation of oil and gas. In order to clarify the sealing mechanism of cap-rocks,a deep study was carried out based on the related knowledge of petroleum geology,petrophysics and fluid mechanics,which reached the following conclusions. Cap-rocks seal oil and gas by capillary pressure. The stronger the heterogeneity of formations is,the larger the capillary pressure differential between the cap-rock and the reservoir rock will be,and the more the oil and gas can be sealed by the cap-rocks. Homogeneous formations cannot accumulate oil and gas. The heterogeneity of formations has made the petroleum industry. Oil and gas can migrate from the smaller pores of hydrocarbon source rocks into the larger pores of reservoir rocks,but cannot migrate from the larger pores of reservoir rocks into the smaller pores of cap-rocks,which is the marvelous point of oil and gas migration. The wettability of rocks is also very important. The oil-wet rocks cannot seal oil and gas,while the water-wetrocks can do. The water-wettability of rocks has made the petroleum industry. The hydrocarbon concentration of water is quite low in cap-rocks,being impossibly higher than that in reservoirs,so the hydrocarbon concentration sealing of cap-rocks cannot take place. Cap-rocks can seal oil and gas rather than formation water,and cap-rocks can seal the phase of oil and gas rather than the molecules of oil and gas, which is the marvelous point of sealing mechanism of cap-rocks. Overpressure of cap-rocks is calculated by the equivalent depth method,which is a misleading appearance. Cap-rocks are not really overpressured,so they cannot apply overpressure sealing to oil and gas.
引文
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[10]李传亮,张景廉,杜志敏.油气初次运移理论新探.地学前缘,2007,14(4):132-142.LI C L,ZHANG J L,DU Z M. New viewpoints of the primary migration of oil and gas. Earth Science Frontiers,2007,14(4):132-142.
[11]李传亮.气水可以倒置吗?岩性油气藏,2010,22(2):128-132.LI C L. Gas and water distribution can be inverted? Lithologic Reservoirs,2010,22(2):128-132.
[12]周兴熙.塔里木盆地克拉2气田成藏机制再认识.天然气地球科学,2003,14(5):354-361.ZHOU X X. Recognition on reservoir-forming mechanism of Kela 2 gas field in Tarim Basin. Natural Gas Geoscience,2003,14(5):354-361.
[13]李传亮地层异常压力原因分析.新疆石油地质,2004,25(4):443-445.LI C L. Analysis of abnormal reservoir pressure. Xinjiang Petroleum Geology,2004,25(4):443-445.
[14] MATTHEWS M D. Hydrocarbon migration:a view from the top. AAPG Memoir 66,1996:139-155.
[15] PRICE L C. Aqueous solubility of petroleum as applied to its origin and primary migration. AAPG Bulletin,1976,60(2):213-244.
[16]李传亮.岩石欠压实概念质疑.新疆石油地质,2005,26(4):450-452.LI C L. Discussion of undercompaction of rocks. Xinjiang Petroleum Geology,2005,26(4):450-452.
[17]刘向君,刘堂晏,刘诗琼.测井原理及工程应用.北京:石油工业出版社,2006:43-46,116-118.LIU X J,LIU T Y,LIU S Q. Principle and engineering application of well logging. Beijing:Petroleum Industry Press,2006:43-46,116-118.
[18]丁次乾.矿场地球物理.东营:石油大学出版社,1992:342-344.DING C Q. Field geophysics. Dongying:Press of University of Petroleum,China,1992:342-344.
[19] ZHANG J C. Effective stress,porosity,velocity and abnormal pore pressure prediction accounting for compaction disequilibrium and unloading. Marine&Petroleum Geology,2013,45(4):2-11.
[20]齐亚林,惠潇,梁艳,等.平衡深度法恢复鄂尔多斯盆地延长组过剩压力探讨岩.石油地质与工程,2014,28(5):20-22.QI Y L,HUI X,LIANG Y,et al.Equilibrium depth method to restore Yanchang formation pressure of Ordos Basin. Petroleum Geology and Engineering,2014,28(5):20-22.
[2]曹跃,刘延哲,陈义国,等.鄂尔多斯盆地东韩油区延长组长7—长9油气成藏条件及主控因素.岩性油气藏,2018,30(1):30-38.CAO Y,LIU Y Z,CHEN Y G,et al. Hydrocarbon accumulation conditions and main controlling factors of Chang 7-Chang 9oil reservoirs of Yanchang Formation in Donghan region,Ordos Basin. Lithologic Reservoirs,2018,30(1):30-38.
[3]杨元亮,朱筱敏,马瑞国,等.准噶尔盆地新春地区新近系油气富集规律.岩性油气藏,2017,29(4):20-29.YANG Y L,ZHU X M,MA R G,et al.Hydrocarbon accumulation rules of Neogene in Xinchun area,Junggar Basin. Lithologic Reservoirs,2017,29(4):20-29.
[4]李富恒,侯连华,石磊,等.花岗岩油气藏成藏富集因素.岩性油气藏,2017,29(1):81-89.LI F H,HOU L H,SHI L,et al.Accumulation and enrichment factors of granite reservoirs. Lithologic Reservoirs,2017,29(1):81-89.
[5]张厚福,方朝亮,高先志,等.石油地质学.北京:石油工业出版社,1999:120-135.ZHANG H F,FANG C L,GAO X Z,et al.Petroleum geology.Beijing:Petroleum Industry Press,1999:120-135.
[6]李明诚.石油与天然气运移. 3版.北京:石油工业出版社,2004:156-161.LI M C. Oil and gas migration. 3rd ed. Beijing:Petroleum Industry Press,2004:156-161.
[7] TIAB D,DONALDSON E C. Petrophysics. 3rd ed. Gulf Professional Publishing,Elsevier,2012:327-343.
[8]李传亮.地下没有亲油的岩石.新疆石油地质,2011,32(2):197-198.LI C L. There is no oil-wet rock underground. Xinjiang Petroleum Geology,2011,32(2):197-198.
[9]李传亮.地下岩石的润湿性分析.新疆石油地质,2013,34(2):243-245.LI C L. Wettability of underground rocks. Xinjiang Petroleum Geology,2013,34(2):243-245.
[10]李传亮,张景廉,杜志敏.油气初次运移理论新探.地学前缘,2007,14(4):132-142.LI C L,ZHANG J L,DU Z M. New viewpoints of the primary migration of oil and gas. Earth Science Frontiers,2007,14(4):132-142.
[11]李传亮.气水可以倒置吗?岩性油气藏,2010,22(2):128-132.LI C L. Gas and water distribution can be inverted? Lithologic Reservoirs,2010,22(2):128-132.
[12]周兴熙.塔里木盆地克拉2气田成藏机制再认识.天然气地球科学,2003,14(5):354-361.ZHOU X X. Recognition on reservoir-forming mechanism of Kela 2 gas field in Tarim Basin. Natural Gas Geoscience,2003,14(5):354-361.
[13]李传亮地层异常压力原因分析.新疆石油地质,2004,25(4):443-445.LI C L. Analysis of abnormal reservoir pressure. Xinjiang Petroleum Geology,2004,25(4):443-445.
[14] MATTHEWS M D. Hydrocarbon migration:a view from the top. AAPG Memoir 66,1996:139-155.
[15] PRICE L C. Aqueous solubility of petroleum as applied to its origin and primary migration. AAPG Bulletin,1976,60(2):213-244.
[16]李传亮.岩石欠压实概念质疑.新疆石油地质,2005,26(4):450-452.LI C L. Discussion of undercompaction of rocks. Xinjiang Petroleum Geology,2005,26(4):450-452.
[17]刘向君,刘堂晏,刘诗琼.测井原理及工程应用.北京:石油工业出版社,2006:43-46,116-118.LIU X J,LIU T Y,LIU S Q. Principle and engineering application of well logging. Beijing:Petroleum Industry Press,2006:43-46,116-118.
[18]丁次乾.矿场地球物理.东营:石油大学出版社,1992:342-344.DING C Q. Field geophysics. Dongying:Press of University of Petroleum,China,1992:342-344.
[19] ZHANG J C. Effective stress,porosity,velocity and abnormal pore pressure prediction accounting for compaction disequilibrium and unloading. Marine&Petroleum Geology,2013,45(4):2-11.
[20]齐亚林,惠潇,梁艳,等.平衡深度法恢复鄂尔多斯盆地延长组过剩压力探讨岩.石油地质与工程,2014,28(5):20-22.QI Y L,HUI X,LIANG Y,et al.Equilibrium depth method to restore Yanchang formation pressure of Ordos Basin. Petroleum Geology and Engineering,2014,28(5):20-22.