长江三角洲启东地区全新统气源岩有机地球化学特征及生物气形成的控制因素
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摘要
根据钻井岩心、古生物、有机岩石学观察及有机地化测试数据分析,结合区域地质背景资料,对长江三角洲启东地区ZK01井全新统地层中两套气源岩的沉积特征、有机质丰度、有机质类型、有机质成熟度等有机地球化学特征进行了系统研究,探讨控制研究区浅层生物气生成的主要因素。结果表明,全新统河口湾—河漫滩相灰色黏土及粉砂质黏土中有机碳含量在0.20%~0.65%之间,平均0.46%,氯仿沥青"A"平均值71.71×10~(-6);浅海相深灰色淤泥质黏土有机碳含量在0.19%~0.52%之间,平均0.34%,氯仿沥青"A"平均值65.69×10~(-6);前者有机质丰度略高于后者,生气能力略强于后者。两套气源岩中有机质来源均由低等水生生物和陆源高等植物两部分组成,属于混源输入,且以陆源高等植物有机质为主,有机质类型为含草本腐殖型、含草本腐泥腐殖型。两套气源岩镜质体反射率(Ro)在0.50%~0.65%之间,正构烷烃奇偶优势明显,热解最大峰温峰多数低于435℃,表明有机质处于未成熟阶段。长江三角洲启东地区具有有利于浅层生物气生成的基础地质条件、物质条件、地球化学条件,这些因素相互作用,相互制约,相互补充。
Based on a relatively systematic study of core lithology, paleontology, organic petrology and organic geochemistry, combined with regional geological background, the abundance, types and maturity of organic matter in the two sets of gas-generating source rocks of the ZK01 well, Qidong area, Changjiang(Yangtze) River delta, were investigated. Controlling factors for the formation of shallow biogenic gas in this study were further addressed. Results show that TOC value of the estuary-floodplain facies is between 0.20% and 0.65% with an average of 0.46%, and the chloroform bitumen content averages at 71.71×10~(-6). The TOC value of the shallow marine facies is between 0.19% and 0.52% with an average of 0.34%, and the chloroform bitumen content averages at 65.69×10~(-6). Thus, the organic matter abundance of estuary-floodplain facies is higher than that of shallow marine facies. This implies a higher gas productivity for the source rocks in the estuary-floodplain facies floodplain. Terrigenous organisms take dominance in organic matters of the Holocene gas-source sediments, and lower aquatic organisms are also present. The organic matter types are herbaceous sapropel-humic and herbaceous humic. Organic matters are still in immature stage, with the Ro ranging between 0.50% and 0.65%, an odd even predominance of n-alkanes, and Tmax value below 435℃. The formation of the shallow biogenic gas is mainly controlled by three factors, i.e., geological conditions, material conditions and geochemical conditions. The interaction, influence and supplement of these three factors are conducive to generate and accumulate shallow-biogenic gas.
Based on a relatively systematic study of core lithology, paleontology, organic petrology and organic geochemistry, combined with regional geological background, the abundance, types and maturity of organic matter in the two sets of gas-generating source rocks of the ZK01 well, Qidong area, Changjiang(Yangtze) River delta, were investigated. Controlling factors for the formation of shallow biogenic gas in this study were further addressed. Results show that TOC value of the estuary-floodplain facies is between 0.20% and 0.65% with an average of 0.46%, and the chloroform bitumen content averages at 71.71×10~(-6). The TOC value of the shallow marine facies is between 0.19% and 0.52% with an average of 0.34%, and the chloroform bitumen content averages at 65.69×10~(-6). Thus, the organic matter abundance of estuary-floodplain facies is higher than that of shallow marine facies. This implies a higher gas productivity for the source rocks in the estuary-floodplain facies floodplain. Terrigenous organisms take dominance in organic matters of the Holocene gas-source sediments, and lower aquatic organisms are also present. The organic matter types are herbaceous sapropel-humic and herbaceous humic. Organic matters are still in immature stage, with the Ro ranging between 0.50% and 0.65%, an odd even predominance of n-alkanes, and Tmax value below 435℃. The formation of the shallow biogenic gas is mainly controlled by three factors, i.e., geological conditions, material conditions and geochemical conditions. The interaction, influence and supplement of these three factors are conducive to generate and accumulate shallow-biogenic gas.
引文
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惠荣耀,李剑,张英,等.2009.生物气源岩评价方法[J].天然气工业,29(2):18-22.
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马宝林,彭作林,史基安,等.2000.天然气形成的地质基础条件[M].北京:科学出版社.
梅建森,康毅力,张永高,等.2007.柴达木盆地生物气源岩评价及勘探方向[J].天然气工业,27(9):17-20.
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吴绪旭,王张华,何中发.2012.总硫总有机碳比(TS/TOC)对长江三角洲南部平原沉积环境的指示意义[J].古地理学报,14(6):821-828.
张水昌,赵文智,李先奇,等.2005.生物气研究新进展与勘探策略[J].石油勘探与开发,32(4):90-96.
张文昭,程永才.1995.浙江省第四系浅层天然气勘探新进展[J].天然气工业,15(1):6-9.
张英,李剑,张奎,等.2007.柴达木盆地三湖地区第四系生物气源岩中可溶有机质丰度及地质意义[J].地质学报,81(12):1716-1722.
郑开富.1998.江苏地区第四系浅层天然气的分布与勘探前景[J].天然气工业,18(3):20-24.
周翥虹,周瑞年,管志强.1994.柴达木盆地东部第四系气源岩地化特征与生物气前景[J].石油勘探与开发,21(2):30-36.
朱永其,曾成开,金长茂.1981.东海大陆架晚更新世以来海面变化[J].科学通报,26(19):1195-1198.
Lin C M,Gu L X,Li G Y,et al.2004.Geology and formation mechanism of late Quaternary shallow biogenic gas reservoirs in the Hangzhou Bay area,eastern China[J].AAPG Bulletin,88(5):613-625.
Lin C M,Li Y L,Zhuo H C,et al.2010.Features and sealing mechanism of shallow biogenic gas in incised valley fills(the Qiantang River,eastern China):A case study[J].Marine and Petroleum Geology,27(4):909-922.
Ni Y Y,Dai J X,Zou C N,et al.2013.Geochemical characteristics of biogenic gases in China[J].International Journal of Coal Geology,113(4):76-87.
Orange D,García-García A,Lorenson T,et al.2005.Shallow gas and flood deposition on the Po Delta[J].Marine Geology,s222-223:159-177.
Rice D D and Claypool G E.1981.Geoeration,accumulation,and resource potential of biogenic gas[J].AAPG Bulletin,65(1):5-25.
Schoell M.1983.Genetic characterization of natural gas[J].AAPG Bull,67(12):2225-2238.
Shen P and Xu Y C.1993.Isotopic compositional characteristics of terrigenous natural gases in China[J].Chinese Journal of Geochemistry,12(1):14-24.
Shen P,Wang X F,Xu Y,et al.2009.Carbon and hydrogen isotopic composition and generation pathway of biogenic gas in China[J].Chinese Journal of Geochemistry,28(2):119-124.
Shuai Y H,Zhang S C,Ma D,et al.2015.Quaternary biogenic gases in the Qaidam Basin,Western China[J].Bulletin of Canadian Petroleum Geology,63(1):75-83.
Whiticar M J,Faber E and Schoell M.1986.Biogenic methane formation in marine and freshwater environments:CO2 reduction vs.acetate fermentation-Isotope evidence[J].Geochimica et Cosmochimica Acta,50:693-709.
Whiticar M J.1999.Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane[J].Chemical Geology,161(s1-3):291-314.
Zhang S C,Huang H P,Su J,et al.2013.Geochemistry of Paleozoic marine oils from the Tarim Basin,NW China.Part 4:Paleobiodegradation and oil charge mixing[J].Organic Geochemistry,67(1):41-57.
邓程文,张霞,林春明,等.2016.长江河口区末次冰期以来沉积物的粒度特征及水动力条件[J].海洋地质与第四纪地质,36(6):185-198.
郭泽清,李本亮,曾富英,等.2006.生物气分布特征和成藏条件[J].天然气地球科学,17(3):407-413.
胡惠民,黄立人,杨国华.1992.长江三角洲及其邻近地区的现代地壳垂直运动[J].地理学报,47(1):22-30.
惠荣耀,李剑,张英,等.2009.生物气源岩评价方法[J].天然气工业,29(2):18-22.
康晏,王万春,任军虎.2004.生物气生成的地球化学因素分析[J].矿物岩石地球化学通报,23(4):350-354.
李从先,汪品先.1998.长江晚第四纪河口地层学研究[M].北京:科学出版社.
李从先,张桂甲.1996.晚第四纪长江和钱塘江河口三角洲地区的层序界面和沉积间断[J].自然科学进展,6(4):461-469.
李先奇,张水昌,朱光有,等.2005.中国生物成因气的类型划分与研究方向[J].天然气地球科学,16(4):477-483.
林春明,黄志诚,朱嗣昭,等.1999.杭州湾沿岸平原晚第四纪沉积特征和沉积过程[J].地质学报,73(2):120-130.
林春明,李艳丽,漆滨汶.2006.生物气研究现状与勘探前景[J].古地理学报,8(3):327-340.
林春明,张霞,徐振宇,等.2015.长江三角洲晚第四纪地层沉积特征与生物气成藏条件分析[J].地球科学进展,30(5):589-601.
刘建,徐莹,赵智鹏,等.2015.生物气源岩评价指标体系研究[J].海洋地质前沿,31(1):16-23.
马宝林,彭作林,史基安,等.2000.天然气形成的地质基础条件[M].北京:科学出版社.
梅建森,康毅力,张永高,等.2007.柴达木盆地生物气源岩评价及勘探方向[J].天然气工业,27(9):17-20.
穆亚蓬,王万春,宋振响.2008.生物气源岩评价指标研究现状及展望[J].天然气地球化学,19(6):775-779.
帅燕华,张水昌,陈建平,等.2010.深部生物圈层微生物营养底物来源机制及生物气源岩特征分析[J].中国科学(D辑),地球科学,40(7):866-872.
王国庆,石学法,李从先.2006.长江三角洲晚第四纪沉积地质学研究述评[J].海洋地质与第四纪地质,26(6):131-137.
王明义.1982.长江三角洲浅层天然气[J].天然气工业,2(3):3-9.
吴绪旭,王张华,何中发.2012.总硫总有机碳比(TS/TOC)对长江三角洲南部平原沉积环境的指示意义[J].古地理学报,14(6):821-828.
张水昌,赵文智,李先奇,等.2005.生物气研究新进展与勘探策略[J].石油勘探与开发,32(4):90-96.
张文昭,程永才.1995.浙江省第四系浅层天然气勘探新进展[J].天然气工业,15(1):6-9.
张英,李剑,张奎,等.2007.柴达木盆地三湖地区第四系生物气源岩中可溶有机质丰度及地质意义[J].地质学报,81(12):1716-1722.
郑开富.1998.江苏地区第四系浅层天然气的分布与勘探前景[J].天然气工业,18(3):20-24.
周翥虹,周瑞年,管志强.1994.柴达木盆地东部第四系气源岩地化特征与生物气前景[J].石油勘探与开发,21(2):30-36.
朱永其,曾成开,金长茂.1981.东海大陆架晚更新世以来海面变化[J].科学通报,26(19):1195-1198.
Lin C M,Gu L X,Li G Y,et al.2004.Geology and formation mechanism of late Quaternary shallow biogenic gas reservoirs in the Hangzhou Bay area,eastern China[J].AAPG Bulletin,88(5):613-625.
Lin C M,Li Y L,Zhuo H C,et al.2010.Features and sealing mechanism of shallow biogenic gas in incised valley fills(the Qiantang River,eastern China):A case study[J].Marine and Petroleum Geology,27(4):909-922.
Ni Y Y,Dai J X,Zou C N,et al.2013.Geochemical characteristics of biogenic gases in China[J].International Journal of Coal Geology,113(4):76-87.
Orange D,García-García A,Lorenson T,et al.2005.Shallow gas and flood deposition on the Po Delta[J].Marine Geology,s222-223:159-177.
Rice D D and Claypool G E.1981.Geoeration,accumulation,and resource potential of biogenic gas[J].AAPG Bulletin,65(1):5-25.
Schoell M.1983.Genetic characterization of natural gas[J].AAPG Bull,67(12):2225-2238.
Shen P and Xu Y C.1993.Isotopic compositional characteristics of terrigenous natural gases in China[J].Chinese Journal of Geochemistry,12(1):14-24.
Shen P,Wang X F,Xu Y,et al.2009.Carbon and hydrogen isotopic composition and generation pathway of biogenic gas in China[J].Chinese Journal of Geochemistry,28(2):119-124.
Shuai Y H,Zhang S C,Ma D,et al.2015.Quaternary biogenic gases in the Qaidam Basin,Western China[J].Bulletin of Canadian Petroleum Geology,63(1):75-83.
Whiticar M J,Faber E and Schoell M.1986.Biogenic methane formation in marine and freshwater environments:CO2 reduction vs.acetate fermentation-Isotope evidence[J].Geochimica et Cosmochimica Acta,50:693-709.
Whiticar M J.1999.Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane[J].Chemical Geology,161(s1-3):291-314.
Zhang S C,Huang H P,Su J,et al.2013.Geochemistry of Paleozoic marine oils from the Tarim Basin,NW China.Part 4:Paleobiodegradation and oil charge mixing[J].Organic Geochemistry,67(1):41-57.