南海西部涠西南凹陷碳酸盐岩潜山油气成藏条件及勘探潜力
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摘要
南海北部湾盆地涠西南凹陷碳酸盐岩潜山勘探程度低,其油气成藏条件一直不明确。运用有机地球化学、储层综合评价、盆地模拟、缝洞储层识别与预测等技术,对涠西南凹陷碳酸盐岩潜山油气成藏条件进行深入剖析,结果表明:①涠西南凹陷流沙港组二段中深湖相烃源岩发育且分布较广,有机质丰度高、类型好、成熟度适中,是潜山油气的主要来源;②受构造活动、风化淋滤和溶蚀作用等影响,碳酸盐岩潜山溶洞、裂缝、孔隙等储集空间发育;③多期次、多阶段的构造-沉积演化在凹陷内形成多套区域和局部盖层,为潜山油气藏提供了良好的封盖条件;④长期继承性活动断层与骨架砂体、构造脊及不整合面构成了有利油气运移通道。基于上述认识,明确了涠西南凹陷碳酸盐岩潜山具备良好的油气成藏条件,构建了"间接接触单向供烃型"和"直接接触多向供烃型"两种成藏模式,并指出一、二号断裂带发育多个有利目标,估算原油潜在资源量超亿立方米,勘探潜力大,是下步油气拓展勘探的重要新领域。
The exploration degree of carbonate buried hills in the Weixinan sag of Beibuwan basin in the South China Sea is low, and the hydrocarbon accumulation conditions have not been clear. By using organic geochemistry, comprehensive reservoir evaluation, basin simulation, fracture-cave reservoir identification and prediction techniques, the hydrocarbon accumulation conditions of carbonate hills in the Weixinan sag were analyzed, and the results show that: ① the middle-deep lacustrine source rocks of the Second Member of the Liushagang Formation have the wide ranges of development and distribution, high abundance of organic matter, good types and moderate maturity, which are the main sources of oil and gas in buried hills; ② affected by tectonic activities, weathering leaching and dissolution, the carbonate buried hills reservoir spaces of Karst caves, fractures and pores were developed; ③the multi-period and multi-stage tectonic-sedimentary evolutions led to several sets of regional and local caprocks in the sag, which provides good sealing conditions for buried hill reservoirs; ④ the long-term inherited active faults and skeleton sand bodies, tectonic ridges and unconformity surfaces constituted the favorable hydrocarbon migration channels. Based on the above understandings, it is clear that the carbonate buried hills in the Weixinan sag provided good hydrocarbon accumulation conditions, and established two hydrocarbon accumulation modes of "indirect contact unidirectional hydrocarbon supply" and "direct contact multi-directional hydrocarbon supply"; It also points out that the first and second fault zones have developed several favorable targets, the estimated potential resources of crude oil are larger than 100 million cubic meters, and the exploration potential is large, which is an important new field for the exploration expansion of oil and gas in the next step.
The exploration degree of carbonate buried hills in the Weixinan sag of Beibuwan basin in the South China Sea is low, and the hydrocarbon accumulation conditions have not been clear. By using organic geochemistry, comprehensive reservoir evaluation, basin simulation, fracture-cave reservoir identification and prediction techniques, the hydrocarbon accumulation conditions of carbonate hills in the Weixinan sag were analyzed, and the results show that: ① the middle-deep lacustrine source rocks of the Second Member of the Liushagang Formation have the wide ranges of development and distribution, high abundance of organic matter, good types and moderate maturity, which are the main sources of oil and gas in buried hills; ② affected by tectonic activities, weathering leaching and dissolution, the carbonate buried hills reservoir spaces of Karst caves, fractures and pores were developed; ③the multi-period and multi-stage tectonic-sedimentary evolutions led to several sets of regional and local caprocks in the sag, which provides good sealing conditions for buried hill reservoirs; ④ the long-term inherited active faults and skeleton sand bodies, tectonic ridges and unconformity surfaces constituted the favorable hydrocarbon migration channels. Based on the above understandings, it is clear that the carbonate buried hills in the Weixinan sag provided good hydrocarbon accumulation conditions, and established two hydrocarbon accumulation modes of "indirect contact unidirectional hydrocarbon supply" and "direct contact multi-directional hydrocarbon supply"; It also points out that the first and second fault zones have developed several favorable targets, the estimated potential resources of crude oil are larger than 100 million cubic meters, and the exploration potential is large, which is an important new field for the exploration expansion of oil and gas in the next step.
引文
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[11] 黄保家,黄合庭,吴国瑄,等.北部湾盆地始新统湖相富有机质页岩特征及成因机制[J].石油学报,2012,33(1):25-31.HUANG Baojia,HUANG Heting,WU Guoxuan,et al.Geochemical characteristics and formation mechanism of Eocene lacustrine organic-rich shales in the Beibuwan Basin[J].Acta Petrolei Sinica,2012,33(1):25-31.
[12] 张萍,郑军,席敏红,等.北部湾盆地涠西南凹陷西南缘油气成藏条件及模式[J].石油实验地质,2015,37(2):157-163.ZHANG Ping,ZHENG Jun,XI Minhong,et al.Hydrocarbon accumulation conditions and patterns in the southwestern margin of Weixinan Sag,Beibuwan Basin[J].Petroleum Geology & Experiment,2015,37(2):157-163.
[13] 胡忠良.北部湾盆地涠西南凹陷超压系统与油气运移[J].地学前缘,2000,7(3):73-80.HU Zhongliang.Overpressure system and migration of hydrocarbon in Weixinan depression in Beibuwan Basin[J].Earth Science Frontiers,2000,7(3):73-80.
[14] 宋刚练,席敏红,张萍,等.北部湾盆地涠西南凹陷油气成藏特征研究[J].地质与勘探,2012,48(2):415-420.SONG Ganglian,XI Minhong,ZHANG Ping,et al.Hydrocarbon accumulation characteristics in the Weixinan Sag,Beibu Gulf Basin[J].Geology and Exploration,2012,48(2):415-420.
[15] 刘震,谭卓,蔡东升,等.用断层面正压力法分析北部湾盆地涠西南凹陷断层垂向封闭性及其演化[J].地质科学,2008,43(4):695-711.LIU Zhen,TAN Zhuo,CAI Dongsheng,et al.Analysis on fault’s vertical sealing and its evolution by normal pressure of fault surface method in the Weixinan Sag,Beibu Gulf Basin[J].Chinese Journal of Geology,2008,43(4):695-711.
[16] 李春荣,张功成,梁建设,等.北部湾盆地断裂构造特征及其对油气的控制作用[J].石油学报,2012,33(2):195-203.LI Chunrong,ZHANG Gongcheng,LIANG Jianshe,et al.Characteristics of fault structure and its control on hydrocarbons in the Beibuwan Basin[J].Acta Petrolei Sinica,2012,33(2):195-203.
[17] 杨希冰.南海北部北部湾盆地油气藏形成条件[J].中国石油勘探,2016,21(4):85-92.YANG Xibing.Hydrocarbon accumulation conditions in Beibu Gulf Basin,northern South China Sea[J].China Petroleum Exploration,2016,21(4):85-92.
[18] 姜辉.近海断陷湖盆勘探早期沉积特征与成藏条件分析:以北部湾盆地涠西区块为例[D].北京:中国地质大学(北京),2007.JIANG Hui.The analysis on depositional characteristic and play for petroleum and gas in initial stage of exploration in offshore faulted basin:Exemplified by Weixi survey,Beibuwan Basin [D].Beijing: China University of Geosciences ,2007.
[19] 孟卫工,李晓光,刘宝鸿.辽河坳陷变质岩古潜山内幕油藏形成主控因素分析[J].石油天然气地质,2007,28(5):584-588.MENG Weigong,LI Xiaoguang,LIU Baohong.Main factors controlling the formation of interior reservoirs in the metamorphic palaeo-buried hills of the Liaohe Depression[J].Oil & Gas Geology,2007,28(5):584-588.
[20] 叶涛.渤海湾盆地潜山油气藏形成条件及主控因素研究[D].山东青岛:中国石油大学(华东),2013.YE Tao.Studies on formation conditions and main controlling factors of buried hill reservoirs in Bohai Bay Basin[D].Qingdao,Shandong:China University of Petroleum,2013.
[21] 李绪深,甘军,张迎朝,等.南海西部海域断陷湖盆油气聚集规律及勘探前景[J].中国海上油气,2015,27(4):22-29.DOI:10.11935/j.issn.1673-1506.2015.04.003.LI Xushen,GAN Jun,ZHANG Yingzhao,et al.Hydrocarbon accumulation regularity and exploration prospects of fault lacustrine basins in western South China Sea[J].China Offshore Oil and Gas,2015,27(4):22-29.DOI:10.11935/j.issn.1673-1506.2015.04.003.
[2] 徐新德,王碧维,李旭红,等.北部湾盆地涠西南凹陷流沙港组隐蔽油气藏油源及成藏特征[J].天然气地球科学,2012,23(1):92-98.XU Xinde,WANG Biwei,LI Xuhong,et al.Oil sources of concealed reservoirs in Liushagang Formation of the Weixinan sag and accumulation feature,Beibuwan basin[J].Natural Gas Geoscience,2012,23(1):92-98.
[3] 李丕龙,张善文,王永诗,等.断陷盆地多样性潜山成因及成藏研究:以济阳坳陷为例[J].石油学报,2004,25(3):28-31.LI Peilong,ZHANG Shanwen,WANG Yongshi,et al.Multiplex buried hill genesis and pool-forming in rifted basin[J].Acta Petrolei Sinica,2004,25(3):28-31.
[4] CUONG T X,WARREN J R.Bach Ho field,a fractured granitic basement reservoir,Cuu Long Basin,offshore SE Vietnam:A “buried hill” play[J].Petroleum Geology,2009,32(2):129-156.
[5] 邓勇,赵顺兰,陈林,等.北部湾盆地涠西南凹陷灰岩油气藏勘探技术研究[R].广东湛江:南海西部石油研究院,2016.DENG Yong,ZHAO Shunlan,CHEN Lin,et al.Research on exploration technology of buried hills reservoir in Weixinan sag,Beibuwan Basin[R].Zhanjiang,Guangdong:Research Institute of Zhanjiang Branch,CNOOC Ltd.,2016.
[6] 龚再升,李思田,等著.南海北部大陆边缘盆地分析与油气聚集[M].北京:科学出版社,1997:65-74.
[7] 徐永欣.北部湾盆地涠西南凹陷及围区前第三系基岩地质推断及潜山评价[R].广东湛江:南海西部石油研究院,1989.XU Yongxin.Geological inference and evaluation of buried hills in Weixinan Sag,Beibuwan Basin[R].Zhanjiang,Guangdong:Research Institute of Zhanjiang Branch,CNOOC Ltd.,1989.
[8] 孙晓猛,张旭庆,张功成,等.南海北部新生代盆地基底结构及构造属性[J].中国科学:地球科学,2014,44(6):1312-1323.SUN Xiaomeng,ZHANG Xuqing,ZHANG Gongcheng,et al.Texture and tectonic attribute of Cenozoic basin basement in the northern South China Sea[J].Science China:Earth Sciences,2014,57:1199-1211.
[9] 朱伟林,江文荣.北部湾盆地涠西南凹陷断裂与油气藏[J].石油学报,1998,19(3):6-10.ZHU Weilin,JIANG Wenrong.Relations between fractures and hydrocarbon reservoirs in Weixinan Sag[J].Acta Petrolei Sinica,1998,19(3):6-10.
[10] 谢瑞永,黄保家,李旭红,等.北部湾盆地涠西南凹陷流沙港组烃源岩生烃潜力评价[J].地质学刊,2014,38(4):670-675.XIE Ruiyong,HUANG Baojia,LI Xuhong,et al.Hydrocarbon generation potential evaluation of source rocks in Liushagang Formation in Weixinan sag of Beibuwan Basin[J].Journal of Geology,2014,38(4):670-675.
[11] 黄保家,黄合庭,吴国瑄,等.北部湾盆地始新统湖相富有机质页岩特征及成因机制[J].石油学报,2012,33(1):25-31.HUANG Baojia,HUANG Heting,WU Guoxuan,et al.Geochemical characteristics and formation mechanism of Eocene lacustrine organic-rich shales in the Beibuwan Basin[J].Acta Petrolei Sinica,2012,33(1):25-31.
[12] 张萍,郑军,席敏红,等.北部湾盆地涠西南凹陷西南缘油气成藏条件及模式[J].石油实验地质,2015,37(2):157-163.ZHANG Ping,ZHENG Jun,XI Minhong,et al.Hydrocarbon accumulation conditions and patterns in the southwestern margin of Weixinan Sag,Beibuwan Basin[J].Petroleum Geology & Experiment,2015,37(2):157-163.
[13] 胡忠良.北部湾盆地涠西南凹陷超压系统与油气运移[J].地学前缘,2000,7(3):73-80.HU Zhongliang.Overpressure system and migration of hydrocarbon in Weixinan depression in Beibuwan Basin[J].Earth Science Frontiers,2000,7(3):73-80.
[14] 宋刚练,席敏红,张萍,等.北部湾盆地涠西南凹陷油气成藏特征研究[J].地质与勘探,2012,48(2):415-420.SONG Ganglian,XI Minhong,ZHANG Ping,et al.Hydrocarbon accumulation characteristics in the Weixinan Sag,Beibu Gulf Basin[J].Geology and Exploration,2012,48(2):415-420.
[15] 刘震,谭卓,蔡东升,等.用断层面正压力法分析北部湾盆地涠西南凹陷断层垂向封闭性及其演化[J].地质科学,2008,43(4):695-711.LIU Zhen,TAN Zhuo,CAI Dongsheng,et al.Analysis on fault’s vertical sealing and its evolution by normal pressure of fault surface method in the Weixinan Sag,Beibu Gulf Basin[J].Chinese Journal of Geology,2008,43(4):695-711.
[16] 李春荣,张功成,梁建设,等.北部湾盆地断裂构造特征及其对油气的控制作用[J].石油学报,2012,33(2):195-203.LI Chunrong,ZHANG Gongcheng,LIANG Jianshe,et al.Characteristics of fault structure and its control on hydrocarbons in the Beibuwan Basin[J].Acta Petrolei Sinica,2012,33(2):195-203.
[17] 杨希冰.南海北部北部湾盆地油气藏形成条件[J].中国石油勘探,2016,21(4):85-92.YANG Xibing.Hydrocarbon accumulation conditions in Beibu Gulf Basin,northern South China Sea[J].China Petroleum Exploration,2016,21(4):85-92.
[18] 姜辉.近海断陷湖盆勘探早期沉积特征与成藏条件分析:以北部湾盆地涠西区块为例[D].北京:中国地质大学(北京),2007.JIANG Hui.The analysis on depositional characteristic and play for petroleum and gas in initial stage of exploration in offshore faulted basin:Exemplified by Weixi survey,Beibuwan Basin [D].Beijing: China University of Geosciences ,2007.
[19] 孟卫工,李晓光,刘宝鸿.辽河坳陷变质岩古潜山内幕油藏形成主控因素分析[J].石油天然气地质,2007,28(5):584-588.MENG Weigong,LI Xiaoguang,LIU Baohong.Main factors controlling the formation of interior reservoirs in the metamorphic palaeo-buried hills of the Liaohe Depression[J].Oil & Gas Geology,2007,28(5):584-588.
[20] 叶涛.渤海湾盆地潜山油气藏形成条件及主控因素研究[D].山东青岛:中国石油大学(华东),2013.YE Tao.Studies on formation conditions and main controlling factors of buried hill reservoirs in Bohai Bay Basin[D].Qingdao,Shandong:China University of Petroleum,2013.
[21] 李绪深,甘军,张迎朝,等.南海西部海域断陷湖盆油气聚集规律及勘探前景[J].中国海上油气,2015,27(4):22-29.DOI:10.11935/j.issn.1673-1506.2015.04.003.LI Xushen,GAN Jun,ZHANG Yingzhao,et al.Hydrocarbon accumulation regularity and exploration prospects of fault lacustrine basins in western South China Sea[J].China Offshore Oil and Gas,2015,27(4):22-29.DOI:10.11935/j.issn.1673-1506.2015.04.003.