摘要
在琼东南盆地深水中东区勘探新发现了与西区中央峡谷气田特征不同的天然气。目前关于它们的差异及其成因的研究甚少,制约了研究区进一步勘探工作。在油气地球化学特征精细剖析基础上,综合烃源岩沉积环境、孢粉相及地球化学等资料对天然气差异成因进行研究。结果表明,深水区天然气主要为源自下渐新统的煤型气,但不同区天然气重烃碳同位素组成、干燥系数与伴生凝析油甾烷特征及全油碳同位素组成等差别明显。依据差异将深水区煤型气细分为M型与C型2种。前者主要见于中部松南低凸起及东区凹陷边缘,后者见于西区中央峡谷内。两类气差异根源在于二者的烃源岩沉积环境及生气母质的组成不同。除了已形成中央峡谷大型气田C型煤型气外,M型天然气的烃源岩亦具有良好品质和较强的生气潜力,将是深水区天然气勘探的又一重要类型。
A recent discovery of new gas type has been found in the central and eastern deep water of Qiongdongnan Basin,which is proved to be different from the found gases in the western part.The discrepancy and origin discussions are rare and preconditions have been urgent for further exploration.This work exhibits a comprehensive understanding of source rock sedimentation,palynofacies and detailed gas geochemistry to study the formation of natural gas.It is concluded that source rocks in the Lower Oligocene contribute to the natural gas in the deep water,whereas differences are remarkable in the parts of exploration.Chemical and isotopic characteristics of gas and oil have been conducted and two types,Type M and Type C,have been recognized.Gas type M has been usually seen in Songnan Uplift in the central part and the margin of eastern sag.Gas type C is discovered in the western Central Canyon.The main discrepancy of the origin for the gas discovered is the source rock sedimentation environment and the precursor reserved therein.Gas type M has been emerged to be a good gas potential and quality besides the Gas type C found in the central canyon,which will be another important type of natural gas exploration in deep water areas.
引文
[1]Huang Baojia,Wang Zhengfeng,Liang Gang.Natural gas source and migration-accumulation pattern in the central canyon,the deep water area,Qiongdongnan Basin[J].China offshore Oil and Gas,2014,26(5):8-14.黄保家,王振峰,梁刚.琼东南盆地深水区中央峡谷天然气来源及运聚模式[J].中国海上油气,2014,26(5):8-14.
[2]Liang Gang,Gan Jun,Li Xing.Genetic types and origin of natural gas in Lingshui Sag,Qiongdongnan Basin[J].China Offshore Oil and Gas,2015,27(4):47-53.梁刚,甘军,李兴.琼东南盆地陵水凹陷天然气成因类型及来源[J].中国海上油气,2015,27(4):47-53.
[3]Huang Baojia,Tian Hui,Li Xushen,et al.Geochemistry,origin and accumulation of natural gases in the deepwater area of the Qiongdongnan Basin,South China Sea[J].Marine&Petroleum Geology,2016,72:254-267.
[4]Huang Heting,Huang Baojia,Huang Yiwen,et al.Condensate origin and hydrocarbon accumulation mechanism of the deepwater giant gas field in western South China Sea:A case study of Lingshui 17-2Gas Field in Qiongdongnan Basin,South China[J].Petroleum Exploration and Development,2017,44(3):380-388.黄合庭,黄保家,黄义文,等.南海西部深水区大气田凝析油成因与油气成藏机制---以琼东南盆地陵水17-2气田为例[J].石油勘探与开发,2017,44(3):380-388.
[5]Zhang Yingzhao,Xu Xinde,Gan Jun,et al.Study on the geological characteristics,accumulation model and exploration direction of the giant deepwater gas field in the Qiongdongnan Basin[J].Acta Geologica Sinica,2017,91(3):1620-1633.张迎朝,徐新德,甘军,等.琼东南盆地深水大气田地质特征、成藏模式及勘探方向研究[J].地质学报,2017,91(3):1620-1633.
[6]Gan Jun,Zhang Yingzhao,Liang Gang,et al.On accumulation process and dynamic mechanism of natural gas in the deep water area of central canyon,Qiongdongnan Basin[J].Acta Geologica Sinica,2018,92(11):2359-2367.甘军,张迎朝,梁刚,等.琼东南盆地深水区天然气成藏过程及动力机制研究[J].地质学报,2018,92(11):2359-2367.
[7]Zhang Yingzhao,Gan Jun,Yang Xibing,et al.Tectonic evolution and its constraints on the formation of deepwater giant gas field in Lingshui Sag,Qiong Dongnan Basin[J].Marine Geology Frontiers,2017,33(10):22-30.张迎朝,甘军,杨希冰,等.琼东南盆地陵水凹陷构造演化及其对深水大气田形成的控制作用[J].海洋地质前沿,2017,33(10):22-30.
[8]He Jiaxiong,Chen Weihuang,Li Mingxing.Genetic types of natural gas and source rocks in Yingqiong Basin[J].China Offshore Oil and Gas(Geology),2000,14(6):398-405.何家雄,陈伟煌,李明兴.莺-琼盆地天然气成因类型及气源剖析[J].中国海上油气(地质),2000,14(6):398-405.
[9]He Jiaxiong,Li Qiang,Chen Weihuang,et al.Oil/gas mechanism type and gas exploratory direction in Eastsouth Hainan Basin[J].Offshore Oil,2002,22(1):47-56.何家雄,李强,陈伟煌,等.琼东南盆地油气成因类型及近期天然气勘探方向讨论[J].海洋石油,2002,22(1):47-56.
[10]He Jiaxiong,Cheng Shenghong,Yao Yongjian,et al.Main genetic types of oil&gas and characteristics of their accumulation and distribution in north marginal basins,South China sea[J].Natural Gas Geoscience,2008,19(1):34-40.何家雄,陈胜红,姚永坚,等.南海北部边缘盆地油气主要成因类型及运聚分布特征[J].天然气地球科学,2008,19(1):34-40.
[11]Liu Zhenghua,Chen Honghan.Origin mechanism and source rock for natural gas in Qiongdongnan Basin,South China sea[J].Petroleum Geolgogy&Experiment,2011,33(6):639-644.刘正华,陈红汉.琼东南盆地天然气成因类型及其烃源探讨[J].石油实验地质,2011,33(6):639-644.
[12]Xie Yuhong,Li Xushen,Tong Chuanxin,et al.HTHP Gas Accumulation Mechanism and Exploration Practice in Yinggehai Qiongdongnan Basin[M].Beijing:Petroleum Industry Press,2015:15-113.谢玉洪,李绪深,童传新,等.莺-琼盆地高温超压天然气成藏理论与勘探实践[M].北京:石油工业出版社,2015:15-113.
[13]Dai Jinxing.Coal-derived gas theory and its discrimination[J].Chinese Science Bulletin,2018,63(14):1291-1305.戴金星.煤成气及鉴别理论研究进展[J].科学通报,2018,63(14):1291-1305.
[14]Bernard B B,Brooks J M,Sackett W M.Light hydrocarbons in recent Texas continental shelf and slope sediments[J].Journal of Geophysical Research,1978,83(3):4053-4061.
[15]Whiticar M J.A geochemical perspective of natural gas and atmospheric methane[J].Organic Geochemistry,1990,16(1-3):531-547.
[16]Whiticar M J.Carbon and hydrogen isotope systematics of bacterial formation and oxidation of methane[J].Chemical Geology,1999,161:291-314.
[17]Dai Jinxing.Discriminat of kinds of alkane gas[J].Science in China:Series B,1992,22(2):185-193.戴金星.各类烷烃气的鉴别[J].中国科学:B辑,1992,22(2):185-193.
[18]Liu Wenhui,Xu Yongchang.Genetic indicators for natural gases[J].Acta Sedimentologica Sinica,1996,14(1):110-116.刘文汇,徐永昌.天然气成因类型及判识标志[J].沉积学报,1996,14(1):110-116.
[19]Li Jian,Luo Xia,Li Zhisheng,et al.New issue of carbon isotope composition of toluene to be as index of gas-rock correlation[J].Natural Gas Geoscience,2003,14(3):177-180.李剑,罗霞,李志生,等.对甲苯碳同位素值作为气源对比指标的新认识[J].天然气地球科学,2003,14(3):177-180.
[20]Dai Jinxing.Significance of the study on carbon isotopes of alkane gases[J].Natural Gas Industry,2011,31(12):1-6.戴金星.天然气中烷烃气碳同位素研究的意义[J].天然气工业,2011,31(12):1-6.
[21]Burruss R C,Laughrey C D.Carbon and hydrogen isotopic reversals in deep basin gas:Evidence for limits to the stability of hydrocarbons[J].Organic Geochemistry,2010,41(12):1285-1296.
[22]Chung H M,Gormly J R,Squires R M.Origin of gaseous hydrocarbons in subsurface environments:Theoretical considerations of carbon isotope distribution[J].Chemical Geology,1988,77:97-103.
[23]Huang Difan,Xiong Chuanwu,Yang Junjie,et al.Gas source discrimination and natural gas genetic types of central gas field in Ordos Basin[J].Natural Gas Industry,1996,16(6):1-5.黄第藩,熊传武,杨俊杰,等.鄂尔多斯盆地中部气田气源判识和天然气成因类型[J].天然气工业,1996,16(6):1-5.
[24]Huang Difan,Xiong Chuanwu,Yang Junjie,et al.Source rock identification on central big gasfield of Ordos Basin[J].Chinese Science Bulletin,1996,41(17):1588-1592.黄第藩,熊传武,杨俊杰,等.鄂尔多斯盆地中部大气田的气源判识[J].科学通报,1996,41(17):1588-1592.
[25]Guo Xiaoxiao,Xiong Xiaofeng,Xu Xinde,et al.Type classification and origin analysis of natural gas in the Yinggehai Basin[J].Special Oil and Gas Reservoirs,2017,24(5):54-58.郭潇潇,熊小峰,徐新德,等.莺歌海盆地天然气类型划分与来源分析[J].特种油气藏,2017,24(5):54-58.
[26]Rooney M A,Claypool G E,Chung H M.Modeling thermogenic gas generation using carbon isotope ratios of natural gas hydrocarbons[J].Chemical Geology,1995,126(3):219-232.
[27]Xiong Xiaofeng,Xu Xinde,Gan Jun,et al.Differentiated gas distribution,migration and accumulation in the central diaper belt of the Yinggehai Basin[J].Marine Geology Frontiers,2017,33(7):24-31.熊小峰,徐新德,甘军,等.莺歌海盆地中央底辟带天然气差异分布与运聚成藏特征[J].海洋地质前沿,2017,33(7):24-31.
[28]Huang Difan.Distribution characteristics of the carbon isotope in terrestrial organic matter[J].China Offshore Oil and Gas,1993,7(4):1-5.黄第藩.陆相烃源岩有机质的碳同位素分布[J].中国海上油气,1993,7(4):1-5.
[29]Wang Darui.Stable Isotopic Geochemistry of Oil and Gas[M].Beijing:Petroleum Industry Press,2000:246-254.王大锐.油气稳定同位素地球化学[M].北京:石油工业出版社,2000:246-254.
[30]Liu Wenhui,Song Yan,Liu Quanyou,et al.Evolution of carbon isotopic composition in pyrolytic gases generated from coal and its main maccerals[J].Acta Sedimentologica Sinica,2003,21(1):183-190.刘文汇,宋岩,刘全有,等.煤岩及其主显微组份热解气碳同位素组成的演化[J].沉积学报,2003,21(1):183-190.
[31]Chen Jianping,Deng Chunping,Wang Huitong,et al.Genetic potential and geochemical features of pyrolysis oils of macerals from Jurassic coal measures,northwest China[J].Geochimica,2006,35(1):1-5.陈建平,邓春萍,王汇彤,等.中国西北侏罗纪煤系显微组分生烃潜力、产物地球化学特征及其意义[J].地球化学,2006,35(1):1-5.