AVO反演在南海北部潮汕坳陷中生界地层物性研究中的应用
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摘要
潮汕坳陷是中生界地层为主的沉积坳陷,是南海油气勘探突破的重要领域.LF35-1-1钻井证实了潮汕坳陷存在大套中生代海相地层,但未获油气发现,在钻至目标层前钻遇了侵入岩体,凸显了中生界钻前预测的重要性.本文对收集到的一条穿越潮汕坳陷长排列地震测线资料进行了多次波压制和AVO反演处理,获得了清晰的剖面反射特征,识别了两个中生界AVO异常带.研究区中生代速度普遍较高,但折射波速度计算表明这两个异常带中生界纵波速度低于背景速度,可能具有有利储集物性条件,因此作为AVO分析的选择区.但是AVO反演的纵波速度反射率剖面上显示为很大的数值,因此异常带成岩程度较高,可能不是油气成因的异常.地震偏移剖面也显示异常区受到切穿海底的高角度断裂影响,下部反射模糊杂乱,可能还有岩体侵入的影响,都不利于油气储集.
Located in the northern South China Sea,Chaoshan Depression is an important area for gas and oil exploration as a relict Mesozoic basin.Well LF35-1-1 is the only one so far drilled in northern Chaoshan Depression,which has drilled thick Mesozoic marine deposits,but without any oil show.It has drilled intruded granite before the predicted reservoir.The case further necessitates the pre-drill reservoir analysis.The Mesozoic strata here feature too high velocity as excellent reservoir rocks.Extensive multiple suppression and AVO inversion are done on a new available seismic survey line run through the northwest of Chaoshan Depression.The seismic line is of 6 km long streamer and full of refraction phases from the top of Mesozoic strata.Two zones where the refraction velocities of the top Mesozoic strata are lower than neighboring areas and remarkable AVO anomaly shows are chosen for AVO analysis.However,various AVO attributes over the zones,e.g.,P-wave reflectivity,Poisson's ratio and AVO cross plot,show as large positive values,possibly due to high lithification,not hydrocarbon infill.Further,from the migrated profiles,the zones are found with dense high-angle faults cut through from deep to seabed,weak and chaotic reflection pattern in deep which might be magmatic intrusion.Thus,the analyzed features are unfavorable to reservoir over the worked seismic line.
Located in the northern South China Sea,Chaoshan Depression is an important area for gas and oil exploration as a relict Mesozoic basin.Well LF35-1-1 is the only one so far drilled in northern Chaoshan Depression,which has drilled thick Mesozoic marine deposits,but without any oil show.It has drilled intruded granite before the predicted reservoir.The case further necessitates the pre-drill reservoir analysis.The Mesozoic strata here feature too high velocity as excellent reservoir rocks.Extensive multiple suppression and AVO inversion are done on a new available seismic survey line run through the northwest of Chaoshan Depression.The seismic line is of 6 km long streamer and full of refraction phases from the top of Mesozoic strata.Two zones where the refraction velocities of the top Mesozoic strata are lower than neighboring areas and remarkable AVO anomaly shows are chosen for AVO analysis.However,various AVO attributes over the zones,e.g.,P-wave reflectivity,Poisson's ratio and AVO cross plot,show as large positive values,possibly due to high lithification,not hydrocarbon infill.Further,from the migrated profiles,the zones are found with dense high-angle faults cut through from deep to seabed,weak and chaotic reflection pattern in deep which might be magmatic intrusion.Thus,the analyzed features are unfavorable to reservoir over the worked seismic line.
引文
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[7]吴国瑄,王汝建,郝沪军等.南海北部海相中生界发育的微体化石证据.海洋地质与第四纪地质,2007,27(1):79-85.Wu G X,Wang R J,Hao H J,et al.Microfossil evidence fordevelopment of marine mesozoic in the North of South ChinaSea.Marine Geology and Quaternary Geology(in Chinese),2007,27(1):79-85.
[8]邵磊,尤洪庆,郝沪军等.南海东北部中生界岩石学特征及沉积环境.地质评论,2007,53(2):164-169.Shao L,You H Q,Hao H J,et al.Petrology and depositionalenvironments of Mesozoic strata in the northeastern SouthChina Sea.Geological Review(in Chinese),2007,53(2):164-169.
[9]郝沪军,施和生,张向涛等.潮汕坳陷中生界及其石油地质条件——基于LF35-1-1探索井钻探结果的讨论.中国海上油气,2009,21(3):151-156.Hao H J,Shi H S,Zhang X T,et al.Mesozoic sediments andtheir petroleum geology conditions in Chaoshan sag:adiscussion based on drilling results from the exploratory wellLF35-1-1.China Offshore Oil and Gas(in Chinese),2009,21(3):151-156.
[10]段九春,米慧芬.潮汕坳陷中生界地震相与沉积相研究.资源与产业,2012,14(1):100-105.Duan J C,Mi H F.Seismic facies and sedimentary facies studyof mesozoic in Chaoshan SAG.Resources and Industries(inChinese),2012,14(1):100-105.
[11]吕修亚,阎贫,陈洁等.折射方法在南海北部潮汕坳陷中生界地层研究中的应用.热带海洋学报,2009,28(1):43-47.LüX Y,Yan P,Chen J,et al.Application of refractionvelocity in studying Mesozoic strata in Chaoshan Depressionon northern margin of South China Sea.Journal of TropicalOceanography(in Chinese),2009,28(1):43-47.
[12]阮爱国,牛雄伟,吴振利等.潮汕坳陷中生代沉积的折射波2D速度结构和密度.高校地质学报,2009,15(4):522-528.Ruan A G,Niu X W,Wu Z L,et al.The 2Dvelocity anddensity structure of the Mesozoic sediments in the Chaoshandepression.Geological Journal of China Universities(inChinese),2009,15(4):522-528.
[13]林秋金,阎贫,于宏等.潮汕坳陷多次波组合压制技术研究.热带海洋学报,2012,31(1):55-61.Lin Q J,Yan P,Yu H,et al.Multiples suppression usingcombination method in Chaoshan Depression of the SouthChina Sea.Journal of Tropical Oceanography(in Chinese),2012,31(1):55-61.
[14]Aki K,Richards P G.Quantitative Seismology:Theoryand Methods.Version 1.Freeman:W.H.Freeman and Co,1980:100-170.
[15]Shuey R T.A simplification of the Zoeppritz equations.Geophysics,1985,50(4):609-614.
[16]Castagna J P,Swan H W,Foster D J.Framework for AVOgradient and intercept interpretation.Geophysics,1998,63(3):948-956.
[17]Young R A,LoPiccolo R D.A comprehensive A VOclassification.The Leading Edge,2003,22(10):1030-1037.
[2]郝沪军,林鹤鸣,杨梦雄等.潮汕坳陷中生界——油气勘探的新领域.中国海上油气(地质),2001,15(3):157-162.Hao H J,Lin H M,Yang M X,et al.The mesozoic in Chaoshandepression:a new domain of petroleum exploration.ChinaOffshore Oil and Gas(Geology)(in Chinese),2001,15(3):157-162.
[3]苏乃容,曾麟,李平鲁.珠江口盆地东部中生代凹陷地质特征.中国海上油气(地质),1995,9(4):228-236.Su N R,Zeng L,Li P L.Geological features of mesozoic sags inthe Eastern part of pearl River Mouth Basin.China OffshoreOil and Gas(Geology)(in Chinese),1995,9(4):228-236.
[4]郝沪军,汪瑞良,张向涛等.珠江口盆地东部海相中生界识别及分布.中国海上油气,2004,16(2):84-88.Hao H J,Wang R L,Zhang X T,et al.Mesozoic marinesediment identification and distribution in the eastern PearlRiver Mouth basin.China Offshore Oil and Gas(in Chinese),2004,16(2):84-88.
[5]赖万忠.中国海域中生界油气勘探.中国海上油气(地质),2001,15(5):311-316.Lai W Z.Petrolweum exploration of mesozoic offshore China.China Offshore Oil and Gas(Geology)(in Chinese),2001,15(5):311-316.
[6]杨树春,仝志刚,贺清等.潮汕坳陷中生界生烃历史及火成岩侵入影响分析——以LF35-1-1井为例.中国海上油气,2008,20(3):152-156.Yang S C,Tong Z G,He Q,et al.Mesozoic hydrocarbongeneration history and igneous intrusion impacts in Chaoshandepression,South China sea:a case of LF35-1-1 well.ChinaOffshore Oil and Gas(in Chinese),2008,20(3):152-156.
[7]吴国瑄,王汝建,郝沪军等.南海北部海相中生界发育的微体化石证据.海洋地质与第四纪地质,2007,27(1):79-85.Wu G X,Wang R J,Hao H J,et al.Microfossil evidence fordevelopment of marine mesozoic in the North of South ChinaSea.Marine Geology and Quaternary Geology(in Chinese),2007,27(1):79-85.
[8]邵磊,尤洪庆,郝沪军等.南海东北部中生界岩石学特征及沉积环境.地质评论,2007,53(2):164-169.Shao L,You H Q,Hao H J,et al.Petrology and depositionalenvironments of Mesozoic strata in the northeastern SouthChina Sea.Geological Review(in Chinese),2007,53(2):164-169.
[9]郝沪军,施和生,张向涛等.潮汕坳陷中生界及其石油地质条件——基于LF35-1-1探索井钻探结果的讨论.中国海上油气,2009,21(3):151-156.Hao H J,Shi H S,Zhang X T,et al.Mesozoic sediments andtheir petroleum geology conditions in Chaoshan sag:adiscussion based on drilling results from the exploratory wellLF35-1-1.China Offshore Oil and Gas(in Chinese),2009,21(3):151-156.
[10]段九春,米慧芬.潮汕坳陷中生界地震相与沉积相研究.资源与产业,2012,14(1):100-105.Duan J C,Mi H F.Seismic facies and sedimentary facies studyof mesozoic in Chaoshan SAG.Resources and Industries(inChinese),2012,14(1):100-105.
[11]吕修亚,阎贫,陈洁等.折射方法在南海北部潮汕坳陷中生界地层研究中的应用.热带海洋学报,2009,28(1):43-47.LüX Y,Yan P,Chen J,et al.Application of refractionvelocity in studying Mesozoic strata in Chaoshan Depressionon northern margin of South China Sea.Journal of TropicalOceanography(in Chinese),2009,28(1):43-47.
[12]阮爱国,牛雄伟,吴振利等.潮汕坳陷中生代沉积的折射波2D速度结构和密度.高校地质学报,2009,15(4):522-528.Ruan A G,Niu X W,Wu Z L,et al.The 2Dvelocity anddensity structure of the Mesozoic sediments in the Chaoshandepression.Geological Journal of China Universities(inChinese),2009,15(4):522-528.
[13]林秋金,阎贫,于宏等.潮汕坳陷多次波组合压制技术研究.热带海洋学报,2012,31(1):55-61.Lin Q J,Yan P,Yu H,et al.Multiples suppression usingcombination method in Chaoshan Depression of the SouthChina Sea.Journal of Tropical Oceanography(in Chinese),2012,31(1):55-61.
[14]Aki K,Richards P G.Quantitative Seismology:Theoryand Methods.Version 1.Freeman:W.H.Freeman and Co,1980:100-170.
[15]Shuey R T.A simplification of the Zoeppritz equations.Geophysics,1985,50(4):609-614.
[16]Castagna J P,Swan H W,Foster D J.Framework for AVOgradient and intercept interpretation.Geophysics,1998,63(3):948-956.
[17]Young R A,LoPiccolo R D.A comprehensive A VOclassification.The Leading Edge,2003,22(10):1030-1037.
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