三湖地区真假含气异常识别和消除技术及应用
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摘要
中国西部的柴达木盆地三湖地区是中国陆上中大型气田,天然气储量丰富,勘探潜力巨大。勘探实践证实,该区存在表层低速带引起的地震剖面异常和地层含气引起的地震异常,并都以"低频、强振幅、同相轴下拉"的特征展现在地震剖面上。该区地表相对比较平坦,以往表层调查工作比较少,难以识别和消除表层低速带引起的地震异常,严重影响该区天然勘探开发进程。这里首先采用共偏移距技术和双域反射时间特征技术较好识别表层结构异常带,其次采用精细表层调查和初至反演表层结构建模来确定表层结构异常带,最后采用高精度模型约束初至折射静校正技术较好消除该区表层低速带引起的地震异常。通过实际资料验证,该方法取得良好应用效果,较好解决该区由于巨厚低降速带引起的地震剖面异常的识别和消除问题,也为类似地区的地震勘探,提供了一个参考。
The Sanhu area,located in the eastern gas field of the Qaidam basin,is a medium-scale land gas field in China,and it is one of the most favorable areas for gas exploration.The reservoir is located in shallow,unconsolidated Quaternary strata,consisting mostly of thin,interbedded sand and shale that have undergone weak diagenesis.Exploration campaigns have recognized anomalies in seismic sections caused by the near-surface low-velocity zones,and by gas-bearing layers.These include lowered velocity,lowered frequency,and pushdown of seismic events.Seismic anomalies caused by the near-surface or by gas-bearing layers are difficult to distinguish due to the shallow target formation.In this paper,we 1)introduce a common offset stack section technique and double-domain reflection feature recognition technique to identify near-surface anomaly zones,2)evaluate our near-surface anomaly recognition techniques and test for accuracy using detailed,near-surface structural surveys from anomaly zones,and 3)adopt a precise refraction static correction technique to remove near-surface anomalies.The methods presented in this study produce good results by using real seismic data,and are also suitable to solve problems associated with near-surface anomaly recognition and removal.These methods can also be useful for seismic prospecting in similarly complex areas.
The Sanhu area,located in the eastern gas field of the Qaidam basin,is a medium-scale land gas field in China,and it is one of the most favorable areas for gas exploration.The reservoir is located in shallow,unconsolidated Quaternary strata,consisting mostly of thin,interbedded sand and shale that have undergone weak diagenesis.Exploration campaigns have recognized anomalies in seismic sections caused by the near-surface low-velocity zones,and by gas-bearing layers.These include lowered velocity,lowered frequency,and pushdown of seismic events.Seismic anomalies caused by the near-surface or by gas-bearing layers are difficult to distinguish due to the shallow target formation.In this paper,we 1)introduce a common offset stack section technique and double-domain reflection feature recognition technique to identify near-surface anomaly zones,2)evaluate our near-surface anomaly recognition techniques and test for accuracy using detailed,near-surface structural surveys from anomaly zones,and 3)adopt a precise refraction static correction technique to remove near-surface anomalies.The methods presented in this study produce good results by using real seismic data,and are also suitable to solve problems associated with near-surface anomaly recognition and removal.These methods can also be useful for seismic prospecting in similarly complex areas.
引文
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[9]王海立,翟俊伟,宁宏晓,等.三湖地区真假含气地震异常的识别与处理技术[J].天然气工业,2011,31(6):39-41.WANG H l,ZHAI J W,NING H X,et al.Identification and elimination of non gas related seismic anomalies in the Sanhu area,Qaidam Basin[J].Natural Gas Industry,2011,31(6):39-41.(In Chinese)
[10]吴永国,李国顺,何永清,等.疏松砂岩区高精度地震采集技术及效果[J].石油地球物理勘探,2013,48(1):8-14.WU Y G,LI G S,HE Y Q,et al.Seismic acquisition technology and effect of high precision of unconsolidated sandstone area[J].Oil Geophysical Prospecting,2013,48(1):8-14.(In Chinese)
[11]王海,赵瑞培,吴明生等.柴北缘地区地震静校正技术研究[J].石油地球物理勘探,2009,44(A01):150-153.WANG H,ZHAO R P,WU M S,et al.Study on the technology of static correction in seismic area of the north margin of the wood[J].Oil Geophysical Prospecting,2009,44(A01):150-153.(In Chinese)
[12]张新立,谢卫民.柴达木盆地折射静校正方法的应用研究[J].石油地球物理勘探,2002,37(B09):52-57.ZHANG X L,XIE W M.Application of static correction method of refraction of Qaidam Basin[J].Oil Geophysical Prospecting,2002,37(B09):52-57.(In Chinese)
[2]张晓宝,徐自远,段毅,等.柴达木盆地三湖地区第四系生物气的形成途径与运聚方式[J].地质论评,2003,49(2):168-174.ZHANG X B,XU Z Y,DUAN Y,et al.The Quaternary biogenic gas in Sanhu area of Qaidam basin formation and migration and accumulation[J].Geological Review,2003,49(2):168-174.(In Chinese)
[3]魏国齐,刘德来,张英,等.柴达木盆地第四系生物气形成机理,分布规律与勘探前景[J].石油勘探与开发,2006,32(4):84-89.WEI G Q,LIU D L,ZHANG Y,et al.The mechanism of formation of distribution and exploration prospect of the Quaternary biogenic gas in Qaidam Basin[J].Petroleum Exploration and Development,2006,32(4):84-89.(In Chinese)
[4]梁全胜,刘震,党玉琪.柴达木盆地三湖地区第四系生物气成因类型的研究[J].中国西部油气地质,2005,1(1):66-69.LIANG Q S,LIU Z,DANG Y Q.Study on genetic types of the Quaternary biogenic gas in Sanhu area of Qaidam Basin[J].West China Petroleum Geosciences,2005,1(1):66-69.(In Chinese)
[5]王西文,陈志勇,冯云发,等.柴达木盆地三湖地区生物天然气储层预测方法[J].石油物探,2007,46(5):471-483.WANG X W,CHEN Z Y,FENG F Y,et al.Method for prediction of biogas in Sanhu area of Qaidam Basin[J].Geophysical Prospecting For Petroleum,2007,46(5):471-483.(In Chinese)
[6]张绍胜,曾富英,孔骅.柴达木盆地三湖地区地震异常分析[J].天然气工业,2007,27(增刊A):176-177.ZHANG S H,ZENG F Y,KONG H.Analysis of abnormal seismic in Sanhu area of Qaidam Basin[J].Natural Gas Industry,2007,27(SUP A):176-177.(In Chinese)
[7]王西文,徐凤银,冯云发,等.三湖地区地震资料处理中的静校正方法研究[J].石油地球物理勘探,2007,42(5):572-580.WANG X W,XU F Y,FENG Y F,et al.Study of static correction methods in seismic data processing in Sanhu area[J].Oil Geophysical Prospecting,2007,42(5):572-580.(In Chinese)
[8]曾富英,张绍胜,孔骅,等.柴达木盆地三湖地区表层低速带引起的地震异常判识及消除[J].石油物探,2012,51(2):156-163.ZENG F Y,ZHANG S S,K H,et al.Seismic surface low velocity zone caused the Sanhu area of Qaidam Basin anomaly identification and elimination of[J].Oil Geophysical Prospecting,2012,51(2):156-163.(In Chinese)
[9]王海立,翟俊伟,宁宏晓,等.三湖地区真假含气地震异常的识别与处理技术[J].天然气工业,2011,31(6):39-41.WANG H l,ZHAI J W,NING H X,et al.Identification and elimination of non gas related seismic anomalies in the Sanhu area,Qaidam Basin[J].Natural Gas Industry,2011,31(6):39-41.(In Chinese)
[10]吴永国,李国顺,何永清,等.疏松砂岩区高精度地震采集技术及效果[J].石油地球物理勘探,2013,48(1):8-14.WU Y G,LI G S,HE Y Q,et al.Seismic acquisition technology and effect of high precision of unconsolidated sandstone area[J].Oil Geophysical Prospecting,2013,48(1):8-14.(In Chinese)
[11]王海,赵瑞培,吴明生等.柴北缘地区地震静校正技术研究[J].石油地球物理勘探,2009,44(A01):150-153.WANG H,ZHAO R P,WU M S,et al.Study on the technology of static correction in seismic area of the north margin of the wood[J].Oil Geophysical Prospecting,2009,44(A01):150-153.(In Chinese)
[12]张新立,谢卫民.柴达木盆地折射静校正方法的应用研究[J].石油地球物理勘探,2002,37(B09):52-57.ZHANG X L,XIE W M.Application of static correction method of refraction of Qaidam Basin[J].Oil Geophysical Prospecting,2002,37(B09):52-57.(In Chinese)