川西前陆盆地上三叠统岩性地层圈闭勘探前景分析
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摘要
岩性地层圈闭是川西前陆盆地下一步油气勘探最重要的领域,对川西前陆盆地上三叠统岩性地层圈闭的特征、类型和发育模式的研究可为岩性地层气藏的勘探提供重要的理论依据。在分析岩性地层圈闭形成的地质基础上,应用层序地层学方法,通过不整合面、地震反射特征、地层叠置样式、岩性和岩相的变化等标志将川西前陆盆地上三叠统划分为4个三级层序和12个体系域。在连井剖面层序对比的基础上建立了川西前陆盆地上三叠统等时地层格架,分析了不同体系域内部砂体的类型和勘探的有利条件,阐述了川西前陆盆地不同区带岩性地层圈闭的特征、发育模式及岩性地层圈闭的勘探潜力和勘探重点。冲断带—前渊带为陡坡冲积扇—扇三角洲沉积模式,有利的岩性圈闭为低位体系域时期的辫状河下切谷和湖侵体系域至高位体系域时期的浊积扇岩性圈闭;斜坡带—隆起带为缓坡三角洲沉积模式,是寻找不整合遮挡、地层超覆尖灭、透镜状砂岩圈闭和砂岩上倾尖灭岩性地层气藏的理想目标区。
Upper Triassic lithologic and stratigraphic traps of in west Sichuanforeland basin is the most important exploration target.The research on character,types,mode of upper Triassic in west Sichuanforeland basin provides an important theoretical basis for the next exploration of lithostratigraphic gas reservoirs.Based on analyzing the geological setting of lithologic and stratigraphic traps,upper Triassic in west Sichuan foreland basin was divided into 4 sequences and 12 system tracts according to sequence boundaries,such as unconformity,seismic reflection characteristics,stacking patterns of stratigraphy,changes of lithology and lithofacies.The matching of successions in well-tie sections made it possible to construct the isochronal stratigraphic framework. The sand bodies types and favorable prospecting conditions in the system tracts and the character,pattern,prospect,exploration priority of lithologic and stratigraphic traps in different belts were researched.Steep slope outfall fan and fan delta sedimentation model were developed in foreland overthrusl and foredeep belts,and the favorable lithologic traps are LST braided river valley and topogenetic and turbidite fan.Gentle slope delta sedimentationmodel were developed in ramp region and uplift zone,which is the favorable target area for LST unconformity traps,stratigraphicoverlap traps,lenticular sandstone traps and sandstone updip pinchout gas reservoirs.
Upper Triassic lithologic and stratigraphic traps of in west Sichuanforeland basin is the most important exploration target.The research on character,types,mode of upper Triassic in west Sichuanforeland basin provides an important theoretical basis for the next exploration of lithostratigraphic gas reservoirs.Based on analyzing the geological setting of lithologic and stratigraphic traps,upper Triassic in west Sichuan foreland basin was divided into 4 sequences and 12 system tracts according to sequence boundaries,such as unconformity,seismic reflection characteristics,stacking patterns of stratigraphy,changes of lithology and lithofacies.The matching of successions in well-tie sections made it possible to construct the isochronal stratigraphic framework. The sand bodies types and favorable prospecting conditions in the system tracts and the character,pattern,prospect,exploration priority of lithologic and stratigraphic traps in different belts were researched.Steep slope outfall fan and fan delta sedimentation model were developed in foreland overthrusl and foredeep belts,and the favorable lithologic traps are LST braided river valley and topogenetic and turbidite fan.Gentle slope delta sedimentationmodel were developed in ramp region and uplift zone,which is the favorable target area for LST unconformity traps,stratigraphicoverlap traps,lenticular sandstone traps and sandstone updip pinchout gas reservoirs.
引文
[1]罗启后,王世谦.四川盆地中西部三叠系重点含气层系天然气富集条件研究[J].天然气工业,1996,16(增刊):40-54.
[2]吴世祥,汪泽成,张林,等.川西前陆盆地勘探思路分析[J].石油与天然气地质,2001,22(3):210-216.
[3]中石油勘探生产分公司.岩性地层油气藏勘探理论与实践[M].北京:石油工业出版社,2005:340-386.
[4]李丕龙,庞雄奇.隐蔽油气藏形成机理与勘探实践[M].北京:石油工业出版社,2004:1-26.
[5]李祥权,崔丽静,陈少平.隐蔽油气藏勘探回顾与展望[J].油气地质与采收率,2005,12(1):30-32.
[6]邱桂强.陆相断陷盆地高精度层序地层研究现状与思路[J].油气地质与采收率,2005,12(3):1-4.
[7]刘树根,罗志立,戴苏兰.川西前陆盆地的“四川运动”及与油气的关系[J].石油与天然气地质,1996,17(4):276-281.
[8]姜在兴,李华启.层序地层学原理及应用[M].北京:石油工业出版社,1996:35-42.
[9]许希辉,刘开时.川西北柘坝场潜伏构造须二上亚段古河道岩性圈闭初探[J].天然气工业,1995,15(3):28-33.
[10]杨凯歌,何志国.初探川西地区岩性圈闭特征[J].天然气勘探与开发,2003,26(2):12-19.
[2]吴世祥,汪泽成,张林,等.川西前陆盆地勘探思路分析[J].石油与天然气地质,2001,22(3):210-216.
[3]中石油勘探生产分公司.岩性地层油气藏勘探理论与实践[M].北京:石油工业出版社,2005:340-386.
[4]李丕龙,庞雄奇.隐蔽油气藏形成机理与勘探实践[M].北京:石油工业出版社,2004:1-26.
[5]李祥权,崔丽静,陈少平.隐蔽油气藏勘探回顾与展望[J].油气地质与采收率,2005,12(1):30-32.
[6]邱桂强.陆相断陷盆地高精度层序地层研究现状与思路[J].油气地质与采收率,2005,12(3):1-4.
[7]刘树根,罗志立,戴苏兰.川西前陆盆地的“四川运动”及与油气的关系[J].石油与天然气地质,1996,17(4):276-281.
[8]姜在兴,李华启.层序地层学原理及应用[M].北京:石油工业出版社,1996:35-42.
[9]许希辉,刘开时.川西北柘坝场潜伏构造须二上亚段古河道岩性圈闭初探[J].天然气工业,1995,15(3):28-33.
[10]杨凯歌,何志国.初探川西地区岩性圈闭特征[J].天然气勘探与开发,2003,26(2):12-19.
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