柴达木盆地第四系岩性气藏成藏条件
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摘要
柴达木盆地三湖地区第四系为弱成岩疏松砂岩地层,近几年围绕构造圈闭的勘探成效不大,岩性气藏将成为该区天然气储量的又一增长点。在层序地层分析基础上,分析了该盆地第四系独特的沉积条件及岩性气藏成藏条件:①盆地周边的构造坡折带是岩性圈闭的有利发育区;②构造背景上的斜坡带是岩性气藏发育区;③深层岩石的弱成岩作用有利于岩性圈闭的形成。根据对三湖地区第四系构造背景、沉积体系展布特征及岩性圈闭发育条件等的综合分析,得出三湖地区七个泉组发育有岩性尖灭带、盆地内沉积低隆起或鼻隆起带、斜坡带及透镜体等类型的岩性圈闭的认识。最后,提出了三湖地区岩性气藏的勘探技术对策:应加强保低频保振幅地震处理与综合解释,高分辨率露头层序的建立,测井资料的精细对比分析等工作。
The Quaternary in Sanhu area of the Qaidam Basin consists of unconsolidated sandstones experienced with weak diagenesis.So exploration of structural traps in the study area has not been successful in recent years.In contrast,lithologic gas reservoirs will be a new source of gas reserve growth.Based on an analysis of sequence stratigraphy,we studied the unique depositional conditions and hydrocarbon accumulation conditions of lithologic gas reservoirs in the Quaternary.The following results were obtained.①The slope break zones in the periphery of the basin are favorable for the development of lithologic traps;②The slope zones have well-developed lithologic gas reservoirs;③The weak diagenesis of the deep rocks is favorable for the formation of lithologic traps.Based on a comprehensive analysis of the structural settings,distribution characteristics of the depositional systems and the conditions of lithologic trap development of the Quaternary in the Sanhu area,we identified several types of lithologic traps in the Qigequan Formation,including lithologic pinch-out zones,low uplift or nose-like uplift zones within the basin,slope zones and lenses.Specific technical proposals for exploration of lithologic gas reservoirs in Sanhu area were presented,including the enhancement of low-frequency-and amplitude-preservation seismic processing and comprehensive interpretation,the establishment of high-resolution outcrop sequences,and the detailed correlation of log data.
The Quaternary in Sanhu area of the Qaidam Basin consists of unconsolidated sandstones experienced with weak diagenesis.So exploration of structural traps in the study area has not been successful in recent years.In contrast,lithologic gas reservoirs will be a new source of gas reserve growth.Based on an analysis of sequence stratigraphy,we studied the unique depositional conditions and hydrocarbon accumulation conditions of lithologic gas reservoirs in the Quaternary.The following results were obtained.①The slope break zones in the periphery of the basin are favorable for the development of lithologic traps;②The slope zones have well-developed lithologic gas reservoirs;③The weak diagenesis of the deep rocks is favorable for the formation of lithologic traps.Based on a comprehensive analysis of the structural settings,distribution characteristics of the depositional systems and the conditions of lithologic trap development of the Quaternary in the Sanhu area,we identified several types of lithologic traps in the Qigequan Formation,including lithologic pinch-out zones,low uplift or nose-like uplift zones within the basin,slope zones and lenses.Specific technical proposals for exploration of lithologic gas reservoirs in Sanhu area were presented,including the enhancement of low-frequency-and amplitude-preservation seismic processing and comprehensive interpretation,the establishment of high-resolution outcrop sequences,and the detailed correlation of log data.
引文
[1]朱筱敏,康安,胡宗全,等.柴达木盆地第四系层序地层特征与油气评价[J].石油勘探与开发,2002,29(1):56-60.
[2]贾承造,赵文智,邹才能,等.岩性地层油气藏勘探研究的两项核心技术[J].石油勘探与开发,2004,31(3):3-9.
[3]何亨华,徐明琳.柴达木盆地构造特征及其演化[J].西北油气勘探,2006,18(2):1-10.
[4]惠荣耀,李本亮,丁安娜,等.柴达木盆地三湖凹陷岩性气藏的勘探前景[J].天然气地球科学,2005,16(4):402-407,15-16.
[2]贾承造,赵文智,邹才能,等.岩性地层油气藏勘探研究的两项核心技术[J].石油勘探与开发,2004,31(3):3-9.
[3]何亨华,徐明琳.柴达木盆地构造特征及其演化[J].西北油气勘探,2006,18(2):1-10.
[4]惠荣耀,李本亮,丁安娜,等.柴达木盆地三湖凹陷岩性气藏的勘探前景[J].天然气地球科学,2005,16(4):402-407,15-16.
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