川西坳陷深层叠复连续型致密砂岩气藏成因及形成过程
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摘要
川西坳陷深层上三叠统须家河组发育典型的致密砂岩气藏,由于该气藏多期构造演化、多期生排烃过程、多期成藏及储层致密化过程复杂的特点,其成因类型和成因机制经过多年的勘探和研究仍然存在争议。文章在剖析典型气藏的基础上,结合研究区构造演化、烃源岩生排烃史和储层致密化过程的研究,综合判识了致密气藏的成因类型,并分析其成因机制。研究结果表明:川西坳陷深层须家河组致密砂岩气藏具有"叠复连续资源潜力大、构造高点低点富气共存、高孔低孔储层含气共存、高压低压气层共存、气水分布复杂"的地质特征。目前气藏的成因类型为"后成"型致密气藏与"先成"型致密气藏的叠加复合型,属叠复连续型致密气藏。川西坳陷深层须家河组演化过程中存在浮力成藏下限和成藏底限,致密砂岩气藏形成和演化受控于2个界限控制下的3个流体动力场的分布和演化。叠复连续型致密砂岩气藏成藏过程可划分为4个阶段:1三叠纪沉积初至三叠纪末,初期天然气成藏条件准备阶段;2三叠纪末至中侏罗世末,早期常规气藏形成阶段;3中侏罗世末至晚侏罗世末,"先成"型致密气藏与"后成"型致密气藏形成阶段;4早白垩世至今,叠复连续型致密油气藏形成及改造阶段。
Typical tight sandstone reservoir are well developed in the deep Triassic Xujiahe Formation inwestern Sichuan depression. It experienced multi-stages of tectonic evolution, hydrocarbon generation and expulsion and reservoir formation,and also experienced complicated processes of reservoir densification,thus,its genetic types and formation mechanisms of gas reservoir are difficult to be recognized. The genetic types and its formation mechanisms have been discussed,through dissecting the typical gas reservoir,combining the tectonic evolution,history of hydrocarbon generation and expulsion and the process of sandstone reservoir densification. The comprehensive study determined the genetic type of tight sandstone reservoir and analyzed its formation mechanism. The results show that the tight sandstone reservoir in deep Triassic Xujiahe Formation in the western Sichuan depression has complex geological characteristics. It characterizes as both high structural and low structural enriched with gas,coexistence of high porosity and low porosity reservoir,coexistence of high pressure and low pressure reservoir,complicated gas-water distribution etc. The present gas reservoir is the recombination and superimposition of two types of reservoirs: pre-existing tight sand gas reservoir and subsequent ones. There are two limits to identify the formation of tight gases,the lower limit of buoyancy-controlled accumulation and the lower limit of hydrocarbon accumulation during the evolution of deep Xujiahe Formation.These two lower limits can divide the hydrocarbon-bearing basin into three kinds of fluid dynamic fields and control the formation and distribution of tight sandstone reservoir. Based on the history of hydrocarbon generation and expulsion,reservoir densification history,reservoir formation and the evolution of structures,the genetic model of the formation and distribution of superimposed continuous hydrocarbon reservoirs has been established,which can be divided into four stages.(1) From the Early Triassic to the end of Triassic,a stage of gas accumulation preparation;(2)From the end of the Late Triassic to the Middle Jurassic,an early stage of formation of conventional gas reservoir;(3)From the end of the Middle Jurassic to the end of Jurassic,a stage of formation of subsequent tight sand gas reservoir and pre-existing tight sand gas reservoir;(4) From the end of the Late Jurassic to the Middle Cretaceous,a stage of formation of superimposed continuous gas reservoir.
Typical tight sandstone reservoir are well developed in the deep Triassic Xujiahe Formation inwestern Sichuan depression. It experienced multi-stages of tectonic evolution, hydrocarbon generation and expulsion and reservoir formation,and also experienced complicated processes of reservoir densification,thus,its genetic types and formation mechanisms of gas reservoir are difficult to be recognized. The genetic types and its formation mechanisms have been discussed,through dissecting the typical gas reservoir,combining the tectonic evolution,history of hydrocarbon generation and expulsion and the process of sandstone reservoir densification. The comprehensive study determined the genetic type of tight sandstone reservoir and analyzed its formation mechanism. The results show that the tight sandstone reservoir in deep Triassic Xujiahe Formation in the western Sichuan depression has complex geological characteristics. It characterizes as both high structural and low structural enriched with gas,coexistence of high porosity and low porosity reservoir,coexistence of high pressure and low pressure reservoir,complicated gas-water distribution etc. The present gas reservoir is the recombination and superimposition of two types of reservoirs: pre-existing tight sand gas reservoir and subsequent ones. There are two limits to identify the formation of tight gases,the lower limit of buoyancy-controlled accumulation and the lower limit of hydrocarbon accumulation during the evolution of deep Xujiahe Formation.These two lower limits can divide the hydrocarbon-bearing basin into three kinds of fluid dynamic fields and control the formation and distribution of tight sandstone reservoir. Based on the history of hydrocarbon generation and expulsion,reservoir densification history,reservoir formation and the evolution of structures,the genetic model of the formation and distribution of superimposed continuous hydrocarbon reservoirs has been established,which can be divided into four stages.(1) From the Early Triassic to the end of Triassic,a stage of gas accumulation preparation;(2)From the end of the Late Triassic to the Middle Jurassic,an early stage of formation of conventional gas reservoir;(3)From the end of the Middle Jurassic to the end of Jurassic,a stage of formation of subsequent tight sand gas reservoir and pre-existing tight sand gas reservoir;(4) From the end of the Late Jurassic to the Middle Cretaceous,a stage of formation of superimposed continuous gas reservoir.
引文
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[15]庞雄奇,黄捍东,林畅松,等.哈萨克斯坦Marsel探区叠复连续气田形成、分布与探测及资源储量评价[J].石油学报,2014,35(6):1012-1056.Pang Xiongqi,Huang Handong,Lin Changsong,et al.Formation,Distribution,Exploration,and Resource Reserve Assessment of Superimposed Continuous Gas Field in Marsel Exploration Area,Kazakhstan[J].Acta Petrolei Sinica,2014,35(6):1012-1056.
[16]陈冬霞,庞雄奇,李林涛,等.川西坳陷中段上三叠统须二段气水分布特征及成因机理[J].现代地质,2010,24(6):1117-1125.Chen Dongxia,Pang Xiongqi,Li Lintao,et al.GasWater Distribution Characteristics and Genetic Mechanism of the Second Sector of the Upper Triassic Xujiahe Formation in the Middle of the Western Sichuan Depression[J].Geoscience,2010,24(6):1117-1125.
[17]姜振学,林世国,庞雄奇,等.两种类型致密砂岩气藏对比[J].石油实验地质,2006,28(3):210-214.Jiang Zhenxue,Lin Shiguo,Pang Xiongqi,et al.The Comparison of Two Types of Tight Sand Gas Reservoir[J].Petroleum Geology&Experiment,2006,28(3):210-214.
[2]罗启厚,王世谦.川中川西地区上三叠统天然气富集条件与分布规律研究[M].北京:石油工业出版社,1997:66-77.Luo Qihou,Wang Shiqian.Gas Accumulation Conditions and Distribution of the Upper Triassic in the Middle and Western of Sichuan Basin[M].Beijing:Petroleum Industry Press,1997:66-77.
[3]王金琪.早聚晚藏:川西坳陷天然气基本特征[J].天然气工业,2001,21(1):4-12.Wang Jinqi.Early Accumulation and Late Seal:The Basic Character of Reservoirs in West Sichuan Depression[J].Natural Gas Industry,2001,21(1):4-12.
[4]宋岩,洪峰.四川盆地川西坳陷深盆气地质条件[J].石油勘探与开发,2001,28(2):11-14.Song Yan,Hong Feng.The Geological Conditions of Deep-Basin Gas in Western Depression of Sichuan Basin[J].Petroleum Exploration and Development,2001,28(2):11-14.
[5]张金亮,常象春,王世谦.四川盆地上三叠统深盆气藏研究[J].石油学报,2002,23(5):27-33.Zhang Jinliang,Chang Xiangchun,Wang Shiqian.Gas Trap Deep-Basin of the Upper Triassic in Sichuan Basin[J].Acta Petrolei Sinica,2002,23(5):27-33.
[6]叶军.再议四川盆地西部坳陷深盆气[J].石油实验地质,2008,30(2):109-114.Ye Jun.Reconsideration of Deep Basin Gas in the Western Sichuan Basin Depression of the Sichuan Basin[J].Petroleum Geology&Experiment,2008,30(2):109-114.
[7]陈昭国.四川盆地川西坳陷深盆气探讨[J].石油实验地质,2005,27(1):33-38.Chen Zhaoguo.Study on Deep Basin in the Western Sichuan Depression,Sichuan Basin[J].Petroleum Geology&Experiment,2005,27(1):33-38.
[8]杨克明,朱宏权.川西叠覆型致密砂岩气区地质特征[J].石油实验地质,2013,35(1):1-8.Yang Keming,Zhu Hongquan.Geological Characterisitics of Superposed Tight Sandstone Gas-Bearing Areas in Western Sichuan[J].Petroleum Geology&Experiment,2013,35(1):1-8.
[9]陈冬霞,李林涛,邓克,等.川西坳陷烃源岩排烃特征与排烃史[J].天然气工业,2010,30(5):41-45.Chen Dongxia,Li Lintao,Deng Ke,et al.Characteristics and History of Hydrocarbon Expulsion of the Upper Tertiary Source Rocks in Western Sichuan Depression[J].Natural Gas Industry,2010,30(5):41-45.
[10]陈冬霞,庞雄奇,杨克明,等.川西坳陷中段上三叠统须二段致密砂岩孔隙度演化史[J].吉林大学学报(地球科学版),2012,42(1):43-50.Chen Dongxia,Pang Xiongqi,Yang Keming,et al.Porosity Evolution of Tight Gas Sand of Second Member of Xujiahe Formation of Upper Triassic,Western Sichuan Depression[J].Journal of Jilin University(Earth Science Edition),2012,42(1):43-50.
[11]Schmoker J W,Fouch T D,Charpentier R R.Gas in the Uinta Basin,Utah:Resources in Continuous Accumulations[J].The Mountain Geologist,1996,33(4):95-104.
[12]Schenk C J.Geologic Definition and Resource Assessment of Continuous(Unconventional)Gas Accumulations:The US Experience[C/OL].AAPG ICE,2002.http://www.search and discovery.com/documents/abstracts/cairo2002/schenk.htm.
[13]赵靖舟.非常规油气有关概念、分类及资源潜力[J].天然气地球科学,2012,23(3):393-406.Zhao Jingzhou.Conception Classification and Resource Potential of Unconventional Hydrocarbons[J].Natural Gas Geoscience,2012,23(3):393-406.
[14]庞雄奇,姜振学,黄捍东,等.叠复连续油气藏成因机制、发育模式及分布预测[J].石油学报,2014,35(5):795-828.Pang Xiongqi,Jiang Zhenxue,Huang Handong,et al.Formation Mechanisms Distribution Models,and Prediction of Superimposed,Continuous Hydrocarbon Reservoirs[J].Acta Petrolei Sinica,2014,35(5):795-828.
[15]庞雄奇,黄捍东,林畅松,等.哈萨克斯坦Marsel探区叠复连续气田形成、分布与探测及资源储量评价[J].石油学报,2014,35(6):1012-1056.Pang Xiongqi,Huang Handong,Lin Changsong,et al.Formation,Distribution,Exploration,and Resource Reserve Assessment of Superimposed Continuous Gas Field in Marsel Exploration Area,Kazakhstan[J].Acta Petrolei Sinica,2014,35(6):1012-1056.
[16]陈冬霞,庞雄奇,李林涛,等.川西坳陷中段上三叠统须二段气水分布特征及成因机理[J].现代地质,2010,24(6):1117-1125.Chen Dongxia,Pang Xiongqi,Li Lintao,et al.GasWater Distribution Characteristics and Genetic Mechanism of the Second Sector of the Upper Triassic Xujiahe Formation in the Middle of the Western Sichuan Depression[J].Geoscience,2010,24(6):1117-1125.
[17]姜振学,林世国,庞雄奇,等.两种类型致密砂岩气藏对比[J].石油实验地质,2006,28(3):210-214.Jiang Zhenxue,Lin Shiguo,Pang Xiongqi,et al.The Comparison of Two Types of Tight Sand Gas Reservoir[J].Petroleum Geology&Experiment,2006,28(3):210-214.