柴达木盆地北缘侏罗系油气前景
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摘要
柴达木盆地北缘侏罗系残余地层分布极复杂，在其中虽已发现多种类型油气藏，探明石油储量却十分有限。该地区早、中侏罗世沉积了数百米至千余米厚的湖相及沼泽相地层。根据这一地区近年的勘探进展，结合前人工作，认为：①盆地北缘的中生界厚度多为1～2km，主要是侏罗系，埋藏深度多超过4．5km；②侏罗系烃源岩主要是其暗色泥质岩，其次为煤层，母质类型多为过渡型和腐殖型，有机质丰度高，成熟度也较高，油气生成量丰富后储集层系多，主要分布于中、上侏罗统和第三系的下干柴询组、上干柴询组，储集物性较好，有两大类6种类型的生、储、盖组合和油气运聚类型；④侏罗系圈闭以构造背景上发育的多种复合类型圈闭为主，由于难获得良好的深层地震资料，导致辨清圈闭困难，勘探难度大。今后该地区的勘探重点是查清油源层分布和深层圈闭。提出冷湖构造带和马海、南八仙背斜构造带是近期勘探最有利和最现实的地区。
The distribution of residual strata of Jurassic in northern margin of Qaidam basin is very complicated, among which manytypes of oil and gas pools have been found, but their accumulative proved reserves are very limited. Several hundred to onethousand meter thick lacustrine and smash strata deposited in this region during Early and Middle Jurassic- According to therecent exploration results and combined with predecessor's work, it is recognized that: The Mesozoic, dominated byJurassic, in the northern margin of the basin is commonly l to 2 km thick, with a buried depth of over 4. 5 km;Hydrocarbon source rocks of Jurassic are mainly duck muddy stones and then coal beds, and the kerogin is mainly oftransitional and humic type, with a high abundance of organic matter, a high maturity and big amount of oil and gasgeneration; Reservoirs have many layers mainly distributed in Lower and Upper Ganchaigou FM, with good petrophysicalproperties. There are two major categories with six types of source reservoir-cap assemblages and oil and gas migration andaccumulation; Jurassic traps are dominated by many kinds of composite structures which are very difficult to be identifieddue to lack of good deep seismic data. lt is considered that the exploration focus in the future should be put on the thoroughinvestigation of distributions of source beds and deep traps, taking the Lenghu structural belt and Mahai and Nanbaxiananticlinal zone as the most favourable and practical regions.
The distribution of residual strata of Jurassic in northern margin of Qaidam basin is very complicated, among which manytypes of oil and gas pools have been found, but their accumulative proved reserves are very limited. Several hundred to onethousand meter thick lacustrine and smash strata deposited in this region during Early and Middle Jurassic- According to therecent exploration results and combined with predecessor's work, it is recognized that: The Mesozoic, dominated byJurassic, in the northern margin of the basin is commonly l to 2 km thick, with a buried depth of over 4. 5 km;Hydrocarbon source rocks of Jurassic are mainly duck muddy stones and then coal beds, and the kerogin is mainly oftransitional and humic type, with a high abundance of organic matter, a high maturity and big amount of oil and gasgeneration; Reservoirs have many layers mainly distributed in Lower and Upper Ganchaigou FM, with good petrophysicalproperties. There are two major categories with six types of source reservoir-cap assemblages and oil and gas migration andaccumulation; Jurassic traps are dominated by many kinds of composite structures which are very difficult to be identifieddue to lack of good deep seismic data. lt is considered that the exploration focus in the future should be put on the thoroughinvestigation of distributions of source beds and deep traps, taking the Lenghu structural belt and Mahai and Nanbaxiananticlinal zone as the most favourable and practical regions.
引文
1青藏油气区石油地质志编写组(编):中国石油地志·卷十四·青藏油气区;石油工业出版社(北京),1990,79。
2郑海翔 张选阳:青藏高原大地构造问题;见:青藏高原地质文集,地质出版社(北京),1988,80～90。
3何元良:青海省陆相佚罗系划分的初步探讨;见:青藏高原地质文集,地质出版社(北京),1988,165～181。
4汤锡元等:柴达木盆地北缘块断带石油地质特征;石油与天然气地质,1986,7(2)185～186。
5戴金星等:中亚煤成气聚集域形成及其源岩──中亚煤成气聚集域研究之一;石油勘探与开发,1995,22(3)1～6。
6王明儒:柴达木盆地地震相模式;石油实验地质,1993,15(3) 231～233。
2郑海翔 张选阳:青藏高原大地构造问题;见:青藏高原地质文集,地质出版社(北京),1988,80～90。
3何元良:青海省陆相佚罗系划分的初步探讨;见:青藏高原地质文集,地质出版社(北京),1988,165～181。
4汤锡元等:柴达木盆地北缘块断带石油地质特征;石油与天然气地质,1986,7(2)185～186。
5戴金星等:中亚煤成气聚集域形成及其源岩──中亚煤成气聚集域研究之一;石油勘探与开发,1995,22(3)1～6。
6王明儒:柴达木盆地地震相模式;石油实验地质,1993,15(3) 231～233。
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