石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (5): 1095-1105.doi: 10.11743/ogg20190515

• 油气地质 • 上一篇    下一篇

柴北缘深层天然气成藏条件及有利勘探方向

田继先1, 李剑1, 曾旭1, 孔骅1, 王鹏2, 沙威2, 王牧2, 石正灏2, 宋德康2   

  1. 1. 中国石油 勘探开发研究院, 河北 廊坊 065007;
    2. 中国石油 青海油田公司 勘探开发研究院, 甘肃 敦煌 736200
  • 收稿日期:2018-06-13 修回日期:2019-05-08 出版日期:2019-10-28 发布日期:2019-08-17
  • 作者简介:田继先(1981-),男,工程师,油气地质。E-mail:tjx69@petrochina.com.cn。
  • 基金资助:
    中国石油重大科技专项(2016E-01);国家科技重大专项(2016ZX05007)。

Accumulation conditions and favorable plays for deep gas exploration at the northern margin of Qaidam Basin

Tian Jixian1, Li Jian1, Zeng Xu1, Kong Hua1, Wang Peng2, Sha Wei2, Wang Mu2, Shi Zhenghao2, Song Dekang2   

  1. 1. Research Institute of Petroleum Exploration and Development, PetroChina, Langfang, Hebei 065007, China;
    2. Exploration and Development Research Institute of Qinghai Oilfield Co., Ltd., PetroChina, Dunhuang, Gansu 736200, China
  • Received:2018-06-13 Revised:2019-05-08 Online:2019-10-28 Published:2019-08-17

摘要: 柴北缘深层天然气勘探程度低,资源潜力大,天然气成藏条件及勘探方向尚不明确,制约了天然气勘探进程。基于地震、地质、地化及钻井等资料的研究,从烃源岩、储层、构造及输导体系等方面,综合分析了柴北缘深层天然气藏的成藏条件,结合已有勘探成果和地质条件,指出了深层天然气有利勘探方向。结果表明,深层侏罗系分布广,阿尔金山前西段存在侏罗系生烃凹陷,深层高-过成熟度烃源岩生气潜力大;基岩风化壳和次生孔隙发育的碎屑岩可作为深层有效储层,基岩储层物性不受深度控制,深层发育碎屑岩优质储层;广泛分布的以断裂为主的输导体系有利于超深层烃源岩生成的天然气纵向和横向运移;多期构造活动使得柴北缘深层形成多种类型的圈闭,烃源岩持续生烃有利于这些深层圈闭早期、多期成藏。在以上研究成果基础上,指出深大断裂发育的生烃凹陷周围圈闭是深层天然气聚集有利区,盆缘古隆起以及晚期构造带上大型背斜圈闭层具有良好的勘探前景,其中阿尔金山前深层是最现实的勘探领域。

关键词: 成藏条件, 输导体系, 基岩储层, 深层气藏, 侏罗系, 柴达木盆地北缘

Abstract: The potential of deep natural gas resources is great at the northern margin of Qaidam Basin,but it is lower in exploration maturity.The gas accumulation conditions and plays for exploration are still to be revealed,restricting the exploration progress of natural gas.Given studies on seismic,geological,geochemical and drilling data,we analyzed the conditions for gas accumulation in deep strata at the northern margin of Qaidam Basin comprehensively in terms of source rock,reservoir,structure,and carrier system,and pointed out the favorable plays for deep gas exploration based on the existing exploration results and geological conditions.The results show that due to the widespread distribution of the Jurassic,a new Jurassic hydrocarbon generation depression is discovered in the western segment of the piedmont of Altun Mountain,featuring high potential of hydrocarbon generation in the deep high-to-over-mature source rocks.Both the weathering crust of bedrocks and clastic rocks with well-developed secondary pores may serve as the effective reservoirs in deep horizons:the physical properties of the former are not controlled by depth,and the latter were well developed characterized by high quality in deep horizons.The fracture-dominated carrier system of wide distribution is conducive to the vertical and horizontal migration of natural gas generated from ultra-deep source rocks.Multi-stage tectonic activities have led to the formation of multiple types of traps in deep layers at the northern margin of Qaidam Basin; meanwhile the continuous hydrocarbon generation of source rocks have facilitated the earlier,multi-stage hydrocarbon accumulation in these deep traps.In view of the above results,it is concluded that the traps around the hydrocarbon generation sag with well-developed deep large faults are favorable for deep gas accumulation,and the paleo-uplift at the basin margin and the large-scale anticlinal traps in the late tectonic zone are prospective areas for hydrocarbon exploration,with the deep layers in the piedmont of the Altun Mountain being the most prospective one.

Key words: accumulation condition, carrier system, bedrock reservoir, deep gas reservoir, Jurassic, northern margin of the Qaidam Basin

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