摘要
四川盆地川中古隆起安岳震旦系—寒武系特大型气田的发现,揭示了该区下寒武统烃源岩巨大的天然气资源潜力。综合前人相关数据,构建了川中地区下寒武统烃源岩的地质—地球化学模型,应用PetroMod盆地模拟软件,结合Easy%RO模型,对川中古隆起的代表钻孔在关键地质时期的古地温梯度演化进行恢复,并对下寒武统烃源岩的生烃演化进行模拟。研究结果表明,中生代是川中古隆起下寒武统烃源岩油气生成与演化的关键时期,该时期其古地温梯度较高,并呈现逐渐降低的趋势。研究得到的古地温梯度模型为：3.5℃/100m（≥96Ma）—3.2℃/100m（65Ma）—2.7℃/100m（0Ma）。川中古隆起下寒武统烃源岩经历了早期生油、晚期生气的演化过程,烃源灶位置与文献报道的古裂陷槽基本吻合,其油、气累积生成强度分别可达（8~10）×106t/km2与（55~65）×108 m3/km2。古裂陷槽下寒武统烃源岩在主生油期（中—晚三叠世）生成的液态石油,可通过不整合面与断层组成的网状输导体系运移至磨溪—高石梯构造与威远—资阳构造形成古油藏;古油藏内的原油在侏罗纪—早白垩世期间完全裂解,原油裂解气是这2个构造下寒武统龙王庙组与上震旦统灯影组天然气藏的主要来源。
The Anyue Sinian-Cambrian large-scaled gas field was recently found in the central Sichuan Paleo- uplift, revealing a huge natural gas resource potential of Lower Cambrian shale in this area. By synthesizing the relevant data, this paper constructed the geology and geochemistry models of the Lower Cambrian shale in central Sichuan Basin. By the combined use of PetroMod basin modeling software and Easy%Ro model, the paleo-geothermal gradient evolution at critical geologic period of typical borehole at the paleo-uplift was recovered,and the hydrocarbon generation and evolution of Lower Cambrian shale in this area was simula- ted. The results show that, Mesozoic is the critical period for the generation and evolution of the Lower Cambrian shale in central Sichuan Basin. The paleo-geothermal gradient in Mesozoic was relatively higher, and it decreased gradually to the present. The paleo-geothermal gradient model obtained is. 3.5℃/100m （≥96Ma） -3.2℃/100m（65Ma）-2.7℃/100m（0Ma）. The Lower Cambrian shale in the central Sichuan Pa- leo-uplift has undergone an earlier oil generation and a later gas generation evolution history. The source kitchen is coincident with the paleo rift trough mentioned in this paper,with maximum oil and gas genera- tion intensity of （8-10） × 10^6t/km^2 and （55-65） ×1012 m^3/km^2 , respectively. The oil generated at the oil generation window （Middle-Irate Triassic） by Lower Cambrian shale in the paleo rift trough could migrate to the Gaoshiti and Weiyuan-Ziyang structure through zhe network migration system which is composed of the unconformities and faults,to form paleo-oil reservoirs. And the crude oil in the paleo-oil reservoirs was then cracked during the Jurassic to Early Cretaceous. The oil-cracked gas is the main source of the Upper Sinian Dengying Formation gas reservoir and Lower Cambrian Longwangmian Formation reservoir in the Gaoshiti and Weiyuan-Ziyang structure.
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2015年第10期1883-1892,共10页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2011ZX05008-002-40)
国家重点基础研究发展计划项目(编号:2012CB214705)
中国科学院战略性先导专项(编号:XDB10040300)联合资助
关键词
川中古隆起
下寒武统
烃源岩
生烃演化
天然气
Central Sichuan paleo-uplift
Lower Cambrian
Source rock
Hydrocarbon generation and evolution
Natural gas
