断层流体锶、碳、氧同位素示踪评价断层垂向封闭性——以焦石坝背斜带为例

发布时间：2019-04-18 17:02

【摘要】：锶同位素不易分馏、年代可对比的特性决定其能够作为有效的断层流体示踪指标。氧同位素能反映温度、流体等因素,碳同位素能反映有机质的影响,是锶同位素的有力补充。利用流体示踪图可以判断断层不同部位开启的期次与可能联通范围。针对四川盆地焦石坝背斜带周缘的断层,利用脉体锶、碳、氧同位素开展断层垂向封闭性评价。评价结果表明:焦石坝地区志留系以下地层联通,存在一期深部壳源富锶流体,志留系下部的流体未通过断层向上运移。该地区后期至少经过两期构造运动,针对志留系龙马溪组页岩气,焦石坝背斜带周边不同断层的垂向封闭性具有明显差异。从平面上看,方斗山断裂带中部、大耳山断裂带南部、乌江断裂带南部断层垂向封闭性差;大耳山断裂带北部、乌江断裂带北部、天台场断裂带南部断层垂向封闭性中等;方斗山断裂带北部、南部、天台场断裂带北部垂向封闭性好。
[Abstract]:Strontium isotopes are not easy to fractionation and can be used as an effective tracer index of fault fluids due to their age-comparable characteristics. Oxygen isotopes can reflect temperature, fluid and other factors, and carbon isotopes can reflect the influence of organic matter, which is a powerful complement to strontium isotopes. Fluid tracer map can be used to judge the opening period and possible connecting range of different parts of the fault. In view of the faults around Jiaoshiba anticline zone in Sichuan Basin, the vertical sealing ability of faults is evaluated by means of strontium, carbon and oxygen isotopes of vein bodies. The evaluation results show that there exists a deep crust source strontium-rich fluid in the lower Silurian strata of Jiaoshiba area, and the fluid in the lower Silurian system does not migrate upward through the fault. After at least two periods of tectonic movement, the vertical sealing properties of different faults around the Longmaxi formation shale gas and Jiaoshiba anticline zone in Silurian system are obviously different in the later period of this area. From the plane point of view, the vertical sealing of faults in the middle of Fangdushan fault zone, in the south of Darshan fault zone and in the south of Wujiang fault zone is poor, and the vertical closure of faults in the north of Dar'ershan fault zone, in the north of Wujiang fault zone and in the south of Tiantachang fault zone is moderate. Fangduoshan fault zone north, south, the northern Tiantachang fault zone vertical sealing is good.
【作者单位】：中国石油大学(北京)地球科学学院;中国石化石油勘探开发研究院;
【基金】：中国石化科技部项目(P16083)~~
【分类号】：P618.13

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