玛湖凹陷风南14井区风城组米氏旋回研究及固碳速率浅析

Milankovitch Cycle and Carbon Sequestration Rate of Fengnan 14 Well Area,Fengcheng Formation in Mahu Sag

玛湖凹陷风城组油气资源勘探潜力巨大,但因以细粒沉积物为主研究程度较低。利用频谱分析和小波分析法对玛湖凹陷风南14井区风城组自然伽马测井数据进行米兰科维奇旋回识别及划分。结果表明,研究区风城组保留了完整的米兰科维奇旋回信息,共识别出长偏心率旋回27个,建立了绝对天文年代标尺,证实了风城组的持续沉积时间约11.3 Ma。通过进一步的数据分析,得到风城组平均沉积速率为5.12 cm/kyr,其中碳酸盐岩平均沉积速率为2.83 cm/kyr。结合风城组沉积环境演化特点,揭示出沉积速率、碳酸盐岩沉积速率和固碳速率均与沉积环境密切相关,玛湖凹陷风南14井区风城组风一段后期、风二段中期—风三段早期是固碳速率较高时期。由此可见,“双碳”目标的实现与现代沉积环境研究具有内在联系。

The exploration potential of Fengcheng Formation in Mahu depression is huge,but the study are relatively low because it is mainly composed of fine-grained sediments.In this paper,spectrum analysis and wavelet analysis are used to identify and classify the Milankovitch cycle of Fengcheng Formation in Fengnan 14 well area.The results show that Fengcheng Formation in the study area retains complete Milankovitch cycle information,and 27 long eccentricity cycles were identified by consensus.The absolute astronomical chronological scale was established,which confirms that the continuous deposition time of the Fengcheng Formation was about 11.3 Ma.Through further analysis,the average deposition rate of Fengcheng Formation was 5.12 cm/kyr,and the average deposition rate of carbonate rock was 2.83 cm/kyr.Combined with the sedimentary environment evolution characteristics of Fengcheng Formation,it is revealed that the sedimentary rate,carbonate rock deposition rate and carbon sequestration rate are closely related to the sedimentary environment.The late period of Feng1st member of Fengcheng Formation,the middle period of Feng2nd member and the early period of Feng3rd member of Fengnan 14 well area in Mahu Sag are the periods of high carbon sequestration rate.It can be seen that the realization of"dual carbon"target is intrinsically related to the study of modern sedimentary environment.