莺歌海盆地LD10区高含CO2天然气充注期次精细厘定与成藏模式

莺歌海盆地LD10区中深层黄流组?梅山组重力流水道、海底扇储层已被证实具有重大的天然气资源潜力.但是前期测试结果显示气藏中混有高含量CO₂气体.因此，精细厘定天然气充注期次，明确CH₄、CO₂等时空分布规律对规避高CO₂风险至关重要.本研究在对不同产状流体包裹体岩相学特征精细观察的基础上，综合激光拉曼光谱分析和包裹体显微测温技术识别出3幕不同成分天然气充注，时间分别为:4.0~2.9 Ma、2.0~1.2 Ma和0.8~0.3 Ma.其中，第一幕充注以烃类气为主，伴有少量有机CO₂和N₂；第二幕和第三幕充注以大量无机CO₂、烃类气为主，伴有少量N₂.结合天然气及烃源岩地化特征、天然气组分分析及输导体系识别，总结了LD10区的成藏模式，以期为研究区下一步天然气勘探开发和规避高含量CO₂风险提供依据. 

High CO2 Natural Gas Charging Events,Timing and Accumulation Pattern in LD10 Area of Yinggehai Basin

The gravity flow channel and subsea fan reservoirs of the middle and deep Huangliu Formation-Meishan Formation in Ledong 10 area of Yinggehai basin have been proved to have great natural gas resource potential. However, the preliminary test results show that the gas reservoir was mixed with high content of CO₂ gas. Therefore, fine determination of natural gas charging periods and clear spatial and temporal distribution rules such as CH₄ and CO₂ are crucial to avoid high CO₂ risks. In this study, based on the detailed observation of the petrographic characteristics of fluid inclusions with different occurrences, combined with laser Raman spectroscopy analysis and inclusions microscopic temperature measurement technology, three stages of natural gas charging with different components were identified at 4.0-2.9 Ma, 2.0-1.2 Ma and 0.8-0.3 Ma, respectively. Among them, the first stage of charging is mainly hydrocarbon gas, accompanied by a small amount of organic CO₂ and N₂. The second and third acts of charging were dominated by a large amount of inorganic CO₂ and hydrocarbon gas, accompanied by a small amount of N₂. Combined with the geochemical characteristics of natural gas and source rock, natural gas component analysis and transportation system identification, the accumulation model of Ledong 10 area is summarized, in order to provide a basis for the next gas exploration and development in the study area and to avoid the risk of high CO₂ content.