松辽盆地徐家围子断陷玄武岩气藏储层的CO2封存潜力研究

摘要

The Daqing Oilfield, situated in Songliao Basin of Eastern China, is a famous oilfield for its largest production of crude oil in China. The Xujiaweizi fault depression, located in the north of the basin, covering an area of 4300 km2, developes large amount of basaltic hydrocarbon reservoirs. In this paper, we analyze the geological features and reservoir characteristics of basaltic hydrocarbon reservoir in the depression. Combined with mineral and chemical compositions of basalts from ten deep drilling wells of the Xujiaweizi fault depression, we evaluate the feasibility of CO2 sequestration in hydrocarbon reservoir of basaltic rocks, and then estimate the CO2 storage capacity from mineral trappimg and gas reservoir trapping in basaltic rocks in the depression. Our results show that reservoir spaces are favorable sites for CO2 sequestration and minerals of the reservoir rocks are easily suffered to carbonation. Meanwhile, the cap rocks of the hydrocarbon reservoirs can prevent the emission of CO2, and the stability of hydrocarbon reservoir can guarantee the safety of injected CO2. Therefore, hydrocarbon reservoir of basaltic rocks should be an idea target for CO2 sequestration. Estimates of theoretical capacity for CO2 storage assume that all the pore space freed up by the production of recoverable hydrocarbon reserves would be replaced by COj. In this study, the capacity of CO2 mineral sequestration has been calculated for the mafic minerals in basaltic rock of the hydrocarbon reservoir based on the principle of water-CO2-rock reaction. Moveover, the theoretical storage capacity of the gas reservoir trapping has been estimated based on gas resources in reserved basals from the local gasfield. According to our preliminary calculations, the potential capacity of mineral trappins for reaction with CO2 is about 89.33 × 108 tons, while capacity of gas reservoir trapping to CO2 storage is about 6.2 × 108 tons. So the total trapping capacity of CO2 sequestration for hydrocarbon reservoir of basaltic rocks from the Xujiaweizi fault depression is about 95.53 × 108 tons.%玄武岩油气藏储层一方面含有大量可与CO2反应生成碳酸盐的造岩矿物,另一方面又有枯竭油气藏的良好储(储集空间)、运(运移通道)、盖(盖层条件)和保(保存能力)等CO2封存优势,是潜力大、实施易、成本低和安全性高的碳汇靶区.该文选取了位于松辽盆地东北部的徐家围子断陷玄武岩气藏开展CO2封存潜力研究,在对该气藏地质特征和储层发育特征详细描述的基础上,结合玄武岩矿物组成和化学成分的鉴定分析结果,探讨该气藏的矿物固碳能力和油气储层固碳能力,并对其封存CO2的可行性进行了初步评价.研究表明,徐家围子断陷玄武岩气藏有着良好的储集空间,且易碳酸盐化,其盖层可阻止所充注CO2的逸散,稳定的圈闭条件可保证所充注CO2的安全性,因而是CO2封存的理想靶区.初步的定量计算结果表明,徐家围子断陷玄武岩油气藏的矿物固碳潜力约为89.33×108t,油气储层的封存能力约为6.2×108 t,总计约95.53×108t,具有十分可观的固碳潜力.