松辽盆地大陆科学钻探井天然氢气吸附特征及赋存规律

Adsorption characteristics and occurrence pattern of natural hydrogen in a continental scientific drilling well of the Songliao Basin

韩双彪 王缙 黄劼 王成善

Shuangbiao HAN Jin WANG Jie HUANG Chengshan WANG

松辽盆地大陆科学钻探井松科2井中发现了高含量天然氢气，氢气在不同类型岩石储层中吸附特征复杂。通过钻探井天然氢异常显示储层实验测试数据并结合分子动力学方法研究了不同地质条件下不同类型岩石储层中天然氢气吸附特征，根据温度、压力、孔隙直径、孔隙类型及气体竞争吸附因素研究了天然氢气赋存变化规律。研究结果表明：①天然氢异常显示储层中氢气含量最高达26.89 %，矿物以黏土矿物及石英为主，有机质含量相对较高。有机质与黏土矿物的孔隙为富氢天然气吸附孔隙，储层中相对较小尺寸孔隙（孔径0.4 ~ 7.0 nm）可能是氢气赋存的主要空间。②当氢气与甲烷共同存在于孔径大于0.5 nm的孔隙中时，吸附态氢气含量较低，孔隙尺寸变大使得游离态氢气含量升高。蒙脱石吸附氢气能力最强。甲烷的竞争吸附会减少孔隙内的氢气含量，不利于氢气富集。③压力增大使孔隙对氢气吸附能力明显增强，温度升高则会使氢气脱附作用增强。石英与伊利石孔隙中吸附态氢气会随着温度升高更容易转化为游离态。微孔对氢气的吸附作用较强，氢气吸附量主要在微孔中。④研究区深部富铁岩层或地幔活动具有充足的氢气供给，天然氢气可以赋存于深部沉积储层中。烃类气体的生成、氢气吸附向游离状态转化及逸散作用使得氢气含量逐渐降低，形成了以甲烷为主的富氢天然气聚集区域。

High-content natural hydrogen has been discovered in well SK-2 of the Continental Scientific Drilling Project of the Cretaceous Songliao Basin. Hydrogen gas in reservoirs with varying lithologies exhibits different complex adsorption characteristics. Using experimental data from reservoirs with natural hydrogen anomaly shows in well SK-2 and molecular dynamics methodology， we investigate the adsorption characteristics of natural hydrogen in reservoirs with varying lithologies under different geologic conditions. Furthermore， we explore the occurrence variation pattern of natural hydrogen based on temperature， pressure， pore diameter， pore type， and competitive adsorption of gases. The results indicate that the reservoirs with natural hydrogen anomaly shows exhibit a hydrogen content of up to 26.89 %， a mineral composition dominated by clay and quartz and a relatively high organic matter content. Pores of organic matter and clay in these reservoirs absorb natural gas rich in hydrogen. Among them， pores with relatively small sizes （0.4 ~ 7.0 nm in diameter） may serve as the primary spaces for hydrogen gas occurrence. In pores larger than 0.5 nm that contain both hydrogen gas and methane， the adsorbed hydrogen gas content remains low， while the content of free hydrogen gas increases with pore size. Montmorillonite demonstrates the highest adsorption capacity for hydrogen gas. However， competitive adsorption for methane reduces the hydrogen gas content in pores， hindering its enrichment. An increase in pressure significantly enhances the adsorption capacity of pores for hydrogen gas， whereas a rising temperature intensifies their desorption process for hydrogen gas. As the temperature increases， adsorbed hydrogen gas in pores of quartz and illite is more prone to convert into free gas. Micropores manifest a relatively high adsorption capacity for hydrogen gas， serving as the primary spaces for the occurrence of adsorbed hydrogen gas. The deep iron-rich rocks or mantle activity in the study area ensure sufficient hydrogen gas supply， enabling natural hydrogen generated to accumulate in deep sedimentary reservoirs. The hydrogen gas content gradually decreases with the generation of hydrocarbon gases， the conversion of adsorbed hydrogen gas into free gas， and hydrogen gas dissipation， leading to the formation of hydrogen-rich natural gas accumulation zones dominated by methane.

10.11743/ogg20250209