松辽盆地北部火山岩CO2脱气参数及其对CO2资源量估算的意义

为了定量评价火山岩脱CO2气量的潜力，选择松辽盆地北部火山岩进行了低温脱气实验。将火山岩加热到250℃时，脱出挥发份总量为0.0299～0.0790ml/g；其中CO2脱出量为0.0218～0.0706 ml/g（0.429～1.387wt％）。脱挥发份总量与其中CO2量具有良好的正线性相关；挥发份以CO2气为主，其次是Ｎ2气，还伴有H2、CO、CH4等还原性气体，以及更少量的低碳烷烃；基性火山岩比中、酸性火山岩脱出CO2数量较多。火山岩吸附大量CO2气，成为充足气源，火山岩脱出的吸附气主要是辗转而来的深源气，火山岩成为探索幔源气成藏的主要源岩，尤其是基性火山岩。估算CO2资源量，可将250℃时火山岩挥发份含量作为岩石挥发份及残余CO2量的下限值，而全岩分析的总碳含量可作为CO2脱出量的上限值。

Degassing Parameter of Carbon Dioxide in Volcanic Rocks in the Northern Songliao Basin and Its Significance in Forecasting Geological Resource of Carbon Dioxide

It was usually thought that extrusive rocks were not gas source of carbon dioxide reservoirs, because most of the gas was released directly into atmosphere in the cooling process. Whereas recently some researches indicated that CO2 gas of Changdedong gas reservoir was mainly adsorbing gas in volcanic rocks, and post-release of adsorbing gas was important to form the gas reservoir. In order to evaluate the potential and possibility for adsorbing CO2 gas forming gas reservoirs quantificationally, low-temperature (250℃) degassing experiments of volcanic rocks in northern Songliao basin were done. The amounts of released volatile are 0.0299~0.0790ml/g, and those of CO2 are 0.0218~0.0706 ml/g (0.429~1.387wt％). The relationship of the amounts between volatile and carbon dioxide is positively linear. The main component of volatiles is carbon dioxide, and the secondly is N2, and some associated components are deoxidized gases, such as H2, CO, CH4, as well as fewer amounts of low-carbon alkanes. Both the content in volatile and degassing amount of CO2 have an inverse relation with the content of hydrocarbon. There is a negative correlation between the CO2 degassing amount and SiO2 content of volcanic rocks. Volcanic rocks, particularly the basic ones, can adsorb vast amount of carbon dioxide and act as the major gas source rocks. When forecasting geological resource of carbon dioxide, the amount of volatile of volcanic rocks at 250℃ can be treated as the lower limit of the content of volatile and remnant CO2, while the content of total carbon as the upper limit of the amount of degassing CO2.