鄂尔多斯盆地JX井延长组砂岩固碳潜力分析

Carbon Sequestration Potential of Yanchang Formation Sandstone of JX Well,Ordos Basin

神华集团在我国CO2地下埋藏的潜在目标区(鄂尔多斯盆地)实施的CO2注入工程仍存在有关其注入层之上泥岩盖层安全性方面的争议。通过对与神华集团CO2注入井相邻且钻遇地层系统、岩石组合一致的JX井三叠系延长组(位于注入层之上)的研究预测一旦CO2透过盖层后的再续固碳能力。研究层位岩屑样品类型主要为长石砂岩和岩屑长石砂岩,其次为岩屑砂岩和岩屑石英砂岩;其物源区岩石类型主要为长英质火山岩、其次为中性火山岩及少量富含石英的沉积岩,具中性斜长岩成分特征;其上段(466~534 m)及下段(666~958 m)砂岩母岩受到弱—中等化学蚀变,并可能经历了再旋回过程;中段(534~666 m)砂岩母岩未受化学蚀变影响,并可能为第一次旋回沉积物。作为潜在的CO2再续固碳场所,延长组砂岩具有实现CO2矿物圈闭的物质条件及形成片钠铝石、方解石、铁白云石和菱铁矿等固碳矿物的潜力。

There are still some controversies surrounding the security of mudstone upon injection layer of CO2 injection project that implemented by Shenhua Group in the potential target area of CO2 underground embedded,Ordos Basin.Forecast the ability of adjourned carbon sequestration after CO2 penetrate cap rock by research of JX well Yanchang Formation( upon injection layer) that adjacent to injection well of Shenhua Group that the drilling stratigraphic system and rock assemblage are same. The samples of researching layer are mainly feldspar sandstone and lithic feldspar sandstone,followed by lithic sandstone and lithic quartz sandstone,and the rock types of provenance are mainly felsic volcanic rocks,followed by intermediate volcanic rocks and a small amount of quartz sedimentary rock,with componential characteristics of neutral anorthosite at the same time. The parent rocks of sandstone of the upper section( 466~ 534 m) and lower section( 666 ~ 958 m) suffered weak-medium chemical alteration,maybe they experienced recycling process,but the parent rocks of sandstone in the middle section( 534 ~ 666 m) did not suffer from chemical alteration and they are likely the first cycle sediment. As the place of adjourned carbon sequestration,Yanchang Formation has the material conditions of achieving CO2 mineral traps and potential of forming dawsonite,calcite,ankerite and siderite which called sequestration mineral.