Geochemistry of CO2 sequestration in the Jurassic Navajo Sandstone, Colorado Plateau, Utah
Geochemistry of CO2 sequestration in the Jurassic Navajo Sandstone, Colorado Plateau, Utah
复制标题
犹他州科罗拉多高原侏罗纪纳瓦霍砂岩中二氧化碳封存的地球化学
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
M. Chan
中科院分区：
文献类型：
--
作者：
W. T. Parry;C. Forster;James P. Evans;B. Bowen;M. Chan
犹他州的科罗拉多高原上的侏罗纪纳瓦霍砂岩可被考虑用于封存CO2，因为其厚度大、分布广、具有高孔隙度和渗透率、通常为水平至平缓褶皱、相对于密封层有利地定位，并且位于许多CO2的大点源之下。然而，断层常见的科罗拉多高原可能提供的途径泄漏的二氧化碳类似于今天的间歇泉和二氧化碳充泉水。纳瓦霍砂岩中存在的天然地下水包括一系列低盐度、含高碳酸氢盐的中盐度和高盐度沃茨。高盐度的沃茨可能是在自流压力作用下从较深的地层中运移而来，也可能来自于前侏罗纪岩石中蒸发岩的溶解。这些特点使得纳瓦霍砂岩成为一个很好的模拟研究地球化学的CO2注入到深咸水层。CO2在溶液中的储存率是CO2在这些沃茨中的溶解度的函数，其取决于盐度、温度和压力。地球化学模拟表明，温度最低、含盐量最少的水在溶液中含有最多的二氧化碳。在水中溶解二氧化碳会降低pH值，因此没有矿物质沉淀，纳瓦霍砂岩只含有少量可能消耗H+的矿物质。在整个500年的砂岩中溶解CO2与钾长石和次要粘土和方解石产生的酸性水的反应消耗很少的H+，只产生少量的产品矿物。纳瓦霍砂岩可能不会储存大量的CO2作为矿物沉淀物，因此，CO2的储存量将受到其在原位水中的溶解度和在孔隙空间中作为游离CO2储存的限制。
The Jurassic Navajo Sandstone on the Colorado Plateau of Utah may be considered for sequestration of CO2, because it is thick, widely distributed, has a high porosity and permeability, is typically horizontal to gently folded, is favorably located with respect to seal strata, and underlies many large point sources of CO2. However, faulting common on the Colorado Plateau may provide pathways for leakage of the CO2 similar to present-day geysers and CO2-charged springs. Natural groundwater present in the Navajo Sandstone includes a range of low-salinity, moderate-salinity with high bicarbonate, and high-salinity waters. Higher salinity waters may have moved from deeper strata under artesian pressures or originated from solution of evaporite in pre-Jurassic rocks. These characteristics make the Navajo Sandstone an excellent analog for examining the geochemistry of CO2 injection into deep saline aquifers. The storativity of CO2 in solution is a function of the solubility of CO2 in these waters, which is dependent on salinity, temperature, and pressure. Geochemical modeling shows that the coolest, least saline water can contain the most CO2 in solution. Dissolving CO2 in the water lowers the pH, so that no minerals precipitate, and the Navajo Sandstone contains only small amounts of mineral that may consume the H+. The reaction of the acidic water produced by dissolving CO2 with K-feldspar and minor clays and calcite in the sandstone throughout 500 yr consumes little H+ and produces only small amounts of product minerals. The Navajo Sandstone likely would not store significant CO2 as mineral precipitate, and thus, stored volumes of CO2 would be limited by its solubility in the in-situ water and storage as free CO2 in pore space.