Geochemical modelling of diagenetic reactions in a sub-arkosic sandstone
Geochemical modelling of diagenetic reactions in a sub-arkosic sandstone
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DOI：
10.1180/000985500546729
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发表时间：
2000-03
期刊：
影响因子：
1.5
通讯作者：
S. Barclay;R. Worden
中科院分区：
文献类型：
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作者：
S. Barclay;R. Worden
摘要为了模拟英国北海北部上侏罗统浊积岩储层Magnus砂岩的成岩作用，建立了反应路径模型。该模型涉及烃源岩来源的CO2进入黑质砂岩的通量，成功地再现了碎屑钾长石的溶解和自生石英、铁云母和伊利石的生长。CO2的生成发生在生油的主要阶段之前和期间，将烃源岩的成熟与黑砂岩的成岩模式联系起来，并将这种成岩作用限制在石油充注的早期阶段。地层水地球化学数据、ankerite的碳同位素数据、产出的气相CO2以及矿物胶结物中石油包裹体的存在为该模型提供了独立的佐证。对于相对不溶的物质，如SiO2和Al2O3，该模型是一个封闭系统，但对于CO2则是一个开放系统。有多达7个可能的速率控制步骤，包括：CO2的流入、钾长石的溶解、石英、铁白云石和伊利石的沉淀、SiO2和Al2O3从溶解点扩散到沉淀点，以及可能的Mg2+和Ca2+的流入速率。考虑到大量可能的控制，与现代流行的看法相反，石英沉淀的速率因此并不总是速率限制。
Abstract A reaction path model was constructed in a bid to simulate diagenesis in the Magnus Sandstone, an Upper Jurassic turbidite reservoir in the Northern North Sea, UKCS. The model, involving a flux of source rock-derived CO2 into an arkosic sandstone, successfully reproduced simultaneous dissolution of detrital K-feldspar and growth of authigenic quartz, ankerite and illite. Generation of CO2 occurred before and during the main phase of oil generation linking source rock maturation with patterns of diagenesis in arkosic sandstones and limiting this type of diagenesis to the earlier stages of oil charging. Independent corroborative evidence for the model is provided by formation water geochemical data, carbon isotope data from ankerite and produced gas phase CO2 and the presence of petroleum inclusions within the mineral cements. The model involves a closed system with respect to relatively insoluble species such as SiO2 and Al2O3 but is an open system with respect to CO2. There are up to seven possible rate-controlling steps including: influx of CO2, dissolution of K-feldspar, precipitation of quartz, ankerite and illite, diffusive transport of SiO2 and Al2O3 from the site of dissolution to the site of precipitation and possibly the rate of influx of Mg2+ and Ca2+. Given the large number of possible controls, and contrary to modern popular belief, the rate of quartz precipitation is thus not always rate limiting.