Song Wen, de Haas Thomas W, Fadaei Hossein, Sinton David
Department of Mechanical and Industrial Engineering, and Institute for Sustainable Energy, University of Toronto, Toronto, Canada.
Lab Chip. 2014 Nov 21;14(22):4382-90. doi: 10.1039/c4lc00608a.
We present a real-rock micromodel approach whereby microfluidic channels are fabricated in a naturally occurring mineral substrate. The method is applied to quantify calcite dissolution which is relevant to oil/gas recovery, CO2 sequestration, and wastewater disposal in carbonate formations - ubiquitous worldwide. The key advantage of this method is the inclusion of both the relevant substrate chemistry (not possible with conventional microfluidics) and real-time pore-scale resolution (not possible with core samples). Here, microchannels are etched into a natural calcite crystal and sealed with a glass slide. The approach is applied to study acidified brine flow through a single channel and a two-dimensional micromodel. The single-channel case conforms roughly to a 1-D analytical description, with crystal orientation influencing the local dissolution rate an additional 25%. The two-dimensional experiments show highly flow-directed dissolution and associated positive feedback wherein acid preferentially invades high conductivity flow paths, resulting in higher dissolution rates ('wormholing'). These experiments demonstrate and validate the approach of microfabricating fluid structures within natural minerals for transport and geochemical studies. More broadly, real-rock microfluidics open the door to a vast array of lab-on-a-chip opportunities in geology, reservoir engineering, and earth sciences.
我们提出了一种真实岩石微模型方法，即在天然矿物基质中制造微流体通道。该方法用于量化方解石溶解，这与全球普遍存在的碳酸盐地层中的油气开采、二氧化碳封存和废水处理相关。该方法的关键优势在于既包含了相关的基质化学性质（传统微流体技术无法实现）又具备实时孔隙尺度分辨率（岩心样品无法实现）。在此，微通道被蚀刻到天然方解石晶体中，并用载玻片密封。该方法用于研究酸化盐水通过单个通道和二维微模型的流动。单通道情况大致符合一维分析描述，晶体取向使局部溶解速率额外增加25%。二维实验显示出高度的流动导向溶解及相关的正反馈，即酸优先侵入高电导率流动路径，导致更高的溶解速率（“虫孔化”）。这些实验证明并验证了在天然矿物中微制造流体结构用于传输和地球化学研究的方法。更广泛地说，真实岩石微流体技术为地质、油藏工程和地球科学领域带来了大量芯片实验室的机会。
