Novel secure carbon sequestration methods

将研究两种迄今为止尚未考虑用于大规模固碳的新技术：泥浆注入(SI)和富含二氧化碳的气体注入。 硅是富碳固体(石油焦、生物固体……)的直接深部放置。对于生物固体SI，产生可回收的CH4，生物分解产生的二氧化碳溶解在地层水中。研究内容包括模拟溶解指数、生物固体的分解速率和产物、在地层水中的溶解行为以及由于溶解度不同而产生的气相色谱分离。生物固体SI的主要优点是废水和固体共同处理，同时以固体和溶解的形式安全地隔离碳，产生CH4，并能够共同处理其他废流。SI也可以在市政规模(50,000人口)上实施。 富含二氧化碳的气体注入(在部分膜浓缩后)可促进快速溶解，降低压缩成本，并降低纯超临界二氧化碳放置的高成本和严重的逃逸风险。适当的溶解速度可以通过最大化原位交换表面积、保持高浓度梯度以及共同注入废水和富含二氧化碳的气体来最大化混合来实现。研究问题包括：研究共注入和原位吸附(设想水平井)中的交换率，了解和最大限度地提高密度驱动的对流混合以维持高浓度梯度，浮力驱动分散的作用，二氧化碳和氮气的色谱分离(气体浓度变化)，以及改进气体混合物注入具有对流、弥散、浮力和溶解的多孔介质的预测模型以进行油藏模拟的方法。 这些都是新的世界级技术，具有高度的环境安全性；它们有望实现成本较低的长期碳固存，因为它们具有重大的积极协同作用，如共同处置其他废物流。从长远来看，它们将对碳封存政策产生重大影响。

Two novel technologies not heretofore considered for large-scale carbon-sequestration will be studied: slurry injection (SI), and carbon dioxide-enriched gas injection. SI is direct deep placement of C-rich solids (petcoke, biosolids...) into sediments; C is permanently sequestered as a solid, the injection liquid is waste water, and for biosolids SI, recoverable CH4 is generated and CO2 from biodecomposition dissolves in formation water. Research issues include simulation of SI, biosolids decomposition rates and products, dissolving behaviour in formation water and chromatographic produced gas separation because of different solubilities. Major advantages of biosolids SI are waste water and solids co-disposal while sequestering carbon securely in solid and dissolved form, CH4 generation, and ability to co-dispose other waste streams. SI can also be implemented at a municipal scale (50,000 population). CO2-enriched gas injection (after partial membrane enrichment) fosters rapid dissolution, reduces compression costs, and reduces high costs and serious escape hazards of pure supercritical CO2 placement. Adequate dissolution rates can be achieved by maximizing in situ surface area for exchange, maintaining a high concentration gradient, and co-injecting waste water and CO2-enriched gas to maximize mixing. Research issues include study of exchange rates in co-injection and adsorption in situ (horizontal wells are envisioned), understanding and maximizing density-driven convective mixing in situ to sustain high concentration gradients, the role of buoyancy-driven dispersion, chromatographic separation of CO2 and N2 (changes in gas concentration), and means of improving predictive models for gas mixture injection into porous media with convection, dispersion, buoyancy and dissolution to undertake reservoir simulation. These are novel world-class technologies with high environmentally secure; they promise to achieve lower-cost long-term C-sequestration because of major positive synergies such as co-disposal of other waste streams. They will have a major impact on carbon sequestration policy in the long run.