Migration of CO2 through North Sea Geological Carbon Storage Sites: Impact of Faults, Geological Heterogeneities and Dissolution

二氧化碳通过北海地质碳封存点的迁移：断层、地质异质性和溶解的影响

• 批准号: NE/N016084/1
• 负责人: Jerome Neufeld
• 金额: $ 81.36万
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FN016084%2F1
• 关键词: Migration; CO2; through; North; Sea

The storage of CO2 in deep geological formations is one of the chief technological means of reducing anthropogenic emissions of CO2 to the atmosphere. The process requires capturing CO2 at source (e.g. coal-fired power plants), transporting CO2 to the injection site, and pumping liquefied CO2 into kilometre deep, porous reservoirs that are typically initially saturated in saline water or previously contained oil or gas. Initially, buoyant CO2 tends to rise through the porous reservoir until it is trapped by an impermeable horizon, in the same way that oil or gas has been trapped over millennia. Subsequently, buoyant CO2 may be more securely trapped by dissolving CO2 into water (carbonated water is more dense than non-carbonated water and will sink), or by capillary forces acting to hold the CO2 in the small confines of the pore space. Any risk of buoyant CO2 migrating through the overburden is therefore reduced by these trapping processes. Constraining the rates of dissolution and capillary trapping in realistic geological overburden is a key component of strategies to quantify and reduce the risks of leakage. The UK is geologically well placed to implement offshore CO2 storage, with many potential reservoirs in the North Sea.This proposal will improve our understanding of the risks of leakage through the overburden by quantifying trapping rates in faults and heterogeneous strata typical of the overburden of North Sea reservoirs, and by quantifying our ability to seismically detect any CO2 in the overburden. CO2 is less viscous than water and will finger along more permeable layers. Sedimentary strata exhibit large variations in permeability on all scales that will substantially increase the rates at which CO2 dissolves in the formation waters.The analysis, while general in scope and resultant techniques, is applied to the Goldeneye field, a target for CO2 storage and a candidate for the Government's CCS commercialisation competition. Our approach is to geologically characterise the relevant geological heterogeneity within the overburden, and to map the structure and propensity for fluid flow within faults in that locality. Drill core provides samples of rock (5x20 cm) that can then be interrogated in the laboratory. We will directly image, at conditions typical of the overburden, the rates of fluid flow, dissolution, and capillary trapping both at the scale of individual pores within the rock (microns) and over the length of the core (centimetres). Geochemical analysis of the fluids will allow us to measure in situ dissolution and precipitation rates in our core flooding experiments. In order to determine how rates of flow and trapping may be applied at the scale of the reservoir and overburden the results must be interpreted in light of flow through 1-100 centimetre scale geological heterogeneities and along faults. To assess the impact of heterogeneities on the rates of trapping we will construct simplified models of flow along predominantly layered strata, or along cross-cutting faults, along with laboratory analogue experiments in which we can optically assess trapping rates and thereby provide a firm benchmark for our predictions. Finally, at larger scales, we will image flow up chimney structures in existing CO2 experiments (eg Sleipner in the North Sea) and thus provide quantitative estimates of our ability to seismically resolve leakage pathways in the storage overburden. Our proposal will develop tools needed to geologically characterise the North Sea overburden, provide quantitative estimates of trapping rates in geologically complex overburden and fault complexes, and demonstrate the ability to seismically resolve fluid flow pathways. To date geological CO2 storage has been demonstrated at relatively safe storage sites. This work would greatly expand the potential for geological CO2 storage by quantifying the potential risks associated with leakage in more geologically complex storage sites.

在深部地质构造中储存二氧化碳是减少人类活动向大气排放二氧化碳的主要技术手段之一。这一过程需要从源头(例如燃煤发电厂)捕获二氧化碳，将二氧化碳输送到注入地点，并将液化二氧化碳泵入一公里深的多孔储层，这些储层最初通常是饱和的咸水或以前含有的石油或天然气。最初，漂浮的二氧化碳往往会通过多孔的储油层上升，直到被不透水的地层困住，就像石油或天然气被困了数千年一样。因此，通过将二氧化碳溶解到水中(碳化水比非碳化水密度更大，会下沉)，或者通过毛细管力将二氧化碳保持在孔隙空间的小范围内，可以更安全地捕获浮力二氧化碳。因此，通过这些捕获过程，浮力二氧化碳通过覆盖层迁移的任何风险都会降低。限制真实地质覆盖层中的溶解和毛细管捕获的速度是量化和减少渗漏风险的战略的关键组成部分。英国在地质上处于实施近海二氧化碳储存的有利位置，在北海有许多潜在的储油层。这项提议将通过量化北海储集层覆盖层中典型的断层和非均质地层的捕获率，并通过量化我们在地震中检测覆盖层中任何二氧化碳的能力，来提高我们对覆盖层泄漏风险的理解。二氧化碳的粘性比水小，会沿着更具渗透性的层移动。沉积地层的渗透率在所有尺度上都表现出很大的差异，这将大大增加二氧化碳在地层水中的溶解速度。虽然这项分析的范围和结果技术一般，但适用于黄金眼油田，该油田是二氧化碳储存的目标，也是政府CCS商业化竞赛的候选者。我们的方法是对覆盖层内相关的地质非均质性进行地质特征描述，并绘制该地区断层内流体流动的结构和倾向图。钻芯提供了岩石样本(5x20厘米)，然后可以在实验室进行测试。我们将在覆岩的典型条件下，直接成像岩石内单个孔隙(微米)和岩心长度(厘米)上的流体流动、溶解和毛细管捕获的速度。流体的地化分析将使我们能够在岩心驱油实验中测量就地溶解和沉淀速率。为了确定如何在储集层和覆盖层的尺度上应用流量和圈闭，必须根据流经1-100厘米尺度的地质非均质性和沿断层的流量来解释结果。为了评估非均质性对圈闭速率的影响，我们将构建沿主要层状地层或横切断层的简化流动模型，以及实验室模拟实验，在实验室模拟实验中，我们可以光学地评估圈闭速率，从而为我们的预测提供一个可靠的基准。最后，在更大的尺度上，我们将在现有的二氧化碳实验(例如北海的Sleipner)中描绘沿烟囱结构向上流动的图像，从而提供对我们通过地震解决储存覆盖层中泄漏路径的能力的定量估计。我们的计划将开发所需的工具，以确定北海覆盖层的地质特征，提供对地质复杂覆盖层和断层复合体中圈闭速率的定量估计，并展示从地震角度解决流体流动路径的能力。到目前为止，在相对安全的存储地点已经证明了地质上的二氧化碳储存。这项工作将通过量化与地质更复杂的储存点的泄漏相关的潜在风险，极大地扩大地质二氧化碳储存的潜力。

项目成果

Axisymmetric gravity currents in anisotropic porous media

各向异性多孔介质中的轴对称重力流

• DOI: 10.1017/jfm.2022.922
• 发表时间: 2022
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Benham G

Two-phase gravity currents in layered porous media

层状多孔介质中的两相重力流

• DOI: 10.1017/jfm.2021.523
• 发表时间: 2021
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: Benham G

Upscaling multiphase viscous-to-capillary transitions in heterogeneous porous media

• DOI: 10.1017/jfm.2020.1134
• 发表时间: 2021-02
• 期刊: Journal of Fluid Mechanics
• 影响因子: 3.7
• 作者: G. Benham;M. Bickle;J. Neufeld