Interaction between solid, liquid and biological components of the natural porous media - an experimental approach

地下多孔介质通常由固体、液体和生物组分组成。通过该介质的资源的存储容量和交付能力主要由这些组件之间的相互作用以及复杂相互作用的副产品决定。例如，当沙粒被一种微米级的非常细粒的材料(如碎屑粘土)覆盖时，其他块状矿物不能在颗粒上沉淀。这一简单的过程使孔隙网络保持开放，并允许流体通过孔隙流动。虽然这种关系是众所周知的，但粘土包衣的机理还不完全清楚。几十年来，静电力被认为是微米级粘土颗粒附着在砂粒上的主要过程。然而，最近的观察表明，生物控制(主要是生物膜)对这一过程有重要的输入，应该进行详细的研究。这项PHD研究针对通常被忽视的多孔介质成分，并用实验方法研究了生物膜与其他成分的相互作用。通过这样做，这项研究旨在更好地了解多孔介质的演变，这反过来又为资源管理、勘探和基础设施设计提供了宝贵的投入。这项研究将从分子到微观到区域/盆地的不同尺度进行研究，概述如下。*生物膜与多孔介质的两个选定固体成分(沙粒和粘土颗粒)的相互作用以及重要生态因素(如pH、盐度、总有机碳)的贡献将通过使用天然微生物群落的受控实验室实验来研究。与沙粒(生物膜)和液态(自由生活)相关的群落组成将通过DNA测序(使用系统发育标记基因)进行分析。*将通过成像技术(例如共焦激光扫描和扫描电子显微镜)评估沙-粘土-生物膜的相互作用。实验室实验的结果将用于描述各种自然环境(包括最近的地表和古代的地下例子)中的沙-粘土-生物膜相互作用的特征。*将在沉积学和孔隙尺度的储层质量演化的背景下研究粘土包裹的颗粒在储层中的空间分布(盆地尺度)以及对这种分布的控制。

The subsurface porous media is typically composed of solid, liquid and biological components. The storage capacity and deliverability of the resources through this media is mainly dictated by the interaction between these components and by the by-products of the complex interactions. For example, when a sand grain is coated by a micrometre-scale very fine grained material (such as detrital clay), other blocky minerals cannot precipitate on the grain. This simple process keeps the pore network open and allows fluids to flow through the pores. Although this relationship is well known, the clay coating mechanism is not fully understood. Over few decades, electrostatic forces are accepted to be the main process of attaching micrometre-scale clay particles to sand grains. Recent observations, however, show that biological control (mostly biofilms) has a significant input to the process and should be investigated in detail.This PhD study targets the commonly overlooked component of porous media and investigates the interaction of biofilms with other components with an experimental approach. By doing this, the study aims to develop a better understanding of the evolution of the porous media, which in turn provide a valuable input to resource management, exploration and infrastructure design. The study will investigate the topic in various scales ranging from molecular to microscopic to regional/basinal scale as outline below.* The interaction of biofilms with two selected solid components of the porous media (sand grain and clay particles) and the contribution of important ecological factors (e.g. pH, salinity, TOC) will be investigated by controlled laboratory experiments using naturally-derived microbial communities. The community composition associated with sand grains (biofilm) and liquid phase (free-living) will be analysed by DNA sequencing (using phylogenetic marker genes). * The sand-clay-biofilm interaction will be assessed by imaging techniques (e.g. confocal-laser scanning and scanning electron microscopy). The results from laboratory experiment, will be used to characterised sand-clay-biofilm interaction in various natural environments (including recent surface and ancient subsurface examples) using similar analytical techniques.* The spatial distribution of clay coated grains in reservoirs (basin scale) and the controls on this distribution will be studied in the context of sedimentology and pore-scale reservoir quality evolution.