The influence of sedimentary rock fabrics on subsurface fluid flow: origin of quartz cement distribution in sandstones

本研究旨在探讨沉积岩结构对流体流动的影响。沉积岩不是规则的颗粒或晶体团块。相反，它们是不均匀的，在多个尺度上包含各种结构，包括颗粒的微观排列和厘米到米尺度的层，构成了岩石的结构。颗粒之间充满流体的孔隙空间的几何形状同样是不均匀的，因此岩石内的流体不会在所有方向上均匀流动。例如，流经沉积层的流体通常比沿着沉积层流动的流体少，但人们并不总是清楚为什么会这样。通过应用显微镜图像分析和统计技术对不同方向的岩石剖面进行定量描述孔隙和颗粒结构。在这些方向上也进行了流量测量，然后可以将流动的质量或岩石的渗透性与岩石结构联系起来。研究的重点将放在砂岩上，这些砂岩在不同程度上被石英胶结，石英在颗粒周围结晶，在这个过程中填满了以前开放的孔隙。由于孔隙空间可能被流体（油、气、水）占据，石英胶结物的分布对于建立地下流体储层的概念和应用模型具有重要意义。该研究对于进一步了解地下流体流动的控制机制，如水在含水层中的流动、富矿质溶液在沉积岩中的运移、油气在油气藏中的运移等，具有重要的基础意义。特别是石英水泥被认为是砂岩油气藏（包括加拿大的许多油气田）中最有效的替代孔隙空间的水泥，增加对其分布的了解直接适用于提高这些资源的利用和管理。

The proposed research aims to investigate the influence of the structures in sedimentary rocks on fluid flow. Sedimentary rocks are not regular masses of grains or crystals. Instead, they are heterogeneous, containing a variety of structures at multiple scales, including the microscopic alignment of grains and cm- to metre-scale layers, making-up the fabric of rocks. The geometry of fluid-filled pore spaces in between the grains is similarly heterogeneous, and therefore fluids within the rocks will not flow equally in all directions. As an example, fluid flow across sedimentary layers is typically less than flow along layers, but it is not always clear why this is so. The pore and grain fabric is described quantitatively by applying microscope image analysis and statistical techniques to sections of rock that are oriented in various directions. Flow measurements in these directions are also made, and the quality of flow, or permeability of the rock, can then be related to the rock fabric. The focus will be on sandstones that are cemented to varying degrees by quartz that crystallizes around grains, filling formerly open pores in the process. Since that pore space could otherwise be occupied by fluids (oil, gas, water), the distribution of quartz cement is of great interest to build conceptual and applied models of subsurface fluid reservoirs. This research is of fundamental importance to learn more about the controls on fluid flow in the subsurface, such as the flow of water through aquifer layers, the migration through sedimentary rocks of mineral-rich solutions, or how oil and gas is transported in hydrocarbon reservoirs. Quartz cement in particular is considered to be the most effective cement replacing pore space in sandstone hydrocarbon reservoirs (including many oil&gas fields in Canada), and increased understanding of its distribution is directly applicable to improve the utilization and management of these resources.