A case study on 3D characterisation of pore structure in a tight sandstone gas reservoir: The Collyhurst Sandstone, East Irish Sea Basin, northern England
A case study on 3D characterisation of pore structure in a tight sandstone gas reservoir: The Collyhurst Sandstone, East Irish Sea Basin, northern England
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DOI：
10.1016/j.jngse.2019.102917
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发表时间：
2019-08-01
影响因子：
--
通讯作者：
Ma, Lin
中科院分区：
文献类型：
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作者：
Oluwadebi, Ayomiposi G.;Taylor, Kevin G.;Ma, Lin
致密气藏的孔隙系统控制着流动能力、可采孔隙体积、油气流动速度和储量等重要参数，这些参数的描述和量化很复杂。详细了解致密气藏三维孔隙结构对预测致密气藏产能至关重要。这项研究调查了英格兰北部致密气藏Collyhurst砂岩地层砂岩样品的孔隙结构。使用X射线计算机断层扫描(XCT)对孔系统(孔大小、形状、几何形状和连通性)进行量化。识别出三种类型的孔隙：位于碎屑颗粒和/或自生矿物交界处的粒间孔，位于碎屑矿物颗粒内的粒内孔，以及作为胶结相(自生矿物)内孔的水泥内孔。第一种类型为原生孔隙，后两种为次生孔隙。应用中心线树和孔隙网络模型(PNM)算法进行孔隙网络分析，估计孔隙度。通过实验室实验测量验证了基于图像的孔隙率值，3D图像估计的体积孔隙率为3.1%，而实验室实验记录的孔隙度为4.6%。研究砂岩孔隙类型的空间量化和孔隙连通性的分析提高了对天然气流动行为和天然气储存的理解。此外，研究结果对致密气藏渗透率和多相渗流特性的预测具有一定的参考价值。
Pore systems of tight-gas reservoirs control important parameters such as flow capacity, producible pore volumes, hydrocarbon flow rates and storage which are complex to characterise and to quantify. Detailed understanding of 3D pore structure is vital in predicting tight-gas reservoir productivity. This study investigates the pore architecture of a sandstone sample from Collyhurst Sandstone Formation, northern England, a tight gas reservoir. X-ray Computed Tomography (XCT) was employed to quantify the pore system (pore size, shape, geometry, and connectivity). Three types of pores were identified: inter-grain pores which are at the boundary of detrital grains and/or authigenic minerals, intra-grains pores which are pores within the detrital mineral grains, and intra-cement pores which are pores within the cement phase (authigenic minerals). The first pore type is primary in origin, whereas the latter two are secondary pores. A centerline tree and a pore network model (PNM) algorithm were applied for pore network analysis and a porosity value was estimated. The image-based porosity value was validated with laboratory experimental measurement 3D image estimates 3.1% volume porosity, while 4.6% was recorded from the laboratory experiment. Spatial quantification of pore types and analysis of pore connectivity of the studied sandstone improves understanding on gas flow behaviour and gas storage. Furthermore, the results are useful in predicting permeability and multi-flow phase properties in a tight gas reservoir.