青海聚乎更水合物赋存区岩心微观孔隙、裂隙的微CT图像表征
CT Image Characterization of Pores and Fissures in Rock Core from Juhugeng Gas Hydrate Area in Qinghai

摘要： 孔隙和裂隙的微观结构是影响岩石声波速度、渗透率等物性参数的重要因素，这些物性参数是冻土区天然气水合物成藏规律研究和资源勘探的重要 依据。针对青海聚乎更钻探区钻井岩心，采用微米级计算机断层扫描技术(微CT)对岩心内部的微观孔隙和裂隙进行了形态表征和定量分析。结果表明：泥岩样品中的裂隙较为丰富且连通性较好，裂隙宽度多为100~200 μm；而砂岩样品中孔隙分布较为分散且少有显著的连通喉道，数量上以体积小于0.1 mm3的微孔隙为主；通过三维图像体素统计法估算了孔隙和裂隙相对整个岩心的体积含量，其中砂岩样品的孔(裂)隙度为2.36%~2.89%，泥岩样品的孔(裂)隙度为1.04%~3.64%。
Abstract: Microstructure of pores and fissures is an important factor which influences the rock physical parameters such as acoustic velocity, permeability. These physical parameters are the important foundation for the gas hydrate accumulation and exploration in permafrost. The rock core samples recovered from Juhugeng district in Qinghai Province were studied in this paper. The pores and fissures of these samples were detected by the micro-focus computer tomography (micro CT). The results show that fissures widely exist in mudstone in good connectivity with the widths between 100 to 200 μm. However, pores are distributed dispersedly and there are poorly connected throats in sandstone with volumes of most pores lower than 0.1 mm3. The porosities of cores are estimated to be 2.36%-2.89% (sandstone samples) and 1.04%-3.64% (mudstone samples) respectively by the method of counting the voxel of 3D gray images