金坛盐穴储气库微渗层分布规律及物理特性研究

金坛储气库茅兴矿区在建库过程中钻遇一微渗层，该微渗层具有一定的漏失特性且广泛、连续分布在工区内，给井位部署及后期建库带来了较大挑战。为加深对该微渗层的认识、降低其对建库的不利影响，对该微渗层的分布特征、岩心特征、成分、渗透性等物理性质进行了研究。三维地震勘探和钻井施工表明，该微渗层位于造腔盐层段内，距离盐顶平均距离约20 m，平均厚度约为0.8 m且在该工区内均有分布。取样结果表明:该微渗层主要成分为泥岩，且大量分布微裂缝，以纵向微裂缝为主，裂缝密度10~20条/m，裂缝长度10~200 mm；纵向微裂缝被盐硝等物质充填，充填物处于未压实或欠压实以及裂隙未完全被结晶充填状态，是影响该微渗层密闭性的主要因素；试验测得微渗层孔隙度为7.52%~14.18%，平均值为11.74%，渗透率为0.11×10?3~21.2×10?3 μm2，平均值为8.155×10?3 μm2，是造成漏失的主要原因。研究结果可为该区域后期布井和完井结构优化提供基础参数和技术参考。

Study on the distribution laws and physical properties of the micro-infiltrated layer in the Jintan salt-cavern gas storage

In the process of storage construction in Maoxing field of Jintan gas storage, a micro-infiltrated layer is encountered, which has certain characteristics of filtration and is distributed extensively and continuously in the working area, so as to bring greater challenges to well deployment and later storage construction. In order to understand this micro-infiltrated layer further and reduce its adverse impact on storage construction, this paper studied its physical properties, including distribution characteristics, core characteristics, compositions and permeability. 3D seismic exploration and drilling construction show that this micro-infiltrated layer is located in the salt interval of cavity construction and it is distributed all over the working area. And its distance from the salt top averages about 20 m and its average thickness is 0.8 m. Sampling analysis results show that this micro-infiltrated layers is mainly composed of mudstone. There are a large number of micro-fractures, which are dominated by vertical micro-fractures. The fracture density is 10-20/m and the fracture length is 10-200 mm. The vertical micro-fractures are filled with salt and nitrate. And the fillings are in the state of uncompaction or undercompaction and the fractures are not completely filled with crystals, which are the main factors influencing the sealing capacity of the micro-infiltrated layer. The tested porosity of the micro-infiltrated layer is 7.52%-14.18%, averaging 11.74%, and its permeability is (0.11-21.2)×10?3 μm2, averaging 8.155×10?3 μm2, which are the main reasons for the filtration. The research results can provide the basic parameters and technical references for the later well deployment and completion structure optimization in this area.