临断层盐穴储气库安全评价与设计控制

This project is carried out aiming at the key scientific issue in safety evaluation and design of salt cavern gas storage to a tectonic fault in the bedded salt rocks. Main research contents are as follows. Firstly, basing on the underground gas storage library projects at Jiangsu Jintan and Huaian, Hubei Qianjiang and Yingcheng salt mines, the strike-slip models used to depict the fault under different conditions are proposed. The 3D geomechanical model of caverns close to a fault is built up, and its reliability is proved by the physical model in the lab. Secondly, by using the methods of theory analysis, laboratory tests and numerical simulation comprehensively, the influences of a tectonic fault on the stress and deformation of adjacent cavern under water leaching and operation, and the effect of the failure of cavern to a fault on the other caverns are analyzed. The instability generation, development, and formation mechanism of the cavern adjacent a tectonic fault are explained in detail. Thirdly, the failure critical conditions of fault and cavern are proposed. The quantitative effect weights of different factors on the cavern safety are given. Eventually, a safety-forecast model and criterion of the cavern to a tectonic fault is expected to be established and the critical distance between cavern and a fault, cavern dimensions, and operating parameters, etc., are proposed, which will be tested and modified by engineering application. Research results of this project will provide theoretical basis in the safety assessment and forecast for the salt cavern to a tectonic fault, and also provide technical support for the implementation of underground gas storage strategy plans of China.

本项目紧紧围绕我国层状盐岩中临断层盐穴储气库安全评价和设计控制中的关键科学问题开展研究工作。主要研究内容为：以我国江苏金坛、淮安、湖北潜江及应城盐岩地下盐穴储气库群为示范工程，系统研究不同条件下地质断层破坏的粘-滑模型，建立临断层盐穴三维地质力学模型并利用室内物理模型实验进行验证。利用该模型研究盐穴中充满卤水和注采气工况下断层对相邻盐穴（群）围岩的应力、变形和地表沉降量影响规律，揭示临断层盐穴失稳和泄漏孕育、发展和形成机理。给出断层和盐穴失效的临界条件，量化不同参数对临断层盐穴安全性的影响权重。最终建立一套临断层盐穴安全性评价标标准，实现对盐穴与断层距离、盐穴尺寸和运行参数等的设计控制，并通过示范工程检验并修正提出模型的准确性。研究成果将为我国临断层盐穴安全评价和设计控制提供理论依据和技术支撑。

我国盐穴储气库建库目标区域内分布着大量的地质断层。由于地质断层强度低、渗透率大、孔隙度高，不能对天然气形成有效封堵，因此在前期盐穴储气库建设过程中盐穴与断层之间的距离取得较大，降低了盐岩地层的利用效率。如何降低盐穴与断层之间的距离又能确保盐穴储气库的安全是本项目主要研究目标。本项目紧紧围绕该研究目标，以江苏金坛盐穴储气库为依托，通过对现场地质条件调研和目标地层岩心的钻取，并结合已有地质断层破坏活化特征，建立了在盐穴建造及运行载荷扰动影响条件下地质断层破坏的粘-滑模型。通过对盐岩、泥岩夹层、泥岩盖层等岩石试样开展渗透性测试实验获得了它们的渗透率及其渗透规律，为准确描述卤水、天然气在断层诱导下发生渗透泄漏提供了基础数据。根据上述实验结果和金坛盐穴储气库建库目标地层的地质特征，建立了临近断层盐穴储气库的三维地质力学模型，对临近断层盐穴形状、尺寸和运行参数进行优化，同时对不同工况下临近断层盐穴储气库的安全进行评价，给出了临近断层盐穴储气库设计准则和建议参数，为金坛临近断层盐穴储气库设计提供了依据。研究成果在金坛盐穴储气库建设中得到应用，将盐穴与断层之间的安全距离从原设计的240m降低到160m。研究成果还可以用于临近断层的盐穴储油库、盐穴压气蓄能库等的优化设计。