盐穴储库存储介质渗漏迁移评估与防控研究

During the long-time running of deep underground salt caverns, the leakage and migration of the storage medium is related to the salt sedimentary rhythm, formation fractures and operational parameters of the storage. The evaluation, prevention and control of the tightness of the salt cavern is a complicated and valuable technical issue. Relying the salt cavern gas storage in Jintan, Jiangsu, fundamental research of the evaluation, prevention and control of the leakage and migration of the storage medium is performed. The crystal-dissolving-recrystallization process of the brine in non-salt interlayers is researched. The erosion and sealing effect of the phase change on the micro-structure of salt and the tightness of the storage is explored. Aiming at the micro-seepage layer of Jintan salt mine, the feasibility of blockage by grouting is discussed. The diffusion rule and sealing mechanism of the grout in the seepage layer are revealed. The leakage and migration rule of oil and gas in the long-time running of salt cavern is simulated by the self-designed leakage simulation platform. The salt cavern tightness is evaluated by analyzing the leakage range and leakage rate. Field application is performed based on the theoretical results, to complete the evaluation, prevention and control system of the leakage and migration of the storage medium in salt cavern storage. The research provides the theory and technology supports for the safe long-time running of salt cavern storage in China. The construction of underground energy reservoirs will be well promoted.

深部地下盐穴储库长期运行过程中，其存储介质的渗漏迁移受到盐矿层沉积韵律、地层裂隙发育、储库运行参数等多方面因素影响，储库的密封性评估与防控是一个复杂但却十分重要的科技难题。项目拟依托江苏金坛盐穴储气库工程，开展盐穴储库存储介质渗漏迁移评估与防控应用基础研究。通过研究卤水在非盐类夹层中的结晶-溶解-再结晶的相变过程，明确其对岩石细微观结构的侵蚀弱化和结晶封堵作用；针对盐穴脖颈段漏失层开展注浆封堵可行性基础研究，揭示止漏浆液在泄漏岩层中的扩散规律及封堵机理；利用室内长岩心渗流模拟实验平台，研究储库长期运行过程中油气大范围渗漏运移规律，建立腔体密闭安全性评估的指标体系。综合上述成果，开展现场应用与验证，进一步完善形成盐穴储库存储介质水平向渗漏迁移评估与防控体系。项目研究将为我国盐穴储库的长期安全运行提供理论与技术支撑，有利于保障我国能源地下储备的顺利实施。

我国石油和天然气对外依存度高，全面发展大规模地下能源储备，特别是盐岩油气地下储备，是保障我国能源安全和经济稳定的重要举措。然而，相较于欧美地区海相沉积的盐丘有所不同，我国的盐岩储库地层绝大部分属于湖相沉积的层状盐岩，地质赋存条件复杂加上缺乏建库实践，导致在此类盐层中建造储库面临着一系列理论和技术上的难题，这其中最为重要且无法回避的问题便是层状盐岩储库在运行期间的密闭安全性评价。为此，自主研制了深部地层岩心侵蚀渗流实验平台，并开展了高地压条件下介质长距离渗流迁移试验研究，探明了储存介质的渗漏机理以及相应情况下泄漏量对储库的影响程度；通过深入分析试验结果，建立了盐岩储气库平面径向流下的渗漏范围和渗漏量定量分析理论模型，并通过渗流理论分别推导了天然气在地层中一维和二维轴对称渗流下的孔压分布函数；将室内研究与现场储库泄漏防控相结合，自行研制了微渗透岩石注浆封堵试验平台开展相关试验，对浆液在低渗透率岩石内渗流机理以及封堵成效进行了研究，成功应用于国内某储库脖颈段微渗漏地层的封堵治理。最后，提出了运营期间盐岩储气库密闭性定量评估的关键性指标参数，构建了盐岩储库运营期密闭性评估与泄漏防治体系。研究成果为我国层状盐岩储库的密闭性评价、泄漏监测和安全防控奠定了一定的理论与技术基础。