储油环境下硬石膏围岩时效弱化机理与洞室群长期稳定性研究

Deep underground space formed by mining is a valuable space resource. Oil reservoirs built under those anhydrite goaf with good stability and sealability provide a new way for the underground energy storage. Under the environment of oil, surrounding rock of anhydrite usuallly interacts with storage medium in the form of water-rock/oil-rock reaction. Under the background of the project carried out in anhydrite mine oil reservoirs in Hanshan, Anhui Province, this project aims to reveal the process of time evolution of the deformation mechanism and the strengh mechanism of anhydrite surrounding rock,as well as to predict long-term stability of oil storage cavern groups, then some problems are to be solved. Above all, engineering geological characteristics and the damage law of mining room deformation in deep anhydrite rock layers are proposed, possible buckling modes after storage is predicted.The second, physical and chemical characteristics of the process of water - rock/oil - rock reaction in anhydrite rock are studied in multiple scales, the aging weakening effects that brought to the physical and mechanical properties of anhydrite rock mass by this process is revealed.The third, long term stength attenuation of anhydrite rock under the inflence of both water-rock/oil-rock reaction and stress is studied, theoretical formula and creep constitutive model based on rock stengh attenuation over time are established.The last, the evaluation method of long term stength of anhydrite rock groups under the environment of oil is proposed,which provides a scientific basis to predict long term stability and to optimize the underground structure of anhydrite oil reservoirs.On the other hand,the research results will also provide the reference for nuclear waste disposal and CO2 geological storage carried on in the anhydrite rock layers.

深部采矿形成的地下空间是一种宝贵的资源，利用自稳性好、密封程度高的硬石膏采空区建造石油储库，为地下能源储备提供了一种新的途径。储油环境下硬石膏围岩将与存储介质发生复杂的水-岩/油-岩作用，项目以揭示这一过程中硬石膏围岩强度与变形的时效演化机制，预测服役期储油洞室群长期稳定性为研究目标，以安徽含山石膏矿井储油为工程背景，研究深部硬石膏岩层工程地质特性及采房变形破坏规律，预判储油后可能的失稳模式；研究多尺度下硬石膏水-岩/油-岩作用过程的物理化学特征，揭示这一过程对硬石膏岩体物理力学性质的时效弱化机制；研究水-岩/油-岩与应力耦合作用下硬石膏长期强度衰减规律，建立岩石强度随作用时间衰减的理论公式及蠕变本构模型；最后融合上述成果提出考虑储油环境的洞室群长期稳定性评判方法，为服役期硬石膏储油库长期稳定性预测及洞库优化提供科学依据。研究成果还可为利用硬石膏岩层进行核废处置及二氧化碳地质封存提供参考。

基金项目依托安徽恒泰硬石膏矿，结合系统的室内试验和现场调研，分析了岩石矿物成分、细观尺度上的孔隙分布特征以及宏观尺度上的表观密度等参数，获取了硬石膏岩石和岩体的物理力学特征参数；考虑岩体拉压特性差异，开发了考虑硬石膏岩石拉压特性差异的弹塑性本构模型；基于单元安全系数法，定量分析了硬石膏采空区现状条件下（非储油）的稳定性；开展加压环境下硬石膏岩石的长期浸水、浸油试验，揭示了水、油与硬石膏岩石的长期作用机制，评价了水、油对硬石膏物理力学特性的影响及硬石膏岩石对原油品质的影响；应用室内试验和数值计算手段，揭示了天然条件和储油条件下硬石膏采空区的长期变形和有效地下储存空间损失规律，研究了其作为地下原油储存空间的长期稳定性问题。通过该研究，科学系统地解决了硬石膏采空区作为地下原油储存空间的基础科学问题，为硬石膏采空区这一潜在地下空间资源的有效利用提供了理论支撑，具有重大的理论价值和实践意义。