油页岩原位开采对地下水环境影响研究

In-situ mining of oil shale has become one of the research hotpots at present dur to its low production cost and less impact of pollution on environment. The technique for in-situ mining of oil shale is that the underground strata of oil shale is first heaten directly, and promoted to pyrolysis underground to become oil gas, and finally the oil gas is pumped out from production wells. In-situ mining of oil shale also has some influence on environment, and its influence on groundwater environment is very complicated. So in the representative area of oil shale mining Jiln University, The research on the influence of in-situ oil shale mining on groundwater environment is carried out. .The main research methods include field investigation on practical geology and hydrgeology, indoor experiment and computer simulation. The research focuses mainly on the creep and moving deformations of overlying formations caused by Pintsch process of oil shale, the impact of freezing wall in the pyrogenous mining areas on the hydrogeological properties and on the environment of groundwater storage. The change of aquifer field, groundwater seepage field，hydrogeochemical field and temperature field caused by in-situ mining of oil shale is simulated and forecasted by indoor experiment and by establishing numerical simulation model of groundwater and its environment. The change of groundwater environment probably caused is analyzed. The impact of in-situ oil shale on storage the environment of groundwater is carried out according to the stability of surrounding rock masses caused by high-temperature pyrolysis of oil shale and according to the corresponding creeping deformation and moving deformation of overlying strata. Groundwater numerical simulation model is set up to simulate and forecast the groundwater flow field, groundwater temperature and groundwater chemical environment influenced by freezing wall for oil shale mining. The produced change of groundwater resources and evolution of groundwater environment is analyzed and studied. The evolutionary process and law of groundwater environment is forecasted during ecological restoration after in-situ mining of oil shale is terminated. The research results will provide theoretical basis for the further perfection of in-situ mining process and technology of oil shale.

油页岩原位开采因其生产成本低，对环境的污染小成为当今研究的热点，油页岩原位开采技术是通过直接给地下油页岩加热，使其在地下裂解，生成油气，然后通过生产井把油气开采出来。但油页岩原位开采对环境也有一定的影响，对地下水环境的影响就更为复杂。为此在吉林大学油页岩原位开采示范区，针对油页岩原位开采可能对地下水产生的影响进行研究。.以野外地质、水文地质条件为基础，以室内实验和计算机模拟技术为研究手段，针对高温裂解油页岩可能引起上覆地层的蠕动变形、移动变形和开采干馏区冷冻墙可能对水文地质属性和对地下水赋存环境的影响进行研究。通过室内实验和建立地下水及其赋存环境的数值模型对油页岩原位开采造成的含水层、地下水流场、化学场和温度场变化进行模拟和预测，分析可能地下水环境变化；预测油页岩原位开采恢复期间地下水的演化规律，提出合理的地下水恢复方案，为油页岩原位开采技术及工艺完善提出理论基础依据。

以东北地区农安、扶余、桦甸、抚顺、梅河口五个地区油页岩为研究对象，主要研究内容包括高温裂解油页岩对水文地质属性、地下水赋存环境的影响，上覆地层变形随时间的逐步演化过程，油页岩原位开采导致地下水赋存条件演化及其水文地质属性的扰动机理，高温裂解油页岩对地下水化学场的影响，冷冻墙、化学帷幕等对地下水流场、地下水温度和地下水化学场的影响，油页岩原位开采引起的地下水环境系统的扰动问题，采用室内实验和计算机模型等手段研究地下水环境系统的扰动机理。项目进行过程中获取了大量的油页岩测试及实验数据，重要成果包括揭示了油页岩原位开采对油页岩热解过程及水、油、气、残渣向环境中的释放量、地层孔隙度、渗透性、油页岩微观形态和油页岩矿物成分的影响，油页岩原位开采产生的污染物主要有C7—C26烷烃、烯烃、苯系物、萘、醇等；油页岩原位开采对地下水化学组分的影响主要表现为烃类物质，次为苯系物、吡啶、喹啉类、酚类、苯胺、萘酚；油页岩开采冷冻墙对地下水影响，利用实验数据分析冷冻场的变化，利用函数解析的方式来揭示了冻结区域和未冻结区域的温度变化过程；水岩相互作用试验结果揭示了水溶液中pH变化规律、油页岩中酚类、苯系物、有机碳（TOC）、总石油烃（TPH）等有机物的释放规律、油页岩中铅、铬、锌、铁、铜等重金属的浸出规律及迁移机理；建立了油页岩原位开采实验模拟模型，对农安油页岩原位开采区和桦甸地区油页岩开采进行了模拟实验，同时开展了油页岩原位开采试验数值模拟，揭示了热解过程中应力场变化规律；构建了原位开采区的地下水环境系统分析理论体系，通过油页岩原位开采冷冻墙的建立对地下水温度场及流场影响模拟研究，定量分析了油页岩原位开采对上覆地层的移动变形的影响。本项目的科学意义在于揭示了油页岩原位开采对地下水环境的影响机理，为油页岩原位开采和防治环境影响提供了科学依据。