柴达木盆地马海盐湖储卤层渗透特征及卤水富集机制

通过野外抽水试验方法，确定了柴达木盆地马海盐湖储卤层渗透系数，并结合地下卤水赋存特征与沉积环境对其渗透性能进行分析。结果表明：本地区石盐层大多不纯，石盐晶体内包裹有泥、砂，且晶体间也有泥、砂充填。在石盐沉积期间，由于受到洪水与间歇性河流影响，导致地质环境演化过程中沉积形成的储卤层渗透性能在各处相差较大，区域地下卤水的连通性相对较弱。根据试验开采区27口开采井钻孔资料和地下卤水监测数据，进行了储卤层差异性分类，将钻孔所揭露储卤层划分为3种类型，不同类型储卤层卤水富集性能具有较大差异，表现为渗透系数和单井涌水量在平面分布上的较大数值差距。通过对钻孔岩心岩性、孔隙特征及补给条件等方面进行分析，得出卤水富集性能强的基本条件：储卤层具备天然良好的颗粒骨架和稳定的卤水补给来源与通道。依据储卤层渗透性能和卤水富集规律，将马海盐湖试验开采区划分出不同地下卤水富集区段。

Permeability and Brine Enrichment Mechanism of Brine Reservoir in the Mahai Salt Lake,Qaidam Basin

The permeability coefficient of brine reservoir in the Mahai Salt Lake of Qaidam Basin was determined by field pumping test, and its permeability was analyzed by the occurrence characteristics and sedimentary environment of underground brine. The results showed that most of the rock salt layers in this area are impure, the rock salt crystals are wrapped with mud and sand, and the crystals are also filled with mud and sand. During the period of rock salt deposition, the permeability of the brine reservoirs formed during the evolution of the geological environment varied considerably due to the influence of floods and intermittent rivers, and the connectivity of the regional subsurface brine was weak. According to the drilling data of 27 mining wells and the monitoring data of underground brine in the experimental mining area, the brine reservoir was classified differentially. The brine reservoirs exposed by the drilling were divided into three types. The brine enrichment performance of different types of brine reservoirs is quite different. Through the analysis of the lithology, pore characteristics and supply conditions of borehole cores, the basic conditions for strong brine enrichment performance were obtained: The brine reservoir has a natural good particle skeleton and a stable brine supply source and channel. According to the permeability of brine reservoir and the law of brine enrichment, the experimental mining area of the Mahai Salt Lake was divided into different underground brine enrichment sections.