柴达木盆地西部古近系和新近系油田卤水资源水化学特征及化学演化

在柴达木盆地西部一些背斜构造单元的古近系-新近系中,赋存储量巨大的油田卤水，有望成为第四系盐湖卤水的后续利用资源。通过对小梁山、南翼山、油泉子、开特米里克、油墩子、油砂山等典型构造区石油钻孔自喷的油田卤水以及地表盐湖卤水、晶间卤水取样分析，讨论了其水化学特征及资源分布，重点通过与海水、青海湖水蒸发曲线对比，分析了油田卤水的化学演化特征。结果表明，油田卤水中K、B、Li资源远超工业开采品位，Br、Sr等也达到工业开采品位，有优越的高品位综合开发利用前景；油田卤水资源元素富集规律表现为平面上以中部南翼山背斜最为富集，向北、向南相对降低，垂向上深部油田卤水比浅层晶间卤水、湖表卤水资源元素相对更为富集；油田卤水的化学演化主要受控于水岩反应、深部水的混合以及蒸发浓缩和盐岩的溶解作用，这些作用为卤水分异演化、富集成矿提供了良好的地球化学条件。

Hydrochemistry characteristics and chemical evolution of oilfield brines of the Paleogene and Neogene in western Qaidam Basin

The oilfield brines with a great quantity of reserves exist in the Paleogene-Neogene in some anticlines of the western Qaidam Basin. They are expected to be the resources to sustain the Quaternary salt lake brines. By the analyses of the oilfield brines samples collected from the boreholes in the typical tectonic areas including Xiaoliangshan, Youquanzi, Kaitemilike, Youdunzi, and Youshashan and the saline lake brine samples, and inter-crystal brine samples on earth, the hydrochemistry characteristics and resource distribution are discussed. Compared with the evaporate curves of the marine water and the Qinghai Lake water, the chemical evolution of the oilfield brines is analyzed. The results indicate that the resources of K, B,Li are much higher than the industrial grade. Br and Sr also reach the industrial grade. Thus the exploration and utilization prospect of oilfield brines is very good. The planar distribution of oilfield brines is characterized by most enriching in the central Nanyishan anticline and reducing toward the north and the south. Vertically, the oilfield brines are more likely to enrich in the deep interval than in the shallow interval inter-crystal brines and the lacustrine water. The chemical evolution of oilfield brines is dominated by water-rock reaction, mixing, evaporation and condensation of deep water and salt rock dissolution. These processes provide good geochemical conditions for the brines evolution and accumulation.