准噶尔盆地西北缘地层水化学特征及与油气保存关系

准噶尔盆地西北缘油气富集，油水关系复杂。基于研究区大量地层水化学数据，分析了石炭系—白垩系各含油层系地层水化学垂向、平面分布特征，并结合地质背景，对红山嘴油田进行解剖，探讨了地层水化学特征与油气保存之间的关系。研究区纵向上从深到浅、地层由老到新，地层水矿化度逐渐减小；平面上，石炭系—白垩系，地层水矿化度高值区呈现从西北缘逐渐往盆地内部迁移的趋势。盆缘地区或克—乌断裂上盘等地区受地表水或大气水下渗淋滤影响较大，地层水处于自由交替循环带，分布低矿化度、低氯离子浓度的Na₂SO₄型或NaHCO₃型水，地层封闭性较差，通常形成稠油；往盆地内部或克—乌断裂下盘等地区，地层水处于交替停滞带或阻滞带，浓缩程度高，主要分布高矿化度、高氯离子浓度CaCl₂型水，地层封闭性好，形成保存较好的中—轻质油。 

Chemical characteristics of formation water and the relationship with oil and gas preservation on northwestern margin of Junggar Basin

The northwestern margin of the Junggar Basin is rich in oil and gas, and the relationship between oil and water is complicated. A large amount of formation water data was used to examine the vertical and lateral distribution of the water chemistry in oil-bearing strata from the Carboniferous to the Cretaceous. Combined with the geological background, the Hongshanzui Oilfield was dissected and the relationship between the chemical characteristics of formation water and the preservation of oil and gas is discussed. The results show that the formation water salinity decreases gradually when the burial depth varies from deep to shallow layers and the stratigraphic age varies from old to new. From the Carboniferous to the Cretaceous, the high salinity area of the formation water gradually migrates from the northwestern margin to the interior of the basin. The margin of the basin or the Ke-Wu fracture hanging wall is greatly affected by the infiltration and leaching of surface water or atmospheric water. The formation water is in a free alternating circulation zone, with low salinity, low chloride ion concentration Na₂SO₄ type or NaHCO₃ type water. The formation is poorly sealed, and heavy oil is usually formed. To the interior of the basin or the Ke-Wu fracture footwall, the formation water is in an alternating or stable stagnation zone, with a high degree of concentration. There mainly exists high salinity and high chloride ion concentration CaCl₂ type water. The formation has good sealing properties and forms well-preserved medium-light oil.