杭锦旗地区上古生界地层水成因

Origin of Formation Water of Upper Paleozoic in Hangjinqi Area in Ordos Basin

鄂尔多斯盆地北部杭锦旗地区上古生界地层水总矿化度为13 831～89 445 mg/l,平均47 565.81 mg/l,属于盐水和卤水的范畴。pH值4.37～7.3,为弱酸性。地层水基本为CaCl2型水。泊尔江海子断裂带的地温梯度是最高的,断裂南部次之,断裂北部最低。泊尔江海子断裂附近地层水矿化度、pH值及地温梯度等出现异常,研究认为,造成断裂带地层水异常是由于混合作用,断裂带以外主要的流体-岩石相互反应是斜长石的钠长石化过程。

The total salinity of formation water of Upper Paleozoic in Hangjinqi area in northern Ordos basin ranges from 2 333.55 mg/L to 89 445 mg/L, averaging 47 565.81 mg/L. It belongs to the category of brine water and bittern, with pH value of 4.37-7.3 and mild acid property. The type of formation water is of CaCl2 one. The geothermal gradient in Boerjianghaizi fault belt is the highest, in the south part of it is the next place, and in the north part is the lowest. The formation water salinity, pH value and geothermal gradient near the belt are abnormal due to mixing process according to this study. The interaction between the fluids and the rocks assumes the process of albitization in plagioclase.