塔里木盆地塔中低凸起地层水化学特征对不整合的响应

Response of formation water chemistry to unconformities in Tazhong low uplift of Tarim Basin

对塔中低凸起地层水化学特征与不整合之间关系的研究结果表明,地层水化学特征对不整合具有很好的响应。在遭受强烈抬升和剥蚀、之间形成不整合的奥陶系和志留系,以及紧靠不整合面附近的石炭系CⅢ油组,其地层水具有矿化度、Cl-含量、K++Na+含量和r(Cl-Na)/rMg值相对较小,而HCO3-含量、rNa/rCl值和rSO42-×100/rCl值相对较大的特点,反映出地质历史时期大气降水的影响。在志留系与石炭系之间以及志留系与奥陶系之间的不整合面附近,地层水的矿化度、r(Cl-Na)/rMg值和B3+含量变小,而rNa/rCl值和rSO24-×100/rCl值变大,具有典型的遭受大气淋滤的地层水化学基本特征。

The studies of the relationship between formation water chemistry and unconformities in the Tazhong low uplift of the Tarim Basin indicate that formation water chemistry has an obvious response to unconformities. The Ordovician and Silurian, along whose surface the unconformity was developed after intense uplift and erosion, and the Carboniferous CⅢ petroliferous interval adjacent to the unconformity are characterized by relative low formation water TDS, contents of Cl^- and K ^＋＋ Na^＋, r（Cl-Na）/rMg, and relative high values of rNa/rCl, rSO4^2- × 100/rCl, high content of HCO3^- These results show the influence of precipitation during the geologic history. Along the unconformities between the Silurian and Carboniferous, the Silurian and Ordovieian, the values of formation water TDS, r（Cl-Na）/rMg and content of B^3＋ reduce,while the values of rSO4^2- × 100/rCl increase which are the characteristic of formation water influenced by mefeoric water leaching.