锂元素及其同位素对南翼山油田卤水形成演化的指示意义

Geochemistry of Li and Its Isotope:Implications for Origin and Evolution of Oilfield Water in Nanyishan Tectonic Area,Qaidam Basin,Northwest China

中文关键词:  油田卤水  锂同位素  水岩反应  地球化学  南翼山构造区

英文关键词:Oilfield water  Lithium isotope  Water\|rock reaction  Geochemistry  Nanyishan tectonic area

中文摘要:

      南翼山油田卤水以高钙富锂等元素为特征,是柴达木盆地研究程度较高的油田卤水之一。根据南翼山构造区及其周边地区油田卤水、盐湖卤水、河水和潜水等不同水体的水化学及岩层的地球化学和矿物特征,研究了湖水的蒸发浓缩对Li⁺的富集作用,探讨了水岩反应对油田卤水Li⁺含量和δ⁷Li的影响。结果表明,埋藏之前的蒸发浓缩是Li⁺含量和总固溶物增大的主要原因；水岩反应对Li⁺含量和δ⁷Li有影响,但不会引起明显变化。南翼山油田卤水主要来源于古盐湖卤水,演化过程中曾受到水岩反应的影响。

英文摘要:

      The oilfield water,in Nanyishan tectonic area,contains high level of lithium and calcium.It is one of the oilfield waters,in Qaidam basin,which has been studied in\|depth in recent years.According to the water chemical compositions and the Li isotopic compositions of the oilfield water in Nanyishan tectonic area and other waters(the brine in Gas Hure salt lake,the intercrystalline brine in Dalangtan playa,the river water in Aral and the well water in Mangya),and the geochemistry and mineral assemblages of different rocks,this paper studied the enrichment of Li⁺ in the brine during evaporation,and discussed the changes of Li⁺ contents and Li isotopic compositions in the oilfield water during postdepositional water\|rock reactions.The results showed that the evaporation of the brine in ancient salt lake primarily led to the increase of Li⁺ contents and TDS,and that postdepositional water\|rock reactions resulted indistinctively in changes of Li⁺ contents and Li isotopic compositions.The residual brine in ancient salt lake was the primary source of the oilfield water in Nanyishan tectonic area.During its postdepositional evolution,the oilfield water has been changed little by water\|rock reactions.