柴达木盆地南翼山油田卤水的水化学特征和U、S同位素组成及成因探讨  

Chemical U and S Isotopic Compositions and Genesis of Oilfield Brine in Nanyishan,Qaidam Basin,Northwestern China

作　　者：秦成功 许建新[1,2] 韩积斌 韩光[4] 赵为永 高雪峰 刘久波 QIN Chenggong;XU Jianxin;HAN Jibin;HAN Guang;ZHAO Weiyong;GAO Xuefeng;LIU Jiubo(Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resouces,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining,810008,China;Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes,Xining,810008,China;University of Chinese Academy of Sciences,Beijing,100049,China;Qinghai Qaidam Survey Institute of Comprehensive Geology and Mineral,Golmud 816000,China;Research Institute of Exploration and Development,Qinghai Oilfield Company,PetroChina Dunhuang,736202,China;Exploration Enterprise Department of Qinghai Oilfield Company,PetroChina,Dunhuang,736202,China)

机构地区：[1]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,青海西宁810008 [2]青海省盐湖地质与环境重点实验室,青海西宁810008 [3]中国科学院大学,北京100049 [4]青海省柴达木综合地质矿产勘查院,青海格尔木816000 [5]中国石油青海油田分公司勘探开发研究院,甘肃敦煌736202 [6]中国石油青海油田分公司勘探事业部,甘肃敦煌736202

出　　处：《盐湖研究》2024年第3期40-52,共13页Journal of Salt Lake Research

基　　金：第二次青藏高原综合考察项目(2019QZKK0805)。

摘　　要：南翼山油田卤水为多种资源共存的液体矿床,但至今尚未开发利用。本文首次利用(^(234)U/^(238)U)并结合南翼山油田卤水的水化学组成及S同位素数据,分析了沉积期后油田卤水水化学组成的变化,探讨了其变质过程。油田卤水的SO_(4)^(2-)和U含量分别为0.08~2.24 g/L和1.41~5.38μg/L,相对于石盐不饱和的大浪滩晶间卤水和石盐饱和的尕斯库勒盐湖卤水,油田卤水的SO_(4)^(2-)和U含量很低。油田卤水的δ^(34)S为53.59‰~58.46‰,明显较高,(^(234)U/^(238)U)为1.07~1.14,234U相对过剩。SO_(4)^(2-)的细菌和有机质还原是引起油田卤水变质、SO_(4)^(2-)含量大幅度减小和δ34S明显增大的主要因素。SO_(4)^(2-)还原过程中产生的H2S又促进了U的还原,从而使油田卤水的U含量减小和(^(234)U/^(238)U)增大。地表水和水岩反应对油田卤水的影响很小。这种地球化学条件不利于U向油田卤水中富集。南翼山油田卤水是硫酸盐型古盐湖卤水埋藏之后,经过变质而形成的氯化物型卤水。The oilfield brine in Nanyishan,contains multiple resource elements,but has not been ex-ploited.Using(^(234)U/^(238)U)firstly,and with the chemical compositions and S isotopic compositions,this pa-per studied the postdepositional change of the chemical compositions and the transformation of the oilfield brine in Nanyishan.The contents of SO_(4)^(2-)and U,0.08~2.24 g/L and 1.41~5.38μg/Lrespectively,are es-pecially lower in the oilfield brine,compared with the intercrystalline brine unsaturated with halite in Dalangtan and the salt lake brine saturated with halite in Gas Hure.The values ofδ34S,53.59‰~58.46‰,are high,and(^(234)U/^(238)U)Values change from 1.07 to 1.14 exhibiting the excess of 234U,in the oilfield brine.Reduction of SO_(4)^(2-),induced by anaerobic bacteria and organic matters,resulted in the transformation,de-creases of SO_(4)^(2-)contents,and increases ofδ34S,and sulphureted hydrogen produced during SO_(4)^(2-)reduction advanced the U reduction,leading decreases of U contents and increases of(^(234)U/^(238)U).The surface waters and water rock reactions had little effects on the chemical compositions,δ34S and(^(234)U/^(238)U)in the oilfield brine.In this situation,U is unable to enriched in the oilfield brine.The chloride-type oilfield brine in Nany-ishan had transformed from the sulfide-type brine in ancient salt lake after buried.

关 键 词：油田卤水 硫同位素 铀同位素 变质作用 南翼山构造区 

分 类 号：P641.464[天文地球—地质矿产勘探]