The Distribution Rules And Origin Of Salt Forming Elements Of The Tertiary Oil Field Brine In Western Qaidam Basin

The study covers the Sanhu area,Southwest,Northwest and the northern margin of Qaidam Basin.The K,B,Li,Br,I,Rb,Cs of the oil field water were tested and analysised to explore the distribution of salt formatting elements,the brine of Nanyishan and Eboliang was studied by evaporation to explore the availability.In order to analysis the origin,some of the samples of Nanyishan,Xianshuiquan,Youquanzi,Shizigou,Jiandingshan,Dafengshan were tested the boron and chlorine isotopes and all of the samples were tested trace metal elements,for example,Fe Zn Ni and so on.The result of salt forming elements distribution analysis showed that B,I,Br,Li are widely distributed,followed by K,Ru and Cs are poor.According to its concentration,B is the best,followed by Li and K is poor.It can be seen that the availability of B,Li,K are the highest,followed by Br and I Rb Cs are relatively poor;In terms of area,the mineralization degree and the contents of various ore-forming elements of the brine under western Qaidam is high,which is opposite in Sanhu and northern margin of Qaidam Basin.The best areas which contain high quality oil field water are Nanyishan and Shizigou,followed by Xianshuiquan and Zhahaquan.The brine in these areas not only has a comprehensive content of various kinds of ore-forming elements,but also has high content and high comprehensive utilization value.The usability evaluation is carried out by means of outdoor evaporation and indoor chemical analysis,phase diagram analysis,solid samples XRD,SEM-EDS analysis research and so on,the results shows that,We can get potassium products by evaporation from Nanyishan,where represented the western Qaidam Basin oil field water,then acidifing the brine to get borate products,finally adding soda ash to get lithium carbonate products.Eboliang,where represented the Sanhu area oil field water has low mineralization degree.After the pre evaporation and concentration we can deal it as Nanyishan oilfield water.All the brine has high comprehensive utilization value.We analysis the origin through the hydrochemical types of sample analysis,trace metal content and boron and chlorine isotopic analysis,the results show that the water chemistry type is calcium chloride dominated,indicating a deep environment,the isotope and trace metal content analysis show that,the causes mainly meteoric water mixed with deep material,in the formation process it dissolution salt in the stratum.