Application Of X-ray Fluorescence Element Logging Technology In Kuqa Depression, Tarim Basin

In the process of oil and gas exploration and development,the most important work of conventional mudlogging is to accurately identify the lithology and to establish a precise stratigraphic profile on this basis.With the additional exploration and development in the Tarim Oilfield,the geological structure is becoming much more complex and the application of new drilling technology is more and more widely used,which has brought enormous challenges to the conventional mudlogging technology on identifying lithology,determinating the bottom depth of gypsum-salt rock layer and so on,and it is increasingly unable to meet the needs of the current exploration and development of Tarim Oilfield.The XRF element logging technology is a qualitative and quantitative analysis of the elements contained in the debris.This article is based on the strata features of Kumugeliemu group in central Kuche depression,choosing Si,Al,Fe,Ca,Mg,Na,K,S,P,Cl,Ba,Ti,Mn,V,Ni,Sr,Zr elements as the measurement and analysis elements of this project,these 17 elements include feature elements of the main minerals in the study area strata.In this study,a total of 30915 cutting samples from 35 wells on the Kelasu structural belt in Kuche depression were analyzed by X ray fluorescence,it is found that element content is closely related to lithology1)In view of the difficulties to identify the lithology under the new drilling technology,on the basis of the same kind lithology has similar XRF elements spectra characteristics,this article established the standard spectral library of main lithology such as sandstone,mudstone,carbonate rock,gypsum rock and salt rock,developed 4 kinds of lithology identification methods such as spectrum method,numerical method,curve method,quantitative method for the study area,and finally formed XRF element lithology logging method.According to the statistics of 10 wells application results,the coincidence rate of lithology identification is 85～100%,and the precision ratio of strata judgment is 80～98%.2)In view of the difficulties of the determination of the bottom depth of the gypsum-salt rock layer under complex geological conditions,this article through analyzing and studying Al,Mg,K,Cl,Ti,Sr,Zr elements.The results show that the elements features can reflect the variation characteristics of stratigraphic sedimentary environment,which developed the XRF element logging determination the bottom of the gypsum-salt rock layer technology.Using the element marker layer(abnormally high value segment of the Sr and Zr elements)to early warming salt bottom for horizontal comparison,and the elements characteristics(Mg,Cl element content)and chart(Mg-K-Ti triangle chart and Mg/Al-K/Cl intersection chart)are used to distinguish mudstone between salt and salt bottom.This technology is applied to 8 wells,and the success rate of 100%.Research results have been widely used in wells,the results show that XRF element logging technology can accurately identify lithology,confirm the feasibility and dependability of XRF element logging determination the bottom of the gypsum-salt rock layer technology,and solved the difficulties of conventional mudlogging technology in the current oil and gas exploration and development.