Research And Application Of Natural Gamma-ray Spectrometry Logging Data In Jilin Oilfield

In order to further study the characteristics of Jilin Oilfield reservoir andprovide some basic parameters for the oilfield development and production,sogetting lithology, types and contents of clay mineral of reservoir is greatsignificant for the Jilin Oilfield's oil exploration, development and production.The natural gamma-ray spectrometry logging is one geophysicalexploration method. That needs to survey nature existing radionuclide in strata,which can survey the five parameters, including total intensity of gamma rayU,Th and K, but also contents of U,Th,K. Contents of U,Th and K mayinstruct many characteristics of reservoir, such as clay minerals, lithology andso on. Research of clay minerals is advantageous to protect oil layer, enhanceoutput of crude oil and final recovery factor. Clay minerals in rocks nearlyaffect all logging reading data. So related characteristic of clay minerals mustbe identified and researched in the actual production process. Thedetermination of stratum lithology is also an extremely important foundationwork, because it provides important information for petroleum exploration anddevelopment. The basis of natural gamma-ray Spectrometry loggingrecognition lithology is different content of U, Th, K in different rocks or bigdifferences of ratio among them. We can determine type of rocks according tothe information, which provides the basis for appraising source bed, oil reservoir and cap rock..Based on above reasons, in the thesis, the author has conducted research ofthe gamma-ray Spectrometry in view of oil production area in Jilin oil field.The goal is to provide important instruction information for logginginterpretation of the area, so as to carry on reservoir appraisal well. Moreover,to take one kind of application example of natural gamma -ray Spectrometrylogging data provides reference for the further research.In view of the specific issue of Jilin Oilfield, the following appliedresearch has been done in this thesis, and certain results have been achieved.(1),Starting with the traditional clay mineral analysis chart(Schlumberger chart), we have analyzed the principle of clay mineralsidentification in the chart and problems existed in identification process.Through research on traditional chart board, we can get that information:Traditional chart board can reflect the type of clay minerals simply andintuitively,and can qualitatively determine the type of clay minerals inpractical application. However, the traditional chart can not provide relativerelationship of clay mineral contents and Th/K. Therefore, even the existenceof kaolinite, illite and montmorillonite in the strata can be determined, thetypes of clay minerals are unable to be determined accurately and thecharacteristics of clay minerals can't be calculated accurately. That's nonquantitative.(2),Aiming at the specific issues exit in traditional clay minerals anlysischart,we have improved the clay minerals Th / K chart identification methodon the basis of the previous studies, and get a new clay minerals analysis chart.The new chart is more accurately to identify the type of clay minerals andcalculate clay minerals contents. The improvement of the traditional chart hasbeen achieved in the thesis. After improving, we not only can determine thetype of clay minerals, but also can calculate the clay minerals of arbitrarymeasurement points, and get the clay minerals content distribution in strata directly.(3),Statistic analyze the relationships of clay minerals contents andradioactive elements U, Th, K content on the basis of calculating clay mineralscontent in the new chart. Get the following conclusions: the cross plot issimilar in a single strata section and mixed strata section. This shows that theclay mineral content only relates to the content of radioactive elements, and hasno relations with the strata locates.(4),Establish multivariate linear regression calculation model of claymineral content. The results which from chart calcalation are compared with theresults get by multivariate regression calculation. The comparation has provedthat the method scientific and feasible. It may meet quota requirementsregarding this area clay mineral content computation.This method can be promoted in terms of clay minerals content in thesame area. In addition, according to the multiple linear regression model ofclay mineral content can provide changes of clay mineral content along thelongitudinal axis, which can be as important parameters to be used in otherresearch.(5),Get direction relation of parameters and lithology through statisticalanalysis of main lithology and U, Th, K content and GR value of main strata inJilin oilfield. It provides basis information for further lithology identification.Radioactive elements U, Th, K content and GR value in different strata anddifferent lithology is different. That constitute the basis of lithologyidentification, and it is the prerequisite of lithology identification.(6),Use the dynamic cluster approach to identify lithology in this thesis.Through an example we get: Dynamic cluster method as a simple and efficientclustering method can be used for classification of lithology, and theidentification rate is higher. In addition, the results of cluster analysisreflectes the continuous change of the strata lithology on the vertical. Thosechanges can be as important parameters used in some sides, such as analysis of sedimentary environment, correlation between wells, and so on.In summary, this thesis has utilized the natural gamma-ray Spectrometrylogging data to identify clay minerals type content in Jilin oil field areasuccessfully and quantitatively calculated clay minerals content, and hasachieved certain precision, also carried on lithology recognition with naturalgamma-ray Spectrometry logging data, and has obtained good effect.Application domain of natural gamma-ray Spectrometry logging data isvery broad, more than these which involved above.About the improvement ofclay mineral analysis chart version, this thesis is revision to the boundary valueaiming at Jilin oil field actual situation. Application in other local also shouldrevise the boundary value according to the local actual data statistics. Thisresearch has merely done a part of applied research. As a result of time, energy,there are many application domains not to be involved. If human and materialresources permitted, further extraction and application in view of the gammaraySpectrometry logging data may obtains a bigger result.