Study On Influence Factors And Correction Method Of Elemental Yield In Geochemical Well Logging With Controllable Source

In geochemical well logging,in order to obtain accurate dry weights of elements in formation,it is necessary to obtain high precision elemental yields when analysing spectrum.Complex formation mineral composition and borehole environment will affect the acquisition of elemental yield.Large error in elemental yield will lead to inaccurate calculation of element weight fractions,which will directly affect the subsequent determination of inorganic and organic mineral composition type and content of reservoir.In this paper,using MCNP Monte Carlo simulation program,the difference of standard spectrum obtained by different tally types is discussed,and the influence factors such as borehole diameter,porosity,salinity,borehole medium,compaction degree and formation filling material on standard spectrum of different tally types is analyzed.On the basis of the yield obtained by analysing the measured spectrum of formation under the influence of different factors,the influence of each factor on yield acquisition is analyzed.According to the influence degree of each factor,the correction method of borehole diameter and porosity is selected,and the corresponding correction formula is obtained.The correction method is verified by data processing of model wells and actual wells.The results show that the influence of borehole diameter,porosity and salinity on elemental yield is obvious;the influence of borehole medium can be classified into the influence of borehole diameter and salinity;the influence of compaction degree and formation filling material on elemental yield is small;the correction effect of correction method is better.