Study On The Method For Calculating And Optimizing The Resolution Of Gamma Imaging While Drilling

The azimuthal gamma imaging logging while drilling is one of the items that must be measured in LWD.It can provide immediate lithology information and guide the direction in which the drill bit is drilled to guide the drilling well to the optimal target formation.At present,more researches are being done on the optimization design of the azimuthal gamma imaging logging tools while drilling and the vertical resolution and the radial depth of investigation.There is little research on the azimuthal detection characteristics of the tools,but for the anisotropic formation,it is important to study the azimuthal resolution optimization of the tools.In this paper,a numerical calculation model is established.From the results of Monte Carlo numerical calculation,a method for calculating the azimuthal resolution of the azimuthal gamma imaging logging tools while drilling is proposed.On the basis of considering the influences of mud properties,formation density,borehole radius,mud density and porosity on the azimuthal differential geometric factor,the general azimuthal resolution response function is obtained;Combining the response characteristics of the tools with different azimuthal angles,the corresponding formation characteristics are inverted.And the corresponding representative values of the radioactive intensity in different sectors are obtained to achieve the purpose of resolving the multi-sector formation.The research shows that this optimization method can make the azimuthal resolution reach 22.5° and distinguish the formation of 16 sectors,the absolute values of its calculation errors do not exceed 5%.The formation response characteristics obtained by this optimization method will guide the geosteering more accurately and find more favorable oil and gas blocks.