Determining The Relationship Between Horizontal Well Trajectory And Formation And Density Log Correction

Although the horizontal well technology has been widely used in fields,because of logging features different with vertical well,the difficulty of the formation evaluation is increased.Besides the contact relationship between the formation and horizontal wells,compared to vertical wells is the more complex,which has a great influence on the density log response.Even for the same formation,there is a large difference of density log curves between the pilot hole well and horizontal well,and the density log is required to be corrected in the horizontal well logging interpretation.In this paper,the relationship between the formation and well-bore trajectory is understood by constructing the earth model.Density logging is simulated on the basis of the formation model combined with spatial sensitivity function.The impact of the surrounding rock,inclination and cutting bed is eliminated by numerical simulation and the corresponding theoretical correction plate is formed.The two dimension density image is simulated by dynamic relationship between spatial sensitivity function and layer interfaces.Studying the impact of cutting bed is based on the spatial sensitivity theory,making the corresponding correction chart,and the influence of the spiral borehole is corrected by borehole denoising.Finally density logging correction is completed.In addition,through the data reconstruction,spectrum analysis and the construction of the corresponding filter,the horizontal wells in the actual logging data in the common periodic noise phenomenon is eliminated.Through this study,conclusions are listed as follows:1.The relationship between the horizontal well trajectory and the formation is the basis of the horizontal well logging interpretation and related research.Comprehensive variety of information,which contains logging data from pilot hole well and adjacent well,seismic data and geologic information,is needed to make the earth model close to reality as possible.2.In this paper,the concept of spatial response distribution function of density logging is proposed.It is considered that the product of the flux distribution of the gamma ray in the formation space and the contribution of the different volume of space to the gamma ray recorded by the detector.The Monte Carlo method is used to establish the spatial response distribution function under different formation conditions.Simulated in the horizontal well.The simulation results are in good agreement with the Monte Carlo simulation results.But the calculation speed is tens of thousands of times than directly using the Monte Carlo simulation and the method meets the needs of the horizontal well rapid modeling,and achieve density logging imaging simulation.The picking dip coincide with the model dip.3.It is found that the variation rule of the geometric factor of the light cutting bed is different from weight cutting bed factors,but the variation rule of the geometric factor of the different density light cutting bed is approximately the same in a certain thickness.4.The periodic noise in the horizontal well logging data can be approximated as a sine wave of different frequencies.By analyzing the reconstructed data,the corresponding filter can be constructed to eliminate the influence of periodic noise in the horizontal well logging data.