Research on identification model of element logging shale formation based on IPSO-SVM

In the process of shale gas drilling,geo-steering plays an important role in shale gas drilling.This paper analyzes the constituent elements of shale formation,and selects the most suitable constituent elements of shale formation.A particle swarm optimization algorithm based on improved inertia weight and acceleration factor is proposed to optimize the parameters of support vector machine.The lithology identification model of shale formation is established based on IPSO-SVM.According to the experimental analysis based on the field historical data,the recognition rate of IPSO-SVM is increased by 17.79%,10.17%and 8.05%,respectively,compared with SVM,GA-PSO and PSO-SVM.In terms of running time,the running time of IPSO-SVM is 13.76s and 9.5s shorter than that of GA-PSO,PSO-SVM,respectively.By comparing the experimental results of different models,IPSO-SVM has the advantages of strong robustness,strong reliability,high accuracy and fast convergence speed.It provides a theoretical basis for precise geo-steering and finding the optimal shale layer.

Standard spectrum measurement and simulation of elemental capture spectroscopy log

We have established a set of laboratory measurements which is used for capturing element gammma spectrum. Standard captured gamma ray spectra for ten elements, including Si, Ca, Fe, are obtained using the measurements for the first time in China. We also simulated the capture gamma ray spectra of the ten elements using Monte Carlo methodology with the same parameters of our experimental measurements. Comparing the experiment and simulation results with the data from the International Atomic Energy Agency＇s Nuclear Data Center, we obtained the standard captured gamma ray spectra of the ten elements, which, as calibration spectra, are used to calibrate the raw spectrum in data processing. This method solved the key problem during the conversion from the original measuring spectrum to the yield of each element in the data processing. The method can effectively improve the accuracy of the element yield calculation.

Analysis of the elemental spectral characteristics of single elemental capture spectrum log using Monte-Carlo simulation

In this study,the gamma-ray spectrum of single elemental capture spectrum log was simulated.By numerical simulation we obtain a single-element neutron capture gamma spectrum.The neutron and photon transportable processes were simulated using the Monte Carlo N-Particle Transport Code System(MCNP),where an Am–Be neutron source generated the neutrons and thermal neutron capture reactions with the stratigraphic elements.The characteristic gamma rays and the standard gamma spectra were recorded,from analyzing of the characteristic spectra analysis we obtain the ten elements in the stratum,such as Si,Ca,Fe,S,Ti,Al,K,Na,Cl,and Ba.Comparing with single elemental capture gamma spectrum of Schlumberger,the simulated characteristic peak and the spectral change results are in good agreement with Schlumberger.The characteristic peak positions observed also consistent with the data obtained from the National Nuclear Data Center of the International Atomic Energy Agency.The neutron gamma spectrum results calculated using this simple method have practical applications.They also serve as an reference for data processing using other types of element logging tools.