| Internationally, Schlumberger, Halliburton, Baker-Atlas, Russian logging companies and other companies have developed a chemical element formation logging equipment. The instrument can solve the problem of complex lithology identification from the angle of rock composition, and it is also a new technology for the comprehensive evaluation of the reservoir, which can identify shale gas and coal bed methane well. The chemical element logging has become an important method in the new generation of logging technology. So it is the need that setting up the research on the development of chemical element logging tools, learning the advanced design experience, get rid of the backwardness, and tracking the world’s advanced technologies.After the previous research work, the chemical elements logging technology has been mastered, and the comparative analysis on the existing elements logging instrument has been carried out, which against the foreign logging company. Foreign logging companies’ instruments are different in the method of the source, the size of the instrument, the speed, the obtaining of standard spectrum, these are all the problems which need to be solving in the process of development. The obtaining of standard spectrum and the method of settlement are emphatically studied in this paper.This paper introduces the theoretical basis of elements logging, the principle of the instrument and the process of explain. And the formation and instrument model are built by using Monte Carlo simulation technique. The multi group of cross section and reconciliation with transport equation are used in the process of simulation, and the neutron, photon, electron transport and combined transport are used to make the simulation be closed to the actual application result as far as possible. The theoretical model has been verified by the c/o ratio instrument of Daqing logging company, and the response characteristics of the c/o ratio instrument are simulated successfully under the condition of pure water, which is proved that the establishment of model and the method of obtaining standard spectrum are reasonable. So the parameters could be further improved, and through deepening the research, the standard spectrum of formation could be obtained in other lithology and formation fluid state.After getting the element standard spectrum, the method for solution of spectrum is studied emphatically. In order to eliminate the measurement error which is caused by the difference of instrument on hardware, the method of instrument calibration is researched. In order to solve the problem of instrument drift in the process of measuring, the Marquardt nonlinear iteration is studied, which is the study of the stabilizer. In order to get the dry weight of the element, the spectrum stripping is studied. The elements of dry formation are existed in the form of oxide, so the sum of the percentage of various oxides should be 1, and in order to get the percentage content of elements in strata, the method of oxide closure is researched. In order to make the percentage of various elements correspond to the corresponding lithology, the method of lithology analysis is studied. Through the above methods, the problem of spectrum analysis in the spectral lines of actual measurement can be solved.After the successful development of a prototype instrument, the instrument is simulated for indoor and physical indicators test, and the validated results are up to the requirements of the development.The instrument prototype is tested in the field. There are 6 test wells in the scale wells floor of Daqing Drilling Engineering Company. There are 25 wells being tested, which include 14 wells of adjustment, 4 wells of peripheral development, and 7 wells of wildcat. The repeatability and consistency of the instrument are explained by the experts, which has good repeatability, and the instrument has good consistency with ECS. The research further validates the correctness of method of standard spectrum acquisition and the solution of spectrum. |
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