Inelastic scattering and capture gama-ray spectra combination analyzing method

Abstract

The invention provides an inelastic scattering and capture gama-ray spectra combination analyzing method which includes the following steps: acquiring inelastic scattering gama-ray spectra and capture gama-ray spectra on a target stratum and selecting reference elements from the target stratum; acquiring the element content of the reference elements according to the capture gama-ray spectra; acquiring relative yield of the reference elements and the relative yield of the elements to be solved according to the inelastic scattering gama-ray spectra; acquiring the element content of the elements to be solved from the in elastic scattering gama-ray spectra according to the element content of the reference elements, the relative yield of the reference elements and the relative yield of the elements to be solved in a combination spectra analyzing method. By means of the method, the element content which is low in capture radiation reaction section and cannot be acquired from the capture gama-ray spectra can be obtained from the inelastic scattering gama-ray spetra.

Description

technical field [0001] The invention relates to the technical field of geophysical well logging, in particular to a combined analysis method of inelastic scattering and captured gamma energy spectrum. Background technique [0002] Formation element logging is to measure the gamma energy spectrum generated by the reaction of neutrons emitted by the neutron source to the formation and the nuclei of formation elements, and use the spectral analysis method to obtain the relative production of formation elements, and then use the oxide closure model to calculate the relative yield of elements. Converting the amount to element content can describe formation parameters more accurately, and provide an effective means for logging evaluation of complex reservoirs and unconventional oil and gas reservoirs. [0003] Si, Ca, Fe, S in the formation can be obtained by using the formation element logging technology of capture gamma energy spectrum (such as the element capture logging tool E...

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Problems solved by technology

However, for key formation elements such as carbon, which is used to evaluate formation organic carbon content, and magnesium, which is used to distinguish limestone from dolomite, the formation element logging technology using capture gamma energy spectroscopy cannot be accurate due to the relatively low capture radiation reaction cross section of these elements. To obtain the content of these elements, it is necessary to analyze the inelastic scattering gamma energy spectrum to obtain the content of key elements such as carbon and magnesium

However, due to the limited relative yield information of elements obtained from inelastic scattering gamma spectrum analysis, and the inelastic scattering gamma energy spectrum does not satisfy the closed model of oxides, the current technology cannot directly analyze the inelastic scattering gamma energy spectrum. Convert the relative yields of elements obtained in

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