Neutron transport correction and density calculation in the neutron-gamma density logging

Wang, Hu; Wu, Wensheng; Wang, Ruigang; Ge, Yunlong

doi:10.1016/j.apradiso.2019.05.023

Cited by 12 publications

(3 citation statements)

References 3 publications

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“…Density , is a unique property of matter, and the densities of the four fluids are different from each other. It can be seen from Figure that irrespective of whether it is a sandstone formation or a carbonate formation, the formation density changes with the porosity and the four fluids are clearly distinguished under different porosities.…”

Section: Methodsmentioning

confidence: 99%

Machine Learning-Based Qualitative Identification of Four-Phase Fluid in Reservoir

Wang,

2023

ACS Omega

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The identification of fluid types has always been the focus of oil and gas field exploration and development research. At this stage, a large amount of CO 2 has been found in many basins during exploration and development, which greatly affects the accuracy of reservoir understanding and evaluation, so it is very important to accurately identify the fluid type of the CO 2 -bearing reservoirs. However, methods utilizing multiple logging data are greatly affected by physical changes in the formation, resulting in methods that are only applicable to the area and layer under study, are poorly generalized, and require multiple instruments and experimental support. Existing nuclear logging methods that primarily utilize logging curve stacking and intersection map methods fail to take full advantage of logging. In this study, taking advantage of the fact that the neutron gamma technique of nuclear logging measurement can provide multiparameter information with the characteristics of machine learning to deal with multidimensional data, comparing the classification results of different ware learning methods under different classification strategies and selecting a method of identifying fluids in logging while drilling was based on the idea of dichotomy and the use of the support vector machine as a meta-model. This solved the problem of identifying fluids in the CO 2 -bearing reservoirs, providing new ideas for the design and fabrication of logging instruments. These instruments can assist with the exploration and development of oil and gas fields and has a broad application prospect in CO 2 -EOR and CCUS.

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Section: Methodsmentioning

confidence: 99%

Machine Learning-Based Qualitative Identification of Four-Phase Fluid in Reservoir

Wang,

2023

ACS Omega

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“…Based on Lagrange's mean value theorem, bulk density can be expressed as follows (Wang et al, 2019):…”

Section: Correction Of the Effects Of Neutron Transport And Pair Prod...mentioning

confidence: 99%

“…Their theoretical tool consists of two gamma ray detectors and several fast neutron detectors. Using the coupled field theory and based on the principle of energy window compensation, Wang et al (2019); Wang et al (2020) obtained the density estimation algorithm insensitive to formation lithology and pore fluid.…”

Section: Introductionmentioning

confidence: 99%

Bulk Density Response and Experimental Study of Pulsed Neutron-Gamma Density Logging

Wang¹,

Yue²,

Zhang³

et al. 2022

Front. Earth Sci.

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The pulsed neutron-gamma density logging technique is used to measure the bulk density of formations based on the detection of gamma rays from the inelastic scattering of neutrons in the formations. However, the induced gamma ray source is regarded as a function of neutron transport and cannot be considered a “point” source. Due to the high energy level of gamma rays, the attenuation of inelastic gamma rays is affected by Compton scattering and pair production. Therefore, bulk density can be measured using inelastic gamma rays while considering the effects of neutron transport and pair production. In this article, a novel density measurement method that uses a completely different response model is proposed to improve the accuracy of density measurement. The process of neutron-gamma density measurement is divided into the neutron transport group and the gamma ray transport group in accordance with the neutron-gamma coupled field theory. A novel density estimation algorithm is derived from the diffusion equation and the gamma ray attenuation law. The accuracy and specification of density measurement are investigated through the Monte Carlo simulation and the calibration of test pits. Theoretical and experimental analyses show that the neutron transport and gamma ray transport are not entirely independent of each other in the pulsed neutron-gamma density measurement. The newly developed model can effectively enable the inelastic gamma rays to conform to the gamma ray attenuation law and keep the measurement accuracy at ±0.025 g/cm3. Moreover, neutron-gamma density is insensitive to the porosity and lithology of the formation. The proposed novel algorithm successfully establishes the calculation model for the relationship between inelastic gamma rays and bulk density, providing a new perspective for density measurement in pulsed neutron-gamma density logging.

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Novelty in the interpretation of gamma rates recorded by a pulse neutron-gamma probe for gas reservoir determination

Zhang

Song

et al. 2023

J Radioanal Nucl Chem

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Neutron transport correction and density calculation in the neutron-gamma density logging

Cited by 12 publications

References 3 publications

Machine Learning-Based Qualitative Identification of Four-Phase Fluid in Reservoir

Machine Learning-Based Qualitative Identification of Four-Phase Fluid in Reservoir

Bulk Density Response and Experimental Study of Pulsed Neutron-Gamma Density Logging

Novelty in the interpretation of gamma rates recorded by a pulse neutron-gamma probe for gas reservoir determination

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