Water layer neutron logging in multi-angle crack environment
Xue-Ang ZHANG1,2, Zhi-Chao YANG3, Xiong WEI1
1. Engineering Research Center of Nuclear Technology Application, Ministry of Education,East China University of Technology,Nanchang 330013,China 2. School of Nuclear Science and Engineering,East China University of Technology,Nanchang 330013,China 3. School of Geophysics and Measurement-control Technology,East China University of Technology,Nanchang 330013,China
In geophysical exploration,crack medium is an important potential reservoir medium,and because of its complex structure and characteristics,the detection difficulty of crack medium is always great.For the purpose of identifying and studying the crack medium,it is necessary to conduct exploration and research through geophysical neutron logging method.In this paper,the authors applied the theory of dispersed multi-angle cracks to simulating the water layer strata in the pore-crack medium.The corresponding neutron log data were studied by changing crack parameters.The results of the study show that,in the low and medium angle crack environment,the maximum thermal neutron density is larger than that of approximate horizontal angle crack medium,and its sensitivity is significantly greater than that of other kinds crack environment,and that,in the high angle crack medium,the thermal neutron density map is smooth,indicating that the high angle crack medium has little effect on thermal neutron absorption.In the thermal neutron density distribution plan,the thermal neutron diffusion range is small because of the high hydrogen content in water.By analyzing the water layer thermal neutron density distribution,the maximum density distribution and the maximum time spectrum,the authors found that the neutron in the water layer is more sensitive to low and medium angle crack media,and is easy to be slowed down and absorbed.These results can provide theoretical guidance for geophysical survey work in the field.
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