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| Tracer characteristics based on thermal neutron detection method for fractures |
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CHEN Qian1, ZHANG Feng1,2, ZHANG Quanying1, WANG Xinguang1,2, QIU Fei1, WANG Yang1, LI Xianghui3, TAN Haizhou4
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(1.School of Geosciences in China University of Petroleum(East China), Qingdao 266580, China;2.Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China;3.Isotope Research Institute of Henan Academy of Sciences Company Limited, Zhengzhou 450000, China;4.Shengli Oilfield Dynamic Monitoring Center, SINOPEC, Dongying 257000, China)
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| Abstract: |
| Aiming at thermal-neutron tracer detection method of fractures, the dual-group diffusion theory and Monte Carlo numerical simulation method are combined to analyze the thermal neutron characteristic distribution of the formation before and after fracturing. In addition, the fracture responses of thermal neutron count-rate to different types and content of tagged proppants were simulated. The best tracer was selected and its upper and lower limits were calculated in tagged proppants. The results show that the change in thermal neutron count before and after fracturing is mainly dominated by fracture width and the tracer content of tagged proppant. The gadolinium is the best tracer for tagged proppant, which is sensitive to the variety of fracture width. Moreover, with the increase of gadolinium oxide content in tagged proppant, the thermal neutron count-rate declines and the change of thermal neutron count rate (D) increases accordingly. The upper and lower limits of gadolinium oxide in the tracer decrease exponentially with the fracture width. When the fracture width is 1.0 cm, the upper and lower limit of Gd2O3 is 0.68% and 0.03%, respectively. |
| Key words: fracture evaluation thermal neutron detection tracer content nuclear well logging Monte Carlo Simulation |
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