Experiments on acoustic measurement of fractured rocks and application of acoustic logging data to evaluation of fractures
投稿时间:2016-09-06  
英文关键词:Fractured rock, Acoustic wave velocity, Acoustic wave amplitude, Experimental measurement, Fracture width
基金项目:This work was supported in part by the National Natural Science Foundation of China (Grant No. 41174096) and was supported by the Graduate Innovation Fund of Jilin University (Project No. 2016103).
作者单位
Bao-Zhi Pan Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
Ming-Xin Yuan Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
Chun-Hui Fang Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
Wen-Bin Liu Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
Yu-Hang Guo Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
Li-Hua Zhang Faculty of Geo-exploration Science and Technology, Jilin University, Changchun 130012, Jilin, China 
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英文摘要:
      Fractures in oil and gas reservoirs have been the topic of many studies and have attracted reservoir research all over the world. Because of the complexities of the fractures, it is difficult to use fractured reservoir core samples to investigate true underground conditions. Due to the diversity of the fracture parameters, the simulation and evaluation of fractured rock in the laboratory setting is also difficult. Previous researchers have typically used a single material, such as resin, to simulate fractures. There has been a great deal of simplifying of the materials and conditions, which has led to disappointing results in application. In the present study, sandstone core samples were selected and sectioned to simulate fractures, and the changes of the compressional and shear waves were measured with the gradual increasing of the fracture width. The effects of the simulated fracture width on the acoustic wave velocity and amplitude were analyzed. Two variables were defined: H represents the amplitude attenuation ratio of the compressional and shear wave, and x represents the transit time difference value of the shear wave and compressional wave divided by the transit time of the compressional wave. The effect of fracture width on these two physical quantities was then analyzed. Finally, the methods of quantitative evaluation for fracture width with H and x were obtained. The experimental results showed that the rock fractures linearly reduced the velocity of the shear and compressional waves. The effect of twin fractures on the compressional velocity was almost equal to that of a single fracture which had the same fracture width as the sum of the twin fractures. At the same time, the existence of fractures led to acoustic wave amplitude attenuations, and the compressional wave attenuation was two times greater than that of the shear wave. In this paper, a method was proposed to calculate the fracture width with x and H, then this was applied to the array acoustic imaging logging data. The application examples showed that the calculated fracture width could be compared with fractures on the electric imaging logs. These rules were applied in the well logs to effectively evaluate the fractures, under the case of no image logs, which had significance to prospecting and development of oil and gas in fractured reservoirs.
Bao-Zhi Pan,Ming-Xin Yuan,Chun-Hui Fang,Wen-Bin Liu,Yu-Hang Guo,Li-Hua Zhang,2017.Experiments on acoustic measurement of fractured rocks and application of acoustic logging data to evaluation of fractures.Petroleum Science,(3):520~528.
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