Radio variability of the blazar S5 0716+714: a ∼6.1 year quasi-periodicity     

Xiao-Pan Li  Yu-Hui Luo  Hai-Yan Yang  Cheng Yang  Yan Cai  Hai-Tao Yang  Li Zhou  Yu-Qiong Shan 《Astrophysics and Space Science》2018,363(8):169

We report a ～6.1 yr quasi-periodicity for the blazar S5 0716+714 using the radio light curves at 4.8, 8 and 14.5 GHz observed by the University of Michigan Radio Astronomical Observatory (UMRAO) from 1981 to 2012, by means of the Jurkevich, discrete correlation function (DCF) and power spectral analysis techniques. There are a general correlation among light curves at different frequencies and a time lag of \(170\pm 10\) days between 4.8 and 14.5 GHz light curves can be confirmed. We also estimate the orbit parameters assuming a binary black hole system, and the magnetic field strength under the jet comoving frame.  相似文献   

连通域标识法在FMI图像溶洞信息定量拾取中的应用          下载免费PDF全文

闫建平  梁强  李尊芝  耿斌  寇小攀  扈勇 《地球物理学报》2016,59(12):4759-4770

溶蚀孔洞在碳酸盐岩储层中是重要的流体储集空间,研究成像测井(FMI)图像孔洞连通域标记及信息定量拾取很有意义.全井眼微电阻率成像测井(FMI)经数据处理后可得到全井壁高分辨率的彩色图像,经图像灰度化、中值滤波处理后,通过阈值分割得到能够反映井壁溶蚀孔洞特征的二值图像,孔洞表现为黑色暗斑.基于等价对处理的图像连通域标记算法具有快速、不重复标记的优点,利用该算法,可准确地从二值图像中标记溶蚀孔洞连通域,进而可对每个连通域进行目标信息拾取,包括孔洞尺寸、连通域面积、圆度等.利用反映溶蚀孔洞发育程度的面孔率曲线对图像进行分层,在此基础上可拾取每一层段溶蚀孔洞面孔率、分选系数及溶洞密度值的分布等非均质信息,能够定量地评价溶蚀孔洞发育、非均质性强的碳酸盐岩储层,也是FMI图像应用于岩石孔洞结构信息定量表征新的尝试.  相似文献   

湖南早志留世沉积演化及页岩气勘探前景     

肖盼  郭建华  李杰  王张虎  王玺凯 《沉积与特提斯地质》2017,37(1):79-87

受加里东运动影响,湖南下志留统地层主要分布在湘西北和湘中-湘南地区。随着构造运动、盆地演变和海平面下降,湖南早志留世岩相古地理也发生了巨大的变化。综合露头剖面、钻井岩心和岩石薄片的观察,结合数据分析和前人研究成果,在下志留统识别出比较典型的沉积相:湘西北主要发育陆棚、潮坪、三角洲等浅海相,湘中-湘南主要为深水浊积岩相。文中恢复了下志留统沉积演化,分析了龙马溪组黑色页岩发育特征及其受控因素,建立了页岩沉积模式。  相似文献   

Nuclear magnetic resonance <Emphasis Type="Italic">T</Emphasis><Subscript>2</Subscript> spectrum: multifractal characteristics and pore structure evaluation     

Jian-Ping Yan  Xu He  Bin Geng  Qin-Hong Hu  Chun-Zhen Feng  Xiao-Pan Kou  Xing-Wen Li 《应用地球物理》2017,14(2):205-215

Pore structure characteristics are important to oil and gas exploration in complex low-permeability reservoirs. Using multifractal theory and nuclear magnetic resonance (NMR), we studied the pore structure of low-permeability sandstone rocks from the 4th Member (E_S4) of the Shahejie Formation in the south slope of the Dongying Sag. We used the existing pore structure data from petrophysics, core slices, and mercury injection tests to classify the pore structure into three categories and five subcategories. Then, the T₂ spectra of samples with different pore structures were interpolated, and the one- and three-dimensional fractal dimensions and the multifractal spectrum were obtained. Parameters α (intensity of singularity) and f (α) (density of distribution) were extracted from the multifractal spectra. The differences in the three fractal dimensions suggest that the pore structure types correlate with α and f (α). The results calculated based on the multifractal spectrum is consistent with that of the core slices and mercury injection. Finally, the proposed method was applied to an actual logging profile to evaluate the pore structure of low-permeability sandstone reservoirs.  相似文献