Prediction of mechanical parameters for low-permeability gas reservoirs in the Tazhong Block and its applications

 A longitudinal distribution profile of the mechanical properties of the formations is important for the safe drilling, successful completion, and development of oil and gas reservoirs. However, the mechanical profile of the carbonate formations from the low-permeability gas reservoirs in the Tazhong (TZ) Block is hard to achieve due to the complex structural and lithological characteristics of the carbonates. In this paper, lab measurements are carried out to determine the physical and mechanical properties of the carbonate rocks of the Yingshan Formation in the TZ Block. Based on this, the relationships among density, the interval transit time and the mechanical parameters of the rocks in the TZ Block are constructed. The constructed relationships are then applied to the well-logging prediction of the mechanical profiles of the carbonate formations. The models are verified through the application to the two wells in the TZ Block, the results show that the relative errors in the predicted mechanical parameters are within 10% indicating the efficiency of the constructed models. The result of this study provides reasonable mechanical parameters for the exploration and development of the carbonate reservoirs in the TZ Block.Cited as: Wan, Y., Zhang, H., Liu, X., Yin, G., Xiong, J., Liang, L. Prediction of mechanical parameters for low-permeability gas reservoirs in the Tazhong Block and its applications. Advances in Geo-Energy Research, 2020, 4(2): 219-228, doi: 10.26804/ager.2020.02.1

A Multilayer-Stacked UWB Yagi Antenna

By taking advantage of a wideband bow-tie antenna in the Yagi configuration, a novel multilayer-stacked ultra-wideband (UWB) Yagi antenna is proposed. First, the fundamental 3-layered UWB Yagi model is studied with respect to a few critical dimensions. Then, several directors are added to form a multilayer-stacked Yagi antenna, where the width of the directors is optimized in a monotonic decreasing manner. A sixlayered UWB Yagi antenna is studied by simulations. It covers 3.4-10.6 GHz with its return loss better than 10 dB, and it achieves a high directivity up to 13 dBi and a relative cross-polar level better than -10 dB in the whole band

SLX4 Assembles a Telomere Maintenance Toolkit by Bridging Multiple Endonucleases with Telomeres

SummarySLX4 interacts with several endonucleases to resolve structural barriers in DNA metabolism. SLX4 also interacts with telomeric protein TRF2 in human cells. The molecular mechanism of these interactions at telomeres remains unknown. Here, we report the crystal structure of the TRF2-binding motif of SLX4 (SLX4TBM) in complex with the TRFH domain of TRF2 (TRF2TRFH) and map the interactions of SLX4 with endonucleases SLX1, XPF, and MUS81. TRF2 recognizes a unique HxLxP motif on SLX4 via the peptide-binding site in its TRFH domain. Telomeric localization of SLX4 and associated nucleases depend on the SLX4-endonuclease and SLX4-TRF2 interactions and the protein levels of SLX4 and TRF2. SLX4 assembles an endonuclease toolkit that negatively regulates telomere length via SLX1-catalyzed nucleolytic resolution of telomere DNA structures. We propose that the SLX4-TRF2 complex serves as a double-layer scaffold bridging multiple endonucleases with telomeres for recombination-based telomere maintenance