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Modeling of micro-annulus propagation along cementing interface in stimulated horizontal wellbore
Yan Yan,Guan Zhichuan,Yan Weijun 한국자원공학회 2021 Geosystem engineering Vol.24 No.5
Once there are micro-annulus at cementing interfaces in the process of reservoir stimulation, it is easy to form fluid channeling in the later development. Fluid channeling reduces the efficiency of reservoir development and even the service life of oil and gas wells. Based on the characteristics of ‘multi-stage’ in stimulated reservoir volume, a mathematical model was set up to calculate the interface debonding length driven by hydraulic pressure. The propagation process of microannulus in stimulated reservoir volume was also analyzed. The results show that the propagation speed of the micro-annulus gradually slows down with the progress of fracturing. Meanwhile, the debonding azimuth of the micro-annulus and the cement elastic modulus have dominant effects on the propagation length. It is recommended that the setting position of the packer be outranged from the debonding area of the cementing interface in the design of the stimulated reservoir volume scheme to avoid fluid channeling between the stages. This study can predict the unsealing length of cement sheath during hydraulic fracturing as a reference for the optimization of fracturing parameters.
Embryoid bodies formation from chicken primordial germ cells
Hui Xiong,Yabin Pu,Qingyun Hu,Zhiqiang Shan,Pengfei Hu,Weijun Guan,Yuehui Ma 한국통합생물학회 2015 Animal cells and systems Vol.19 No.3
Primordial germ cells (PGCs) were demonstrated to be multipotential because of their differentiation ability in all embryonic lineages and because the pluripotential nature of PGCs caters for recent researches on stem cells. PGCs were cultured in suspension to form embryoid bodies (EBs). The characterization of PGCs and EBs was assessed by immunofluorescence technique, reverse transcription-polymerase chain reaction (RT-PCR) and paraffin section for Haematoxylin and Eosin (HE) stain. We established a stable chicken PGC line in vitro and prepared masses of EBs from PGCs. We also demonstrated that PGCs expressed stage-specific and stem cell-specific surface makers: SSEA-1, SSEA-3, Oct4, and Sox2. EBs expressed specific genes from three germ layers: gene AFP from entoderm, gene GATA6 from mesoderm, and gene Sox3 from ectoderm. The HE staining illustrated that EBs developed different cell types; relatively larger EBs (440 μm in diameter) were obtained, which contract rhythmically. We concluded that chicken PGCs were suitable for the formation of EBs. Abundant larger size EBs could be prepared in an effective way with our protocol, which could construct a good animal model and provide a useful clinical platform in studying human embryonic development and cell transplantation field.