The interior tomography is commonly met in practice, whereas the self-calibration method for geometric parameters remains far from explored. To determine the geometry of interior tomography, a modified interval subdiv...The interior tomography is commonly met in practice, whereas the self-calibration method for geometric parameters remains far from explored. To determine the geometry of interior tomography, a modified interval subdividing based method, which was originally developed by Tan et al.,^[11] was presented in this paper. For the self-calibration method, it is necessary to obtain the reconstructed image with only geometric artifacts. Therefore, truncation artifacts reduction is a key problem for the self-calibration method of an interior tomography. In the method, an interior reconstruction algorithm instead of the Feldkamp-Davis-Kress （FDK） algorithm was employed for truncation artifact reduction. Moreover, the concept of a minimum interval was defined as the stop criterion of subdividing to ensure the geometric parameters are determined nicely. The results of numerical simulation demonstrated that our method could provide a solution to the self- calibration for interior tomography while the original interval subdividing based method could not. Furthermore, real data experiment results showed that our method could significantly suppress geometric artifacts and obtain high quality images for interior tomography with less imaging cost and faster speed compared with the traditional geometric calibration method with a dedicated calibration phantom.展开更多
The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even le...The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).展开更多
基金supported by the National Basic Research Program of China(Grant No.2011CB707701)the National High Technology Research and Development Program of China(Grant No.2012AA011603)the National Natural Science Foundation of China(Grant Nos.30970772 and 61372172)
文摘The interior tomography is commonly met in practice, whereas the self-calibration method for geometric parameters remains far from explored. To determine the geometry of interior tomography, a modified interval subdividing based method, which was originally developed by Tan et al.,^[11] was presented in this paper. For the self-calibration method, it is necessary to obtain the reconstructed image with only geometric artifacts. Therefore, truncation artifacts reduction is a key problem for the self-calibration method of an interior tomography. In the method, an interior reconstruction algorithm instead of the Feldkamp-Davis-Kress （FDK） algorithm was employed for truncation artifact reduction. Moreover, the concept of a minimum interval was defined as the stop criterion of subdividing to ensure the geometric parameters are determined nicely. The results of numerical simulation demonstrated that our method could provide a solution to the self- calibration for interior tomography while the original interval subdividing based method could not. Furthermore, real data experiment results showed that our method could significantly suppress geometric artifacts and obtain high quality images for interior tomography with less imaging cost and faster speed compared with the traditional geometric calibration method with a dedicated calibration phantom.
文摘The mechanical behavior of the test string in deep wells is generally relatively complex as a result of the high temperature and high pressure,severe dogleg and buckling effects,which in some circumstances can even lead to string failure.Traditional computational methods for the analysis of these behaviors are often inaccurate.For this reason,here a more accurate mechanical model of the test string is introduced by considering variables such as temperature,pressure,wellbore trajectory,and buckling,as well as combining them with the deformation and string constraint conditions brought in by changes in temperature and pressure during the tripping,setting,and test operations.The model is validated by applying it to a specific high-pressure gas well(located in Northeast Sichuan).
