CBMT第二界面成像理论和实验研究

长期以来,固井质量测井主要利用声波法探测水泥环第一界面进而评价固井质量,水泥环第二界面是水泥封隔系统的最薄弱环节,其胶结状况评价则一直是固井质量评价的重大难点,通常只能根据声波变密度测井曲线进行定性评价,第二界面胶结评价是测井追求的目标。该文在中海油服自主研发的扇区水泥胶结成像测井仪器CBMT基础上,利用CBMT仪器测量的贴壁全波波形,采取系统的数值模拟配以适当的实验室物理模拟相结合的方式,研究了利用水泥环外侧反射波进行第二界面胶结状况评价的技术可行性及影响因素,得出了在CBMT仪器贴壁全波波形中,来自于水泥环外侧的反射波幅度与第二界面胶结差扇区大小关系明显,利用其对水泥环第二界面胶结状况进行评价是可行的结论,并对第二界面胶结差扇区分辨率、适应的水泥环厚度及地层条件进行了探讨。

CBMT second Interface imaging theory and experimental study

For a long time, logging is mainly used to detect the first interface of cement by Sonic logging method and then evaluate cementing quality. Cementing condition evaluation of cement second interface has been a major difficulty in cementing quality evaluation, and it is usually only qualitative evaluation according to the VDL of sonic variable density 1]. Based on the CBMT of the cement cementation imaging logging instrument developed by COSL, this paper presents and proves the feasibility and influence factors of the second interface imaging technology by using the second interface reflection wave of the cement by using the CBMT-wall full-wave shape and combining the system numerical simulation with the appropriate laboratory physical simulation. Finally, the second interface imaging of the cement is realized by the experimental well measurement method, which is consistent with the experimental well design model.