摘要
采用液浸探头的超声脉冲反射法难以评价第Ⅱ界面的水泥胶结状况 ,这是因为声波在泥浆 /套管界面存在强烈的反射 ,使绝大多数能量在这个界面上反射的缘故。采用模拟实验研究了超声探头直接耦合于套管内壁的固井质量评价方法。分别使脉冲超声波垂直入射和斜入射于套管内壁 ,在反射波列中可直接观测到明显的第Ⅱ界面信号。考虑到方法的实用 ,在使超声脉冲声波垂直入射于界面时 ,在探头和套管内壁之间夹一薄钢板 ,仍能测得第Ⅱ界面信号。该实验结果表明 ,直接耦合法声系可消除泥浆的影响、明显提高信噪比、能评价第Ⅰ界面的胶结状况 ;在第Ⅰ界面胶结好的情况下可以评价第Ⅱ界面的胶结状况。
Previous research shows that, when the transducer is immersed in slurry, it is nearly impossible to determine the cement bond quality of the interface between the cement annulus and formation (Interface Ⅱ) using the ultrasonic pulse echo technique(UPET). Because strong reflection occurs on the interface between the slurry and casing, most portion of the pulse energy is reflected back. In this paper, methods of cement bond evaluation are studied in four different model experiments, in which the transducer is contacted closely to the casing. In these experiments, no matter whether the ultrasonic pulses are normally or obliquely incident upon the casing, obvious signals corresponding to the Interface II are observed. Considering the practical implementation of the technique, a thin steel plate is inserted between the transducer and casing. The reflection signal can still be achieved. The model experiments indicate that the transducer-contact-casing system can eliminate the influence of the slurry, improve the ratio of signal to noise, evaluate the interface between the casing and cement (Interface I), and determine the cement bond quality of the Interface II if the Interface I is well bonded.
出处
《测井技术》
CAS
CSCD
2004年第5期392-396,共5页
Well Logging Technology
关键词
超声脉冲反射技术
声系
耦合
斜入射
固井质量
ultrasonic pulse echo technique
acoustic configuration
contacting
oblique incidence
ce- ment bond quality
