声波测井对微环探测能力的研究

微环厚度的评价对于石油工程具有重要意义。本文采用有限元计算方法研究了微环厚度对套管井声波测井初至波幅度的影响。数值计算结果表明，厚度小于1mm的微环对声波初至波测量结果无明显影响，但随着微环厚度的增加，套管与水泥环的声波耦合能力下降，声能量难以进入地层，导致套管波能量增加。本文认为，可以把1mm厚度微环作为微环对固井质量测井产生影响的临界值。

Influence of microannulus' thickness on capacity of acoustic wave-logging tool.

Evaluation of the thickness of microannulus in cased borehole is very important in petroleum engineering.The dependence of amplitude of first break for acoust ic logging in cased borehole on the thickness of microannulus is studied in this paper with Finite Element Method (FEM).The numerical results show when the th ickness of microannulus is less than 1 mm,the variation in the thickness of mi croannulus has a minor effect on the amplitude of acoustic first break;but whe n the thickness of microannulus is larger than 1 mm,the coupling of casing wit h cement becomes weaker,the acoustic energy is difficult to enter the beds,l eading the amplitude of casing wave to increase.The paper considered that the 1 mm thickness of microannulus can be taken as a critical value having influence of microannulus on well-logging aimed at well-cementing quality.