低密度水泥固井质量评价方法研究

通过建立模型、合理选择参数模拟出了不同密度水泥固井时第一界面完全胶结和存在缝隙时的理论波形，并对各种胶结情况下的理论波形、幅度的特征进行了对比分析，发现相同胶结状况下低密度水泥固井套管波幅度要比高密度水泥固井套管波幅度明显高，而且两者之间的幅度值具有相关性。为此，利用模拟出的低、高密度水泥固井套管波幅度之间的关系，经曲线拟合、多元回归得到校正公式，将低密度水泥固井套管波幅度校正到高密度水泥固井套管波幅度，再对低密度固井质量采用常规密度水泥固井评价标准进行评价。现场几十口井的应用表明，校正公式法评价低密度水泥固井质量比降低常规固井评价标准的做法效果好。

An Evaluation Method for Cementing Operations with Light Weight Cement

Theoretical wave patterns have been figured out to stimulate the first bonding face of cemented with different slurry density under conditions of complete and partial cementing by establishing models and choosing parameters reasonably. Moreover, the wave pattern and amplitude have been compared among various bonding conditions. The comparison indicates that the wave amplitude of cementing with low weight cement is obviously higher than one with high weight cement, and that the two wave amplitudes are interrelated each other. In view of this situation, we adopt correcting formula to evaluate cement job quality with light weight cement. This method use the relationship of casing wave amplitudes between light weight cement anchoring and high, and we get the correction formula after curve fitting and multiple regressing, then adjust casing wave amplitude under light weight cement to high, so that we can evaluate light weight cement quality with normal weight cement evaluation criterion. After comparative test of dozens of wells in the field finally, this method acquired much better effectiveness than degrading normal weight cement evaluation criterion.