水泥浆性能对声波水泥胶结测井结果的影响

基于声波水泥胶结测井评价解释结果受被测介质声阻抗的影响，采用超声波测试方法探讨了常规水泥浆性能及其对水泥石声阻抗特性的影响规律。实验发现，不稳定的水泥浆体系，因固相颗粒沉降堆积、水泥浆水化不充分及凝固后体积收缩，严重影响了水泥环的层间封隔质量，但因其堆积后水泥石声阻抗值增加，声波水泥胶结测井时首波幅度降低，测井解释结果却较好。此外，空心漂珠低密度水泥石声阻抗值明显低于常规密度水泥石声阻抗值，固井后CBL首波幅度明显高于用常规密度水泥固井后测得的CBL首波幅度，常导致固井评价解释结果偏离实际封隔情况。研究结果表明，在评价固井质量时，应充分考虑水泥浆混合材质特性及水泥浆沉降稳定性对水泥石声阻抗的影响，以真实、合理地反映水泥环层间封隔质量。

INFLUENCE OF CEMENT SLURRY PROPERTIES ON ACOUSTIC CEMENT BOND LOG

Since the evaluation and interpretation of acoustic cement bond log (CBL) is affected by the acoustic impedance of the medium being tested, ultrasonic test method is used to study the properties of conventional cement slurry and their effects on the acoustic impedance of cement stone. The experiment results indicated inside the unstable cement slurry system the solids settle and accumulate, the slurry cannot hydrate sufficiently, and the cement slurry will shrink after being set. These will severely affect the isolation effects of the cement sheath, while making the amplitude of the initial wave of acoustic cement bond logging decreased and thus providing falsely good bond quality interpretation which is due to the fact that the acoustic impedance of the cement stone will be higher after the solids' accumulation. And for the low density hollow bead slurry system, the acoustic impedance of the cement stone is obviously lower than the acoustic impedance of the conventional slurry system, the amplitude of the initial wave of its CBL is obviously higher than that of conventional slurry, making the related cementing evaluation and interpretation results different from the actual situation. The study also demonstrates the effects of the properties of different materials inside the slurry system and the subsidence stability of the slurry on the acoustic impedance of the cement stone should be carefully considered so as to truly reflect the isolation effects of the cement sheath.