步玉环, 宋文宇, 何英君, 沈兆超. 低密度水泥浆固井质量评价方法探讨[J]. 石油钻探技术, 2015, 43(5): 49-55. DOI: 10.11911/syztjs.201505009
引用本文: 步玉环, 宋文宇, 何英君, 沈兆超. 低密度水泥浆固井质量评价方法探讨[J]. 石油钻探技术, 2015, 43(5): 49-55. DOI: 10.11911/syztjs.201505009
Bu Yuhuan, Song Wenyu, He Yingjun, Shen Zhaochao. Discussion of a Method for Evaluating Cementing Quality with Low-Density Cement Slurries[J]. Petroleum Drilling Techniques, 2015, 43(5): 49-55. DOI: 10.11911/syztjs.201505009
Citation: Bu Yuhuan, Song Wenyu, He Yingjun, Shen Zhaochao. Discussion of a Method for Evaluating Cementing Quality with Low-Density Cement Slurries[J]. Petroleum Drilling Techniques, 2015, 43(5): 49-55. DOI: 10.11911/syztjs.201505009

低密度水泥浆固井质量评价方法探讨

Discussion of a Method for Evaluating Cementing Quality with Low-Density Cement Slurries

  • 摘要: 随着低密度水泥浆固井技术的广泛应用,现有固井质量评价标准已经不能满足要求,因此有必要在充分研究各影响因素的基础上对现有固井质量评价方法进行修正。通过分析井下声场,建立了套管井井下声场模型,结合各因素对水泥石声学特性的影响及固井质量评价标准的制订依据,提出了固井质量评价标准改进方法,并给出了改进条件下固井质量评价标准的操作步骤。通过对比改进条件下与常规条件下的测井响应差异,得到改进后的固井质量测井评价指标。拟合了不同密度下声幅幅值的函数方程,且各方程相关系数均大于0.93。对比拟合方程线性系数发现,微硅低密度水泥浆体系的拟合系数大于漂珠微硅复合低密度水泥浆体系,拟合系数最小的为粉煤灰低密度水泥浆体系;候凝达48 h时,声幅上限各系数分别为20.74,19.15和18.82,声幅下限各系数分别为20.85,14.81和12.96。各低密度水泥浆体系的固井质量评价指标均随密度增大而减小,且具有很强的线性相关性,改进后的评价标准能根据水泥浆种类及其密度值准确地计算出评价指标,该方法对固井质量评价标准的改进具有很强的指导意义。

     

    Abstract: With the application of low density cement slurries, the existing cementing quality evaluation criteria are no longer applicable, so it is necessary to amend the criteria after sufficiently studying the various influencing factors. A downhole acoustic field model for cased wells is established in this paper through analysis of acoustic field. Combining the effect of different factors on acoustic characteristics of set cement with the basis of evaluation criteria for cementing quality, the improvement methods for the criteria was proposed. Furthermore, the operation procedure of improved evaluation criteria for cementing quality was provided.The logging evaluation index for improved cementing quality was obtained by comparing the logging response after improving the conditions with that in conventional conditions.The fitting functional equations of acoustic amplitudes were made by using different densities of cement slurry, the correlation coefficients for all equations are higher than 0.93. Through the comparison of linear coefficients of matching equations, it is shown that the matching coefficient of micro-silica low density cement slurry is higher than that of floating bead micro-silica low density cement slurry, and the lowest one is from the low-density coal ash cement slurry. After waiting on the cement for 48 hours, the upper coefficient limits of their acoustic amplitudes are 20.74, 19.15 and 18.82, and the lower coefficient limits are 20.85, 14.81 and 12.96 respectively. The cementing quality evaluation indices of all low-density cement slurries decrease with increasing density, and they have a very strong linear relationship between them. In light of the improved evaluation criteria, the evaluation indices can be calculated accurately by density of various cement slurries. This method can play an important role for the improvement of cementing quality evaluation criteria.

     

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