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鉴于微泡钻井液在衰竭油气藏钻井中的成功应用,通过实验测试和数据分析研究了微泡钻井液的流变性及稳定性。配制了一种典型的微泡钻井液,在不同温度下对其黏度进行测试,分别采用幂律模型、宾汉塑性模型和Herschel-Bulkley模型对测试数据进行了拟合,发现Herschel-Bulkley模型更能准确描述不同温度下微泡形成前后钻井液的流变性。根据Herschel-Bulkley模型拟合结果,温度升高会提高微泡钻井液的剪切稀释程度,微泡形成后钻井液的静切力和井眼净化能力提高,且在高温下微泡钻井液性能不会明显减弱。低剪切速率下微泡钻井液具有较高的黏度,可以保证良好的孔隙堵塞效果。微泡尺寸增长速率及静态析出实验中液体析出速率可作为评价微泡稳定性的指标:微泡尺寸随时间增加增长缓慢且寿命较长,静态析出实验中液体析出速率低,说明微泡钻井液具有良好的稳定性。图6表8参16
In view of the successful application of microbubble drilling fluid in depleted reservoirs, the rheological properties and the stability of the microbubble drilling fluid were studied through experimental and data analysis. A typical microbubble drilling fluid was prepared and its viscosity was tested at different temperatures. The power law model, the Bingham plastic model and the Herschel-Bulkley model were used to fit the test data respectively. It was found that the Herschel-Bulkley model Can accurately describe the rheological properties of drilling fluid before and after the formation of microbubbles at different temperatures. According to the Herschel-Bulkley model fitting results, the increase of temperature will increase the shear dilution of microbubble drilling fluid, the static shear force of drilling fluid and the purifying ability of wellbore after the formation of microbubbles increase, and the performance of microbubble drilling fluid at high temperature Will not be significantly weakened. Microbubble drilling fluid has high viscosity at low shear rate, which can ensure good pore plugging effect. The growth rate of the microbubbles and the liquid deposition rate in the static precipitation experiment can be used as an index to evaluate the stability of the microbubbles: the size of the microbubbles grows slowly and has a longer life span with the increase of the time, and the liquid deposition rate in the static precipitation experiment is low, indicating that the microbubble drilling fluid Has good stability. Figure 6 Table 8 Reference 16