库车山前低返速固井钻井液低剪切流变特性研究

针对塔里木库车山前超高压气井四开低返速固井过程中钻井液实际处于低剪切流动状态和现场采用全剪切速率流变测试数据拟合其流变模式和流变参数的不足，研究了库车山前钻井液在低返速固井过程中的低剪切速率范围、对应的流变模式和流变参数及其对注水泥环空流动摩阻系数的影响。研究结果表明，在低返速固井过程中，钻井液的剪切速率明显小于1022 s?1（600 r/min），且对应的流变模式及流变参数与全剪切速率范围内的差异巨大，导致基于二者的注水泥环空摩阻系数也存在较大的差异，从而影响对注水泥环空压力计算的精确控制。为此，对低返速固井，应根据其低剪切速率范围内的流变模式和流变参数计算环空流动压耗，控制固井排量，提高低返速防漏固井的成功率。 

Research for low shear rheological properties of low return velocity cementing drilling fluid in Kuqa Piedmont

In view of the fact that the drilling fluid is in the low shear flow state during the fourth spud in ultra-high pressure gas well in Kuqa mountain front of Tarim Basin, the rheological model and rheological parameters of the drilling fluid were fitted by the rheological test data of the full shear rate. The low shear rate range, corresponding rheological mode and rheological parameters of the drilling fluid and its effect on the cementing annulus were studied The influence of flow friction coefficient. The results show that the shear rate of drilling fluid is obviously less than 1022 s?1 (600 r/min) in the process of cementing with low return velocity, and the corresponding rheological mode and rheological parameters are greatly different from the range of full shear rate, which leads to a certain or even large difference in the friction coefficient of cement injection annulus, which affects the accurate control of the calculation of cementing annulus pressure, For low return velocity cementing, the annular flow pressure loss should be calculated according to the rheological mode and rheological parameters within the low shear rate range, the cementing displacement should be controlled, and the success rate of low return velocity and leak proof cementing should be improved.