表层开窗侧钻时聚合物黏弹性对钻井液携带能力的影响

在开窗作业过程中产生的铁屑，因为其密度高，在环空中下沉速率较快，同时这些铁屑形状各异，在被钻井液携带上返时容易互相缠绕形成笼状，进一步增加井眼的清洁难度。通过室内动态携带效率模拟评价设备，比较了不同聚合物溶液在不同浓度下对铁屑的携带能力。结果表明，随着聚合物流体弹性应力的增大，使得环空中流体在层流时的法应力也随之增大，钻屑或铁屑在被携带上返时出现黏壁的现象愈发明显，也会在一定程度上降低钻井液的携带效率。因此，聚合物流体的黏弹性在一定范围内对流体的携带能力有正面影响，但超过这个范围就要考虑其产生的副作用对携带能力的削弱。 

Viscoelasticity of Polymers and Carrying Capacity of Drilling Fluids When Sidetracking through Surface Casing

Through-casing sidetracking is one of the important technical methods for production and efficiency enhancement. When opening windows on the walls a several layers of casing strings, large quantities of iron fillings are produced, imposing a challenge to the hole cleaning capacity of the drilling fluid used. The iron fillings produced in the windowing operation have high density and are therefore settling fast in the drilling fluid. Meanwhile, the iron fillings have different shapes, when carried up the annular space they tend to intertwine with each other to form cage-shaped structures, further increasing the difficulty of borehole cleaning. Several polymer solutions, each with different concentrations of the same polymer, have been evaluated on a laboratory dynamic carrying efficiency tester for their ability to carry the iron fillings. Through these tests, the rheological property of the polymer solutions affecting the carrying of the iron fillings during window-opening operation was studied from the viscoelasticity aspect of these polymers.