计算窄间隙环空循环压耗的新模型

影响窄环空中摩擦压降的关键因素为环空尺寸的变化、钻柱旋转及偏心。用Herschel—Bulkley模式描述钻井液的流变性，考虑钻柱偏心和旋转对钻井液在环空和钻柱内流动的影响，提出了一种新的计算窄间隙环空循环压耗的模型，将所建立模型和传统方法的计算结果与实测数据比较表明，该模型具有较高的精度，可以满足现场作业的要求。

A Novel Model of Calculating Circulating Frictional Pressure Loss in Narrow Annuli

Frictional pressure loss calculations in narrow annuli of slim-hole and coiled tubing operations require more accuracy than before .The key factor of effecting frictional pressure loss in narrow annuli is variable annular dimensions ,rotation and vibration of drill string.On the basis of describing the rheological property of drilling fluid by Herschel Bulkley model and in consideration of the influence of the drillstem eccentricity and rotation on the drilling fluid flowing in annular space and drilling string ,a novel hydraulic model of calculating circulating pressure loss is put forward in the paper .Through comparing the results calculated with those measured ,it is shown that this model has higher accuracy and may meet a demand for on-site drilling operation.