小井眼环空循环压耗计算

小井眼钻井的技术关键是环空水力学。小井眼钻具外径与内径之比较大,环空间隙较小,引起环空压耗、钻井液流变性发生较大变化,许多常规钻井中可忽略的因素在小井眼中却显得尤为重要。用Her-schel-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,导出了计算小井眼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。

Calculation of circulating pressure loss in annular of slim hole

Annular hydraulics is the key of slim hole drilling technology. The external and internal diameter ratio of slim hole drilling tool is relatively large and annular space is relatively small, resulting in large variation of annular pressure loss and rheological properties of drilling fluids. Many factors that are negligible in conventional drilling operation become very important in slim hole drilling. Herschel - Bulkley mode is used to describe the rheological properties of drilling fluids. An annular circulating pressure loss model of slim hole is built taking consideration of the influences of drill string decentralization and rotation on flow of drilling fluids in annular and drilling string. Comparison of model results with the conventional calculation results and measured data shows that this model has relatively high accuracy and can meet the requirements of field operation.