小井眼侧钻水平井波动压力计算模型

MODEL FOR COMPUTING SURGE AND SWAB PRESSURES IN SLIM AND HORIZONTAL HOLES

石油钻井过程中，准确确定起下钻引起的波动压力是保持井下压力平衡、防止井下复杂事故的发生和实施近平衡钻井的关键。随着近年来小井眼水平井钻井技术的不断应用，迫切需要解决钻小井眼水平井时的波动压力的计算问题。文中根据小井眼水平井的特点，用Ｈ－Ｂ模式描述钻井液的流变性，从流体运动的基本方程出发，建立起了小井眼侧钻水平井的波动压力计算模式。实例计算表明，该模式是可靠的，且具有较高的计算精度，完全可以用于小井眼侧钻水平井的钻井设计和施工。

Drilling practice and study show that the surge and swab pressures (SSP) caused by running or pulling a pipe in the wellbore are one of the important causes leading to lost circulation, kicks and other wellbore accidents in the process of oil drilling. So the accurate determination of SSP is the key to controlling pressure balance, preventing possible accidents and thus succeeding in balanced drilling. With the increasingly widespread use of slim and horizontal hole (SAHH) drilling technology, new methods of determining SSP are urgently needed. This paper presents a new calculation model, in which the rheology of drilling fluid is described by H-B model, to determine the SSP of SAHHs. A comparison between the test data and predicted results indicates that the model is reliable and has a high level of accuracy, and thus can be used in the design and operation of SAHHs.