小井眼环空水力学评述

COMMENTARY ON ANNULUS HYDRAULICS IN SLIM HOLE

李少池 周煜辉

Li Shaochi Zhou Yuhui

总公司石油勘探开发科学研究院

讨论了小井眼环空水力学中的环空压耗的理论及其主要影响因素,导出了环空压耗的具体表达式,描述了库特流、戴劳旋涡和戴劳数等流变模式,钻具的各种运动形式,钻井液粘滞性及流变性对环空压耗的影响。小开眼钻具外径与内径之比(k值)较大,环空间隙较小,引起环空压耗、钻井液流变性、流态发生较大变化,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。

The theory of pressure drop in annulus and its affecting factors were described in this paper. The different equations of annular pressure drop related with these above mentioned factors were deduced. Some flow patterns as Coutte Flow, Dylaw Vertex and Dylaw Value were described. Different types of drill string movement, influences of drilling fluid rheology and viscosity on annulus pressure drop were interpreted. The paper demonstrated that substantial changes of pressure drop, drilling fluid rheology and drilling fluid flow pattern occur because of the greater ratio of Do/Di of the drill string and minor radial width of the annulus in slim well. Some factors which can be ignored in ordinary well drilling appear particularly important in slim well drilling.

10.3969/j.issn.1000-7393.1997.05.006