水平井段脉冲携岩数值模拟研究

水平井钻井技术已成为现代油气勘探开发的重要手段，水平井段岩屑运移不畅造成钻井过程中的高摩阻和扭矩、卡钻和憋泵等情况，影响钻具的使用寿命和钻进安全，特别是使用现有的常规携岩方法无法解决，为此，提出脉冲携岩方法。在现有水力脉冲的基础上，根据分流继能机理，建立小井眼水平井岩屑运移的流场模型，采用RNG k-ε模型、幂律模式及二次开发子程序进行数值计算，确定脉冲携岩合理的脉冲周期、占空比等参数，并研究水力脉冲条件下钻井液排量、偏心度、岩屑粒径等参数对偏心环空岩屑运移的影响，得到环空岩屑运移速度和浓度的分布规律。研究表明，在同等条件下，脉冲携岩效率更高，破坏岩屑床效果更好，降低岩屑床浓度约40%。

Numerical Simulation of Cuttings Pulse Carrying in a Horizontal Well

Horizontal well drilling technology has become an important means of modern oil and gas exploration and development. It can cause some dangerous accidents, such as high friction and torque, stuck pipe and choke pumps, when the annulus transportation condition of horizontal well is poor. And the accidents will impact the life of drilling tools and the safety of drilling progress, which cannot be solved in conventional technology. So, the method of pulse carrying cuttings is extremely needed. On the basis of the existing hydraulic pulse and the following diversion mechanism, a slimhole horizontal well flow model is established. It uses RNG k-ε model, the power-law model and the secondary development of subroutines for numerical calculations to determine reasonable pulse cycle of pulse carrying rocks, duty cycle, and other parameters. In order to find the distribution law of the velocity and density of cuttings it also discusses the effect of the flow rate of drilling fluid, the eccentricity of drilling pipe and the diameter of cuttings. The results show that under the same condition, pulse carrying cuttings is more efficient, destroying cuttings better and reducing cuttings bed concentration by about 40%.