气体钻水平井井筒两层流动机理研究

Two Layer Flow Mechanism of Horizontal Wells in Gas Drilling

目前关于气体钻水平井的理论研究大都集中在最小注气量的选择上;而对气体钻水平井水平段井筒内的多相流动的机理缺乏深入的理论研究。在研究水平井段多相流动机理的基础上,应用气固两相流动力学理论,结合扩散理论,建立了适合气体钻水平井水平井段两层流动的理论模型,即上层悬浮层、下层为滑动床流动。根据现场某井数据进行了实例计算结果表明:气体钻水平井井筒携岩的最优速度应大于岩屑的沉降速度;岩屑稳定输送的条件为水平井井筒环空内为分层稳定流动;沿程阻力在低速主要来自于底层滑动床中岩屑颗粒与井壁之间的摩擦阻力,高速区来自于悬浮层内岩屑与井壁之间的摩擦阻力。最后结合计算结果,对比前人在水平气固流动中的实验结果,对气体钻水平井的最优注气量、井筒压降计算等给出了合理的建议。

At present, the gas drilling horizontal wells theoretical studies mostly concentrated in the smallest injection volume of choice, while the wellbore multiphase flow mechanism of the gas drilling horizontal well lack lacks depth theoretical study. The two layers flow at the horizontal well of gas drilling wells based on gas drilling horizontal wells solid flow characteristics analysis, application phase flow theory, diffusion theory, namely upper suspending layer, the lower sliding bed. According to the data from a well, the optimal gas injection volume should be greater than settling velocity, stratified steady flow is conditions that the cuttings transport stability in the horizontal wellbore annulus. The resistance consists of the friction between the sliding bed and the well-wall at slow-speed zones, the resistance consists of the friction between the cutting of the suspension layer and the well-wall at high- speed zones. Finally, combine the results, compared to previous levels of gas-solid flow in the experimental results, a reasonable proposal is given how to calculate the optimal gas volume and pressure drop gas drilling horizontal wells for the gas drilling horizontal wells.