【作者】 周卫东；

【导师】 沈忠厚； 王瑞和；

【作者基本信息】 中国石油大学 ， 油气井工程， 2008， 博士

【摘要】 本文针对高压射流钻井技术发展的需要,设计了离心式井底增压系统。该系统由涡轮动力单元、离心固液分离单元、离心增压单元和高低压双流道单元等四部分串联而成,即通过钻井液驱动涡轮旋转,带动固液分离装置和离心增压装置,使部分经固液分离的清洁钻井液,经增压后通过高低压双流道单元的高压流道进入钻头高压喷嘴,达到提高井底射流压力和速度,从而提高钻井速度、降低钻井成本的目的。以优选涡轮叶片型线为核心,在对传统叶片型线分析的基础上,采用了单型线且具有连续三阶导数的型线设计模型,避免了叶片后缘附近脱流现象的发生,保证了叶片表面速度和压力分布的平滑变化,提高了涡轮的效率,形成了一套高速涡轮叶片造型设计的新方法。同时,采用雷诺时均方程并结合改进型的RNGk ?ε湍流模型对涡轮马达进行了内部流动的全三维数值模拟,避免了模拟过程中需要考虑涡轮间隙泄漏的问题,并根据数值模拟结果对高速涡轮设计进行了改进。基于对高速多级离心泵复杂结构的分析,建立了通过VB编程与Pro/E相结合,利用Beizer曲线对高速多级离心泵叶片进行参数化造型设计的新方法,并成功开发了高速多级离心泵设计CAD软件。应用本文开发的设计软件,结合油田钻井生产实际条件,设计出了由112级叶导轮组成的井底增压系统的高速多级离心泵。首次对不同流量工况下五级离心泵的总体特性以及内部流动特征进行了全三维流动数值模拟,并对离心泵各级叶导轮的子特性以及流动特征进行了详细研究,着重分析了各级叶导轮在性能、子午平均流动参数以及三维参数分布上的异同。数值模拟结果表明,除第一级泵级内流场有其特殊的流动规律外,以后各级泵级内的流动特性都具有很好的一致性。因此,可以认为选取三级泵级的计算域进行特性及流动特征的模拟,便可以准确的对整机性能进行分析,从而使整机离心泵的数值模拟得以大大简化。实验研究支持了理论分析,结果表明在现有钻井条件下,在27.3L/s的排量和4200rpm转速下,通过本文研制的第一代井底增压系统,可使涡轮产生273N.m的扭矩,118.8KW的输出功率,整机效率为59.8%;高速多级离心泵在输入115KW的轴功率,260.95N.m的扭矩下,其输出压力增值可达26.1MPa左右,总效率可达61.2%,可使钻头高压喷嘴压降达到36MPa以上,从而为井底增压钻井技术的发展提供了一条新的技术支撑。更多还原

【Abstract】 In order to meet the requirement of high-pressure water jet drilling technology, a downhole centrifugal supercharging system, which consists of turbo-power unit, fluid-solid centrifugal separating unit, centrifugal supercharging unit and double flow channels unit, is present in this thesis. Turbine is drived by the drilling fluid which propels both the fluid-solid separating unit and the centrifugal supercharging unit. Clean drilling fluid from the separating unit is supercharged and enters the high-pressure flow channel and in the end, the high-pressure nozzle in the bit which increases the bottomhole jet pressure and velocity, and moreover, increases the drilling rate and lowers the drilling cost.Based on the analyses of traditional blade molded lines, with the core of optimizing the turbine blade molded lines in mind, a new design method for the high-speed turbine blades molding is present in this thesis with the characteristics of molded line models up to continuous three-order derivatives, avoidance of the flow separation near the rear of the blades, smooth changes of the velocity and pressure on the blade surface and high efficiency of the turbine. Moreover, numerical simulation is performed on the internal flow inside the turbine motor with Reynolds-averaged equations and modified RNGk ?εturbulence model which eliminates the leakage problem and optimizes the high-speed turbine design.On the basis of previous analyses of complex structure of the multistage high-speed centrifugal pump, a new method combining Visual Basic and Pro/Engineer is present applying the Beizer curve to the parametric design of multistage high-speed centrifugal pump blades and a CAD software is also released. A high-speed centrifugal pump with 112 stages is created with the CAD software together with the physical condition of drilling engineering.A full three-dimensional numerical simulation of internal flow and bulk performance of a 5-stage centrifugal pump is performed with emphases on the flow details of each stage, for example, the performance of each impeller and pulley, meridian-plane-averaged flow parameters and parameter distributions on three dimensions. Numerical results show that good conformance of flow characteristics is found among the stages except the first stage which proves that computational domain of three stages is enough to reveal the full information needed about the whole prototype.Experimental results fully support the theoretical analysis which shows that under current drilling condition, the centrifugal supercharging system invented in this thesis can produce torque up to 273N.m, output power of 118.8kw and bulk performance of 59.8%. The output pressure increment up to 26.1MPa, the bulk performance of 61.2% and nozzle pressure drop up to 36MPa can achieved with such a centrifugal pump under the condition of 115kw shaft power and 260.95N.m torque, which provides a new technical support for the development of downhole supercharging drilling technology.更多还原