高压高产气井屈曲管柱冲蚀损伤机理研究

Erosion damage mechanism of buckled tubing in high pressure and high production gas wells

天然气在油管内高速流动对管柱造成冲蚀损伤,严重威胁气井生产和作业的安全。装有封隔器的管柱在井下各载荷作用下易发生屈曲变形,此时高压气体对管柱的冲蚀作用将更加严重,易造成井下管柱失效甚至井场事故。为此,根据发生屈曲后正弦弯曲和螺旋弯曲管柱内流道特点,以天然气流体动力学理论为基础,针对克拉2气田一口高压高产气井建立了油管的计算流体动力学模型(CFD模型)和气井出砂时砂粒对屈曲油管的冲蚀模型。对天然气在螺旋弯曲和正弦弯曲流道内流动规律进行了数值模拟,研究了砂粒对油管内壁的冲蚀速度和剪切力,得到天然气对弯曲油管的作用力以及屈曲管柱内的冲蚀规律,为实时准确地预测高产气井管柱的冲蚀损伤状态提供了依据,为管柱冲蚀损伤预防措施的提出提供了理论基础。

The high-speed gas flow in tubing causes erosion damage to the string for high pressure and high production gas wells, and the erosion threats the security of gas production and operation seriously. The tubing string with packers tends to be buckled, making the erosion more damaging, which is prone to cause downhole string failure or even well field accidents. Therefore, considering the flow channel features in the tubing string of sine buckling and helical buckling, based on the theory of the natural gas flowing dynamics, the CFD model and sand erosion model were established for a high pressure and high production gas well in Kela 2 gas field. Numeri- cal simulation was conducted on the flow performance of natural gas in sine and helical buckled tubing string, and the erosion velocity and shear stress of sand flowing in the tubing was studied. The force and erosion law of natural gas to buckled tubing were obtained. It provided a reference for real-time prediction of erosion damage in high pressure and high production gas wells, and a theoretical basis for the proposal of erosion damage prevention measures.