No abstract

Separate layer water injection technic is one of the efficient measures for keeping petroleum output steady and improving oil recovery rate. In the actual operating mode, injection string which be placed in the three-dimensional wellbore may produce complicated stress and strain. Analyzing mechanical property in different conditions accurately is very important for improving design level of string and success rate of separate layer injection. Considered wellbore curvature and spatial stress status, a three-dimension mechanical analysis model of layer water injection string was established which analyzed the comprehensive influence of injection tools such as packer, water distributor, centering guide, and the mechanical continuity conditions of injection tools were established. Based on the mechanical model, considering the influence of working parameter, a mechanics behavior analysis method and procedure were proposed in the whole process of the separate injection pipe strings. In addition, the mechanical analysis software was developed using C#, which the research production had been successfully used in Huabei Oilfield. 。

In the beam pumping system, the broken valve cover of the oil well pump frequently leads to oil well failure. This paper examined the alternating load of the oil well pump valve cover and predicted its fatigue life. First, the fluid–structure coupling simulation model of valve ball motion was established through the fluid dynamics simulation software Fluent to investigate the velocity of the valve ball impacting the valve cover. Based on the simulation results about the impact velocity of the valve ball, the mechanical model of the valve ball impacting the valve cover was constructed through ANSYS/LS-DYNA software, and the impact stress and change rule of the valve cover were analyzed. Then, the S-N fatigue curve of the common material of the valve cover was experimentally obtained. Based on the impact stress simulation results of the valve cover and the fatigue curve of the common material of the valve cover, the modified Miner’s Rule was applied to evaluate the fatigue life of the oil well pump valve cover. The results showed that the impact stress of the valve cover was positively related to the impact velocity of the valve ball, and the fatigue life of the 17-4 PH valve cover was longer than that of other materials. The above results not only provide a theoretical basis for the performance improvement and material selection of the valve cover but also contribute to the optimization of production parameters of the oil well.