Experimental and numerical simulation research on sealing performance and drainage efficiency of different types of plungers

In the middle and late stages of a gas well, the plunger gas lift process is an important means of drainage and gas production. We studied the liquid-drainage efficacy of different types of plungers (cylindrical plunger, brush plunger, and gasketed plunger) under different gas volumes and sealing differences. During the actual application in the field, the plunger has its specific size, on this foundation, a three-dimensional flow field model was created based on the actual tubing and plunger sizes, and the fluid loss and liquid-drainage process of various types of plungers was numerically simulated using the volume of fluid computational fluid dynamics numerical simulation method. The sealing mechanism of various types of plungers, as well as the impact of different gap widths between the plunger and the tubing wall on the plunger's sealing performance, were investigated. The gasketed plunger has the best sealing performance, followed by the brush plunger, and the cylindrical plunger has the worst sealing performance. The minimum gap width between the plunger and the tubing wall is an important factor affecting the plunger sealing performance; the smaller the gap width, the better the plunger's sealing performance. The experimental results show that the sealing performance is not the only condition for a reasonable plunger selection, and the size of the gas flow is also an important factor affecting the plunger's drainage. When the gas flow rate is small, the brush plunger has the best liquid-drainage efficacy, whereas the gasketed plunger has the best liquid-drainage efficacy under high gas flow.