Design And Analysis Of Constant Pressure Throttle Valve For Natural Gas Wells

As a kind of clean energy, the nature gas plays a more and more important role in the world's energy system, and the demanding and production of it is increasing at the same time. While there still have some problems in the gas exploitation process, for example, the pressure of natural gas in gas well is usually too high to be used directly on the equipments on the ground. In order to ensure the well-function of the equipments, the pressure of natural gas needs to be reduced before it translated to gas gathering station. The most commonly used method is throttling, which can be divided into two methods, the ground throttling method and the down-hole throttling method. Comparing to the ground throttling method, down-hole throttling is more economical, because it can take advantage of the formation heat to heat natural gas and so to prevent the formation of gas hydrate. In recent years, the down-hole throttling technology has applied successfully in many gas fields both at home and abroad. The most commonly used down-hole throttle valve is choke, with a fixed size, while the operation of it is complicated and time-consuming, especially when the pressure under well somehow changes or the production of gas well needs to be adjusted.To solve the problem above, this paper made some research on the following aspects of down-hole throttle valve, based on the theory of down-hole throttling:(1) Designed a down-hole throttling valve of constant pressure for gas well, including the overall structure and concrete structure size of the throttle valve. The down-hole throttle valve can change the throttle opening size automatically according to the change of inlet pressure, which can make sure that the outlet pressure of throttle valve is in the designed area basically.(2) Carried out numerical simulations of the designed throttling valve, including the pressure, velocity and temperature of the flow field under different throttle opening size, the fluid-structure interaction of throttle valve, the erosion of valve core and valve seat in two phase flow gas-solid.(3) Optimized the throttle valve core, valve seat structure and spring, based on the results of numerical simulation. The erosion degree on throttle valve of different seat shapes is considered. The ability of the spring is also considered when the fluid acts on the entire cone of the valve.The down-hole throttle valve for gas well designed in this paper can enhance the production efficiency and reduce the exploitation cost of natural gas. The perfection and wide promotion of the product has important meaning, both practical and economical.