Study on erosion wear mechanism of choke valves at outlet of ultra-high pressure sour natural gas wells

doi:10.16265/j.cnki.issn1003-3033.2022.03.008

Abstract

Abstract:

In order to ensure safe production and operation of ultra-high pressure sulfur-bearing natural gas wells, influencing factors of erosion wear rate were analyzed. Firstly, based on erosion wear theory and Fluent software, an erosion model was established by taking cage sleeve choke valves of natural gas wellheads with pressure above 70 MPa and H₂S volume content of 0-2% as an example. Then, motion track and wear mechanism of solid particles in the valves were studied and compared with actual situation. The results show that when these particles are in upstream straight pipe section of the valves, erosion wear can be ignored, but it will be the worst when they are at valve chamber wall directly opposite the 180° choke hole, and be mildly severe at downstream. The wear principle of lower half arc of valve cavity is secondary erosion, while semi-arc of straight section entrance and upper half arc of throttle valves are mostly micro cutting wear. It is also found that the higher the H₂S content and average flow rate are, the heavier erosion wear will be. Therefore, the flow rate of natural gas can be controlled within 331 m/s.

Key words: ultra-high pressure, sulfur-bearing natural gas, choke valve, erosion wear, motion track

JIA Wenlong, LI Xiaoyu, CHENG Tingting, LUO Zhaoqian, XU Jiashuang, HAN Xicheng. Study on erosion wear mechanism of choke valves at outlet of ultra-high pressure sour natural gas wells[J]. China Safety Science Journal, 2022, 32(3): 58-64.

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屈服强度/ MPa	腔内磨损情况	最大冲蚀磨损速率/ (10^-7kg·m^-2·s^-1)	平均冲蚀磨损速率/ (10^-7kg·m^-2·s^-1)
848	大多为均匀磨损	7.09	3.90
780	出现较多点蚀麻点	7.78	4.48
720	磨损面积、程度严重	8.24	5.04

节流小孔数量/个	腔内磨损情况	平均流速/ (m·s^-1)	平均磨损速率/ (kg·m^-2·s^-1)
10	轻微麻点磨损	215	1.8×10^-8
8	面积较小,基本为均匀磨损	260	2.62×10^-8
6	磨损较严重	354	3.41×10^-8
4	大面积磨损, 磨损严重	491	3.64×10^-8