Numerical simulation and experimental study on gas lift slag removal in long borehole for bedding gas drainage

Abstract

The difficulties of gas lift slag removal and the accidents caused by sticking drill, holding drill and even jet hole are always the important factors that baffle gas extraction technology of long boreholes along the bedding. In this paper, the numerical simulation and field test are used to study the numerical simulation test of gas lift slag removal in long borehole of bedding gas drainage. It is found that when the particle size of coal cuttings is small, the air volume and chip production are the main factors of coal cuttings deposition, while when the particle size of coal cuttings is large, the coal cuttings deposition is affected by air volume, drill pipe speed and chip production; when the air volume is 500 m3/h, the rotating speed of the drill pipe needs to exceed 80 r/min to ensure effective slag removal, while when the air volume is 400 m3/h and 300 m3/h respectively, the rotating speed of the drill pipe needs to exceed 120 r/min and 200 r/min to ensure effective slag removal; in order to effectively discharge slag, the rotating speed of drill pipe should be kept at 80-120 r/min and the air volume should be more than 400 m3/h.

Keywords

• gas lift slag removal
• gas drainage
• bedding long borehole
• coal cuttings deposition
• numerical simulation