Failure mechanism and structure optimization of sand control screen in water-bearing gas well

The prospect of natural gas reservoir is broad. As the mining channel, the state of gas well determines the mining efficiency of the whole natural gas reservoir. After long-term mining of gas wells, the problem of water production will lead to the destruction of sand control screens, resulting in a large amount of sand production, which seriously endangers the safe production of gas wells. The “punched seam sleeves (PSS) + metal woven meshes (MWM)” is the main sand control structure, which failure mechanism needs to be explored. In this study, based on the erosion and corrosion environment, a simulation test with water content and gas production rate as single factor variables was designed. The dynamic grid layer laying method was used to simulate the corrosion environment, and the influence of erosion wear on sand control failure of screen pipe in water-bearing gas well under corrosive environment is analyzed. Through multi-factor comparison and evaluation, the structure of the screen pipe was optimized. The results show that when the water content increases from 0.5% to 7%, the maximum erosion rate of the PSS increases first and then decreases, reaching a maximum value of 5.341 × 10⁻⁵ kg/(m²·s) when the water content is 2%. The maximum erosion rate of MWM is linearly positively correlated with the water content. When the gas production rate increases from 3 to 10 m/s, the maximum erosion wear of defects increases from 5.108 × 10⁻⁷ to 1.247 × 10⁻⁵ kg/m², and the maximum erosion wear of MWM increases from 4.728 × 10⁻⁸ to 1.743 × 10⁻⁶ kg/m². Through orthogonal experimental analysis, it is found that the velocity has a significant effect on the erosion of the PSS. Based on this, the inlet and outlet flow channels of the screen pipe are optimized. The maximum erosion rate of the optimized PSS model is reduced by 25.7%, and the maximum erosion rate of MWM is reduced by 19.7%. The water-bearing gas well should properly control the mining speed at the initial stage of mining, and then increase after the formation of a stable sand bridge, and reduce the concentrated erosion caused by the drag force by optimizing the width of the inlet and outlet of the flow channel, which can effectively improve the service life of the screen pipe of the water-bearing gas well.