Parametric Study on the Collapse Strength of Expandable Sand Screens

The problem of sand production in oil wells during oil extraction has seriously affected the stability and increase in oil and gas production. Despite the excellent sand control performance and technical advantages demonstrated by the expandable sand screen (ESS), its frequent collapse failure has disrupted the normal production of oil wells. Therefore, a systematic study on the collapse strength of the ESS was conducted. Through postexpansion tensile tests, the hardening law of 316L material under different expansion ratios was obtained. A three-dimensional finite-element model of the ESS was established. The influence of material hardening, nonuniform external pressure, and slot structure parameters on the collapse strength of the ESS was analyzed. The results show that (1) the higher the expansion rate of 316L material, the more significant the plastic hardening phenomenon becomes. By considering the plastic hardening of the material, waste can be avoided in the design and selection of the base pipe. (2) The pressure required for the slots of the expanded base pipe to close completely depends on the maximum external pressure and is not affected by the size of the pressure difference. The greater the degree of uniform external pressure, the faster the base pipe collapses, and the more severe the collapse becomes. (3) It is recommended that the slot length be designed as 100 mm. The slot width should be less than 5 mm, and it is recommended that the slot width be designed as 4 mm. The optimal slot arrangement is staggered slots. The research results can provide a theoretical basis for the structural optimization and collapse strength mechanism of expandable sand screens.