Abstract: Addressing the issue of sand-induced wellbore plugging leading to elevated pressure drop in loose sandstone reservoirs,53 near-well sand-control zone pressure drop tests were conducted to evaluate the evolution of pressure drop in three sand-control zones:the wire-wrapped screen section,the gravel-pack annular section, and the fracture section.Results indicated significant differences among these zones:in the screen section, initial pressure drop was small(0.002-0.016 MPa)but rose rapidly to 0.200-3.000 MPa as particles gradually clogged the screen and outer annulus;in the gravel-pack section,initial pressure drop was only 0.002-0.030 MPa but could increase up to 50-fold under sustained sand intrusion;in the fracture section,wider fracture widths yielded lower pressure drops,and for a conventional ceramic proppant pack the pressure drop was lowest-only 60% and 96% of that in the hydrophobic ceramic and quartz sand packs,respectively.Combining these results,it is recommend that in the screen zone fine sand be released early in production to allow coarse sand to accumulate first and establish stable channels,and that 0.200 mm precision screens be used.In the gravel-pack zone,the gravel size should be reasonably matched,and coated sand should be preferred to enhance blockage resistance.In the fracture zone,propped fractures wider than 20 mm with large-particle conventional ceramic proppant are recommended to effectively reduce near-well pressure differentials.These findings provide technical support for optimizing sand-control processes and low-pressure development.

Key words: loose sandstone reservoir, screen zone, annular pack zone, fracture zone, sand-control region, pressure drop