Unraveling the Myths Associated With Selecting Standalone Screens and a New Methodology for Sand-Control Applications

Many completion engineers use laboratory sand-retention testing as a tool toselect a screen for standalone sand-control applications, some focusing onprepack and others on slurry testing. Those who use slurry tests for screenselection typically do so on the basis of the conventional wisdom that slurrytesting is more challenging; thus, it represents the worst-case scenario forsand production. Furthermore, the general belief in the industry has been thatmetal-mesh screens with a "pore structure" are better for sand retentioncompared with wire-wrap screens (WWSs) of slot geometry, although they are moreprone to "plugging." These are just a few of the many myths that exist inscreen selection for standalone screen (SAS) applications. Recent papers on themodeling of sand retention by screens of various geometries, and supported bylaboratory experiments, provided the tools for predicting sand production inboth prepack and slurry conditions, as well as allowing for a systematicperformance comparison of various screens by use of the entire particle- sizedistribution (PSD) of formation sands (Mondal et al. 2011 and 2012; Chanpura etal. 2012, 2013). In this paper, we discuss and challenge many myths in thescreen selection for SAS applications and substantiate our findings withmodeling and experimental data. The conditions under which a slurry or aprepack test would be more conservative are identified, highlighting themechanisms of sand retention (size exclusion or bridging dominated). Wedemonstrate that the current thinking that prepack tests are always moreconservative from a sand-production standpoint is incorrect. We also show thatthe concept that metal-mesh screens are always superior for sand retention thanWWSs is incorrect, highlighting the factors that affect sand production throughvarious screens [e.g., open flow area (OFA), wire thickness, and fraction ofbridging-sized particles in the formation sand]. Finally, a methodology forscreen selection in SAS applications is proposed.