A Review of Screen Selection for Standalone Applications and a New Methodology

Abstract

Summary Standalone screens (SASs) in open hole can provide highly reliable sand-control completions at a lower cost and with less operational complexity than other openhole sand-control completions and can provide long-term productivity performance comparable to other openhole completions when applied in the "right environment with the right procedures." Although many in the industry would agree with the preceding statement, there is no consensus on what the right environment is and what the right procedures are. Even when there is agreement on the applicability of SASs for a particular sand-size distribution, there are considerable differences in the recommended screen type and screen opening between various laboratories. In this paper, we critically review the various laboratory testing procedures used in the industry and the interpretations made to evaluate screen performance and screen selection for SAS applications. We demonstrate that the way some of the laboratory tests are performed makes them biased toward one type of screen (wire wrap) and that some are interpreted without sufficient information such that they almost always favor another type of screen (premium mesh). We show that severe screen plugging with clean formation sand is almost never an issue and that the probability of screen plugging because of other factors can be minimized when proper precautions are taken. We propose that candidates for SAS applications be initially selected on the basis of sand-retention performance, with the final selection confirmed on the basis of screen/sand pack permeability measurements. In addition, on the basis of approximately 185 laboratory tests performed on various types of wire-wrap (6 to 16 gauge) and premium mesh (60 to 600 μm) screens for unconsolidated sands and using a set criterion for sand retention, we conclude that many of the currently used criteria in the industry for selection between gravel packing and SAS are highly conservative and unduly limit the possible application of SASs.