State of the Art Screen Selection for Standalone Screen Applications

摘要

Standalone screens (SAS) in openhole can provide highly reliable sand control completions at a lower cost and with less operational complexity than other openhole sand control completions as well as 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 SAS 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 are biased towards one type of screen (wire wrap) and 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 due to other factors can be minimized when proper precautions are taken. We propose that screen candidates for standalone screen applications be initially selected based on sand retention performance, with the final selection confirmed based on flow capacity. In addition, based on 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 standalone screens.