Factors Governing the Predicted Performance of Multilayered Metal-Mesh Screens

Abstract

Summary Multilayered metal-mesh screens (MMSs) are widely used as standalone screens for sand control in unconsolidated formations. The nominal rating of such screens is usually determined on the basis of the specifications of the filter layer. It is often found that screens with the same filter-layer nominal rating perform differently. It is shown in this study that the primary reason for this is that the sand-retention performance of multilayered MMSs is a strong function of not only the filter layer but also the protection and the support layers. This paper presents a systematic study that shows how the overlap between different mesh layers, the alignment of the protection and support layers, and the relative pore-size ratio, defined as the ratio of pore size of the protection/support layer to that of the filter layer, have a large impact on the sand-retention performance of an MMS. The pore-size distribution (PoSD) of multilayered plain-square-mesh (PSM) and plain-Dutch-weave (PDW) screens is calculated with a novel numerical technique. Influences of screen sintering, coupon sampling, and screen designs on the PoSD of a screen are modeled by varying the layer overlap, shifting the layer alignment, and modifying the design of the protection and support layers. The PoSD data are used as an input into an analytical model for evaluating sand production of PSM screens in slurry-type sand-retention tests (SRTs) for screen-design optimization. For PSM screens, the results show that the PoSD of a multilayered screen can be very different from the PoSD of the filter layer. In general, a decrease in sand production with an increase in layer overlap is observed; the trend exists irrespective of how mesh layers are aligned. A change in mesh alignment is found to cause a variation in sand production even with the same filter-layer pore size and layer overlap. The nominal rating of the filter layer of a multilayered PSM screen should be used to estimate sand production only when the pore sizes of the protection and support layers are much larger than the pore size of the filter layer. For PDW screens, layer overlap is shown to dominate the screen performance by affecting the filter-layer pore size. The PoSD of a PDW screen is found to be less affected by variations in layer alignment and relative pore-size ratio. This study clearly shows that the layer overlap, layer alignment, and relative pore-size ratio between mesh layers can have a significant impact on the sand-retention performance of a multilayered MMS. As such, widely different screen performances can be expected for screens with the same nominal screen rating. Our results have a direct bearing on how MMSs are manufactured, selected, and specified. Increasing the relative pore-size ratio appears to be a promising screen-design approach for obtaining consistent screen performance for multilayered MMSs.