Wire Wrapped Screens (WWS) have received more attention from Steam assisted Gravity Drainage (SAGD) operators. A WWS is commonly fabricated with a wedge-shaped wire that is spiral-wound around a perforated base pipe to form a Wire wound Mesh (WWM). This produces a single, continuous, keystone-shaped helical slot with a large open flow area to enable for fluid flow while maintaining the structural rigidity of the base pipe and providing sand control to the wellbore.
The structural integrity of a WWS with dual ring Wrap-On-Pipe (WOP) WWM and gap opening and closing within the WWM during thermally-induced loading were assessed through a full-scale thermal test program and Finite Element Analysis (FEA), during which the WWS was subjected to thermal cycle loading between 20°C (68°F) (room temperature) and 280°C (536°F), simulating the target temperature of a relatively high-temperature SAGD project in northern Alberta. The loading condition selected as the worst-case scenario from a service limit state perspective for the testing and FEA was to enable the WWS specimens to freely expand during the initial heating phase and then axially constrain them for the subsequent thermal cycle loading. This loading condition was selected because it was the scenario most likely to cause gap width opening between the wire wraps to an extent where the WWS could no longer provide suitable sand exclusion.
The FEA was used to determine the peak plastic strains within the base pipe and the effect that the residual stresses, introduced by the welding process, have on the structural integrity of the WWS. The frictional conditions between the spiral-wound wire and base pipe were found to have a significant impact on limiting axial movement between the WWM and base pipe, and the axial strains developed in the screen. In addition, an analytical model is presented that estimates the gap opening of the WWM because of thermal strains, which compared well to the results obtained through FEA.
The testing was conducted to assess the structural capacity of the WWS design and monitor change in gap widths during thermal cycling at key structural locations of the WWS design. The strain monitoring results from the full-scale test program were found to be consistent with the predicted strains from the FEA assessment.
This paper presents testing and FEA results for a WWS with WOP WWM, and investigates the potential of a WWS to provide long-term and reliable sand control for SAGD wells.