Authors: Fattahpour, Vahidoddin & Mahmoudi, Mahdi & Nouri, Alireza & Leitch, Michael.
Several sand control techniques have been used in SAGD wells in Western Canada. For most projects, slotted liner has been the sand control of choice for its economics, ease of use, and acceptable performance. Careful design of the slot geometry is crucial to maintain long term wellbore performance but is not an easy task in formations with high fines content and other challenging characteristics, such as in Grand Rapids or shore-face at the upper member of McMurray. The objective in the design of sand control is generally to minimize the production of sand and maximize the retained permeability in the liner’s vicinity by allowing the production of any mobilized fines, avoiding extreme pressure drops by minimizing the curvature of flow streamlines around the slots, and avoiding the plugging of slots over time. Design practices for sand control in SAGD wells are currently based mostly on Particle Size Distribution (PSD) and the fines (<44um) content. Where designers focus principally on retaining sand rather than maximizing the retained permeability in the liner’s vicinity, there is an increased risk of underperforming completion designs, but long term well performance requires a reasonable tolerance for solids production. This paper provides a critical review of existing design criteria and the experimental testing and techniques for assessing the sand control design for SAGD production wells. It reviews the mechanisms which cause sand production and fines migration in relation to the PSD of oil sands and the formation clay and silt content. In addition, the paper presents field failure cases from the literature and examines the common problems with different types of sand control. Finally, practical recommendations are presented to further improve the current design criteria and sand control experiments to achieve higher productivity index, lower skin buildup, and greater durability of sand control screens.
