Innovative Sand-Control Screen Assembly Enables Successful Multi-Lobe Frac Packs in Adverse Recompletion Conditions

Abstract

Abstract Industry experience has shown that frac pack completions can provide effective production stimulation and reliable sand control for unconsolidated sand reservoirs. One of the more rewarding areas of opportunity is in the completion of longer and more complex intervals that can be stimulated with a single frac pack treatment. Here, the cost saving of a single completion versus the cost of two or the recovery of reserves from pay zone sand added to the completion interval can add significantly to the cash value of the well. This paper discusses an innovative screen that has a concentric shroud that can treat two separate and distinct sand lobes during a single frac-pack operation. Two cases histories illustrate the use of an innovative assembly that uses the new screen to enhance the stimulation and sand control results of frac pack completions on unconsolidated sand reservoirs with complex lithology and permeability contrast. The capabilities of this technology have brought a long-sought-after solution to fruition. Introduction Although conventional screens have been very successful in controlling sand production in most situations,1,2 not every well configuration lends itself to traditional screens. For example, in completions where there is a risk of screening-out in the upper part of the completion before the lower part of the completion, a screen-out with conventional screens can prevent the gravel slurry from reaching the lower part of the completion. Questionable applications include:frac packs where potential annular restriction or bridging may compromise sand control or uniform stimulation of the pay intervalfrac packs in intervals where there are distinct layers with different lithologyfrac packs in intervals where there are significant variations in permeability and porosityfrac packs in long intervals where there is concern that a complete annular pack would be achievedfrac packs in highly deviated intervals where multiple fracture initiation may jeopardize complete annular packing. Because of the more complex completions now attempted, the incidence of failures experienced in scenarios such as those listed above have increased. To provide a solution, a new type of sand-control screen assembly that consists of an outer perforated shroud placed over a metal-mesh sand screen has recently been developed. With this assembly, the annular space between the outer shroud and screen forms a secondary slurry flow path to enable bypassing a blockage in the outer annulus between the shroud and the casing. The perforations in the shroud are designed to balance slurry flow control during the treatment and low inflow restriction during production.