Case History: Overcoming the Challenges of Deepwater Gravel Packing by Using Viscoelastic Fluids in Wells with Concentric-Annulus Completions

Abstract

Abstract Viscoelastic Surfactant (VES) Fluid technology was applied in the gravel packing of 18 deviated open-hole wells, having concentric annular completions, in Deepwater offshore India, with excellent results. The formation is unconsolidated, friable and highly permeable with very little margin between pore pressures, wellbore breakout pressures and fracture pressures. A preperforated liner was placed in the under-reamed open-hole section to protect against wellbore instability, and the sand control screens were landed inside the liner forming a dual annuli or concentric annulus, which was then gravel packed. Conventional gravel packing strategy suggests manipulating pump rates to minimize downhole pressures. However, with VES fluids, surface and bottom-hole treating pressures are easily kept to a minimum until screenout. This paper summarizes the challenges encountered; lessons learned and highlights the key advantages of the viscoelastic fluid systems used in these applications. The superior proppant-carrying capabilities of the viscoelastic system was proven showing higher success rates in complete packing of the open-hole sections compared to wells gravel packed using HEC-viscosified fluids. This paper also includes the details of the laboratory development and optimization of the VES fluids for both formate and calcium chloride based gravel pack carrier fluids. This involved screening of possible viscoelastic surfactants by compatibility tests, VES fluid rheology tests, internal breaker tests for the specific well conditions and friction pressure tests. The VES fluids’ superior proppant carrying capabilities, friction reduction properties, cost effectiveness, and non-damaging effects were the key success factors in overcoming the gravel packing challenges. The lessons learned from this project can be utilized in similar deepwater or extended reach applications to assist in improving success rates in gravel packing long open-hole intervals.