In the completion of many offshore wells, the installation of sand control screens is a necessary and vital step to ensure optimum production rates. Current procedures usually involve displacing the solids laden drilling fluid from the well with a clear or weighted completion brines in order to minimize any solids that could potentially plug the filtration media of the screens. Other methods entail special sizing of the drilling fluid solids such that they will pass through the screens. This paper describes a new method to protect against solids plugging while installing sand screens in muds containing solids of any size distribution.
The protection takes the form of a film which is wrapped or coated on the outside of the woven mesh filtration medium of the screen. The film is protected from mechanical deterioration by the outside shroud of the screen itself. During the installation of the screen, the film prohibits invasion of solids into the filtration area by providing a physical barrier. Once the screens are in place, the film is removed through decomposition by the well bore fluids. The decomposition step is initiated by a material in the film which has a minimum solubility threshold near the temperature of the fluids at the bottom of the hole.
The treatment is engineered for wells requiring sand control up to about 200° F (93° C) using either water-or oil-based muds. The treatment also offers a method to maintain the maximum filtration efficiency by protecting from solids invasion during installation.