Expandable screen offers new option for sand control

The first open hole expandable sand screen (ESS) has been field tested in a Shell Expro Ltd. well in the southern North Sea (Fig. 1 [96,757 bytes]). Petroline Wellsystems Ltd., Aberdeen. manufactured the ESS.

The ESS is an extension of the expandable casing technology (OGJ June 6, 1996, p. 31) pioneered by Shell and licensed by several service companies.

Petroline is developing the ESS for open hole, cased hole, and remedial applications. Petroline describes the ESS as consisting of a sand-exclusion screen that is capable of considerable expansion when a cone-shaped mandrel is driven through it. This allows the screen to be run in a preformed condition into the well, then expanded in the well bore to press directly against the formation.

Screen features

The screens feature expandable connections that allow any length of screen to be run with expansion over its entire length. Because it is expandable, the ESS also has remedial capability with significant potential cost savings for well workovers, according to Petroline.

Besides this field test, Petroline has completed comprehensive laboratory tests with the integral filtration medium, as well as mechanical testing of all components.

Calum Whitelaw, sand control product manager at Petroline, compares the ESS to a sandwich comprised of three layers (Fig. 2 [52,671 bytes]). The inner layer is the base expandable slotted tube (EST) that is slotted using an exclusive Petroline manufacturing process.

Overlapping leaves of a specially developed filtration medium are wrapped around this inner layer, and then a micro-EST is wrapped around the screen medium. This last layer protects the ESS against damage during installation.

Advantages

According to Petroline, some advantages (Fig. 3 [62,857 bytes]) of the ESS over existing systems are as follows:

Gravel packs are good at controlling sand but they can reduce production and are often risky and expensive to install.
Traditional nongravel packed screens are easy and relatively cheap to install but are prone to plugging and failure.
The ESS expands against the borehole providing support and eliminates the annulus and reduces sand movement, fines migration, and associated plugging. Because the annulus is removed, potential sand impingement and erosion risks are minimized, the filtration surface area is maximized, and future reservoir treatment and control becomes possible.
The ESS can be installed as quickly and as easily as traditional screens.
The overall well design can be slimmed down, thus yielding potentially savings on drilling costs.