The ResFlow Inflow Control Device (ICD) is designed to optimize production or injection in openhole completions by equalizing flow along the entire length of the well bore. Used in conjunction with sand management media, ICDs work two ways — for producing wells, they even out the inflow patterns of produced fluids, moderating localized high-rate flow in areas of high formation conductivity; for injectors, they improve sweep efficiency by uniformly distributing injection flow patterns along the completion.

In producing wells, evening out inflow patterns mitigates premature coning of water or gas. In wells that include sand management media, ICDs mitigate localized erosion that can damage and compromise the media. When ICDs are combined with LineSlot single wire-wrapped sand screens, a production management system is produced in which sand control and flow control are intelligently integrated in a simple, robust, and reliable solution.

In the ResFlow system, produced fluid enters through the sand screen apertures and is guided by axial rods to the upper end of each screen housing. There, it passes into the base pipe through several ceramic nozzles. The nozzles are field-adjustable by replacement prior to running the completion, so flow rates can be optimized on a well-by-well or zone-by-zone basis. A proprietary modeling program helps operators choose the optimum nozzle size for their well. The system is viscosity independent, enabling flow velocity to be factored in for maximum sweep efficiency and water cut reduction following breakthrough. There are no moving parts or control lines to deploy. The device is self-regulating, eliminating the need for downhole telemetry. Nozzle apertures are 10 times larger than screen openings, eliminating plugging potential.

The ResFlow ICD has a nozzle-based design that makes it viscosity-independent and provides enhanced sweep efficiency on the reservoir. ResFlow ICDs complement LineSlot Direct Wire Wrap screens to provide effective sand control downhole. (Image courtesy of Schlumberger)

The modeling program can be applied to producing wells or injectors. Through its use, operators can calculate the optimal nozzle size for each screen in the completion. This allows them to achieve uniform flow across the entire completion, thus optimizing sweep efficiency for injector wells and preventing two common problems affecting producing wells — coning and sanding. Zones of high conductivity are most likely to cone water or gas, causing premature breakthrough, but when flow rate is suppressed in those zones, overall production is optimized. Sanding occurs when production alters the local stress pattern that holds the sand grains in place. This condition is predictable, and in zones of high flow, damaging erosion of the screens can occur. By adjusting the flow rate with the correctly sized nozzles, this condition can be mitigated.

Large-scale application reported

From July 2008 through January 2009, the ResFlow ICD technology was applied in the world’s largest offshore oil field. Previously, the operator had experienced plugging of its sand screens and its ICD design, which depended on a long, viscosity-dependent helical tube to create the required pressure drop. The previous system was problematic because it was inefficient in slow-flowing reservoirs and sweep deficient, particularly after high-volume water breakthrough. In addition, it proved to be particularly susceptible to scale build-up or plugging.

In its first year of operation, the application of ResFlow technology in the field has represented savings of about US $130 million, calculated by reducing the need for 13 new wells. This was achieved because productivity increases averaging 67% were experienced by the first 32 wells equipped with the new system.