This paper discusses a new sand-face completion design suitable for stacked/multi-zone completions. Although the technique targets multi-zone applications, it is applicable to cased hole, a mix of cased and openhole, or openhole horizontal single-zone well scenarios. This design provides significant flexibility and optimizes tubular dimensions used to reduce the mechanical skin typically induced by completion components. The system is suitable for multi-zone completions that incorporate traditional mechanical zonalselectivity mechanisms or integration of intelligent zonalselectivity completion equipment.
Given adequate planning, the well may also be converted at a later date to or from intelligent well configurations without disturbing the actual sand-face completion.
In deepwater fields with heavy oil, the flexibility of this design and its potential for reducing the negative effects of mechanical skin on life of field production provides a positive economical impact. To date, one completion has been performed using the new configuration. From the success of that completion, others have been planned.
While deepwater fields are generally more prolific, the moresensitive deepwater scenarios are generally more costly to develop, and maximizing flow potential is critical to their economic success. In the most extensive deepwater reservoirs, such as those in Brazil, stacked multi-zone sand-control completions have been applied in both injection and production wells. Many of these completions involved fracpack-type completions with a fixed inner string and slidingsleeve circulating devices to provide a means for zonal selectivity. In many cases, the best approach for production optimization has been a combination of a sand control and a stimulation technique. Several technologies, which included frac-and-pack, extension pack with conductivity enhancer, and high-rate water-pack (HRWP) gravel packing have been used. Often, special completion tools that would enable greater flexibility on short string selective production in multi-zone gravel-packed wells have also been used. But when reviewing options, a combination of sand control and stimulation techniques (frac pack, extension pack and high-rate water pack) have been capable of increasing productivity and preventing sand production.1 While these completions have been capable of delivering the operators' goals, the completions discussed in this paper can offer alternative options and other significant benefits for the completion2.
The large-bore multi-zone completion design discussed in this paper provides flexibility for both high-rate water packs and frac-pack completions in conjunction with lower openhole-type sand-face designs. Three configurations are supported:
Scenario 1: A 4-in. fixed inner string having multiple 3.313 -in. inside-diameter flow-control devices facilitating the required zonal selectivity for any number of zones. This configuration uses current existing equipment and traditional practices for inclusion of the inner string. The string is either fixed in place when running or used initially as the wash-pipe during the sand-control treatment, and then, is adapted to remain in place to function as the inner isolation string.
Scenario 2: This is a design whereby the sand face completions in each zone are installed without the inner string but with a mechanical fluid-loss-control device that protects each zone.