A multipath screen system provides multiple benefits for an Egyptian deepwater sand control completion in the prolific deep offshore gas play of the Nile Delta.

Egypt's Simian/Sienna deepwater development posed a dual completion challenge for its developers: well life completions for high-rate gas producers and openhole completions in the face of highly reactive shales. Addressing the risks associated with high-rate production from an unconsolidated formation and the costs of deepwater intervention called for an innovative completion solution. Baker Oil Tools responded with its newly developed Direct Pak multipath gravel pack system.
A challenging field
The Simian/Sienna development is a high-rate gas field located in 1,800 ft (549 m) to 3,000 ft (915 m) of water in the West Delta Deep Marine Concession (WDDM) of the Nile Delta region off the coast of Egypt (Figure 1.) The development is operated by Rashpetco on behalf of the Egyptian General Petroleum Corp. (EGPC), British Gas and Edison Gas. The project consisted of eight subsea wells, each with expected gas production rates in excess of 100 MMcf/d. The wells were drilled and cased with 95/8-in. casing to the production zone and an 81/2-in. openhole gravel pack completion. These operations were all performed with a semisubmersible rig.
The completion scheme called for drilling through the producing zone and installing sand control completions to a depth of 6,000 ft to 6,600 ft (1,830 m to 2,013 m) true vertical depth subsea (TVDSS). Various uphole conditions required the final casing string to be set above a 30 ft to 45 ft (9.2 m to 13.7 m) layer of extremely reactive shale. This was in addition to the layered reactive shale within the producing interval.
High-rate gas production from an unconsolidated formation increases the risk of completion failure due to sand production which, in deepwater, increases the likelihood of expensive well intervention. Openhole gravel packing was selected as the completion method for the project based on durability and longevity in high-rate gas completions. Successful sand-free production through gravel packing in the nearby Scarab/Saffron development further influenced the completion type selection.
One of the most challenging obstacles for the openhole gravel packs was the potential for the exposed reactive shales to destabilize and swell. If the shale becomes unstable, the gravel pack assembly may not be able to reach the target well depth. Additionally, destabilized shales can lead to screen plugging and/or an incomplete gravel pack, jeopardizing the well life completion. Isolating the shale section with a behind-casing liner can solve the problem. However, it usually requires a reduction in screen size, which may impede production.
A multifaceted solution
To address the risk of unstable shales causing an incomplete pack and to retain an optimum screen size, the decision was made to use the Direct Pak system. The system addressed the developers' concerns in three ways. First, it provided an additional slurry pathway should the primary path of the screen/wellbore annulus for the gravel pack slurry transport become blocked. Second, it provided additional sand control from a premium Excluder2000 screen. Finally, it minimized the reactivity of the shale section during gravel packing by using Baker's SurFRAQ non-ionic visco-elastic surfactant as the viscosified gravel carrying agent during gravel packing.
The Direct Pak system consists of three main components: the tube system, the slurry transition ports and the cross coupling connector system. The tube system (Figure 2) is composed of four crescent-shaped tubes spirally configured around the exterior of the screen and welded to the outside of a support shroud. The crescent shape minimizes the screen system's outside diameter by conforming to a more rounded shape. Spirally attaching the tubes creates 360° of exit ports that balances distribution of the slurry as it exits the tubes. Wrapping the tubes around the screen provides centralization in an open hole, which creates proper screen standoff for complete gravel pack sand coverage of the screen. Additionally, each tube is completely independent of the others, which enables slurry to be transported down the other three tubes should an adverse event occur in one of the tubes during slurry transport.
Gravel pack slurry exits the tubes by means of slurry transition ports located every 5 ft (1.6 m) on a single tube and vented to direct slurry flow parallel to the screen. This configuration eliminates acute impingement of gravel on the well bore or the screen and minimizes the slurry's erosional effects. The port area is greater than the area of the tube itself, so slurry velocities are not increased going from the tube to the screen/wellbore annulus, and port erosion is minimized.
A two-part, clamshell-type device called a Cross Coupling Connector hydraulically connects the four slurry transport tubes at each screen connection in a timely manner. The connector aligns the tubes for proper slurry distribution and enables standard threads to be used on the screen joints. The design of the Direct Pak system makes timed connections unnecessary.
The SurFRAQ non-ionic visco-elastic surfactant was selected as the viscosified gravel carrying agent during gravel packing the Simian/Sienna wells. SurFRAQ breaks on contact with hydrocarbons in the reservoir and is ideally suited to maximize return permeability in sandstone formations.
Completing the wells
Typically, the major completion execution steps for each Simian/Sienna subsea well were as follows (Figure 3):
• 81/2-in. hole drilled through the targeted formation with water based drill-in fluid (DIF);
• 81/2-in. hole under reamed to 103/4-in. using water-based DIF;
• Open hole circulated to solids-free viscosified system;
• Cased hole cleaned with casing scraper and brine circulation;
• Gravel pack assembly placed downhole and well gravel packed;
• Upper completion installed; and
• Well flow tested.
The gravel packs were pumped at a rate of 5 bbl/min to 6 bbl/min using SurFRAQ with 6.0 ppg size 12/20 gravel pack sand added. During the third completion installation, a collapsed hole that ultimately
resulted from a 36-hour delay in operations caused by inclement weather proved the necessity of planned precautions against possible shale reactivity.
Four wells and counting
Thus far, four wells have been successfully completed in the Simian/Sienna development using the Direct Pak system. The gravel pack sand volumes as compared to theoretical screen/wellbore annular volumes indicate that complete packs were achieved. Sustained sand-free production from the flow test of each completed well indicates that the method was effective.

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