True Zonal Isolation in Openhole Alternate Path Gravel Pack Completions By
Michael D Barry, SPE, Michael T. Hecker, SPE, ExxonMobil Development Company; Charles S. Yeh, SPE, Tracy J. Moffett, SPE, ExxonMobil Upstream Research Company
A
bstract
Openhole completions are often selected as the preferred completion technique to maximize reservoir flow potential and provide reliable, high capacity, low skin completions. With the advances of Alternate Path® Technology (APT), a full gravel pack can be realized under challenging well conditions to provide increased long-term reliability. One drawback to openhole gravel packs has always been the inability to isolate water or gas, whether it is during the initial completion or during the production lifecycle of the well. ExxonMobil embarked on a multiyear initiative to develop, qualify, and successfully deploy Shunt Zonal Isolation (SZI) packer technology that, when combined with Internal Shunt Alternate Path Technology (ISAPT) screens, can provide true zonal isolation in an openhole gravel pack completion.
The new openhole technology enables greater extended drilling to capture additional pay, selective completions to isolate zones, and production flow control inside the screen basepipe similar to cased hole
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conditions. True zonal isolation in openhole gravel pack completions facilitates more flexible well planning and operational execution while maintaining reliable sand control. This paper will explore the range of application opportunities this new technology presents.
the openhole section of the wellbore. Using an eccentric 2x2 shunt system, APT utilized with the NAFPac® gravel packing process has proven to be extremely reliable in completely packing the openhole annulus while delivering reliable, high rate, openhole completions (Hecker, 2004).
Background
Although routinely deployed, the current eccentric 2x2 Alternate Path screens have both technical and operational limitations. These include: Maximum shunt system working pressure of 3,000 psi which limits the packable length to ~3,200 ft pumping using xanthan based carrier fluid Risk of shunt tube plugging with two independent tubes extending the length of the completion Complexity of rigsite connection make-up as oriented connections and cross-coupling jumper tubes are required Deployment exposure dictates that an outer shroud must be incorporated in openhole applications to protect the shunt tubes while running in the hole Challenges associated with designing an isolation packer
As operators continue to develop prospects in remote and / or deepwater environments, delivery of high capacity, long life wells becomes essential for economic success. High angle, openhole completions are often selected to maximize production and reserve capture. Standalone screen applications may often times be the least expensive and simplest form of sand control, but the formation characteristics may dictate that a gravel pack is necessary. If poorly sorted unconsolidated formations are encountered, gravel packing is often deemed necessary. Circulating water packs, or alpha / beta gravel packs, have been used worldwide, but may be challenged to achieve a complete gravel pack in certain applications. In order to achieve a complete gravel pack in such environments, APT has often been employed to fully pack
- November 2012
