Abstract
As easy oil in many fields is dwindling, there is increasing stress worldwide on innovative enhanced oil recovery (EOR) techniques. One forward-looking EOR approach is the workover method. It tries to convert currently weak horizontal wells to maximum reservoir contact (MRC) wells, or abandoned vertical wells to horizontal ones or power water injectors. Where conventional techniques fail, swelling elastomer seals and packers provide effective water shutoff and zonal isolation in even very complex environments, resulting in significant savings in rig time and development cost. One major issue of interest is the service life of elastomer seals and packers. It can be attempted to predict the probable working life based on the theory of accelerated testing. However, this forecast will not be very dependable for swelling elastomers as the material performance is substantially different from other rubber-type polymers. A full-scale test rig (one of its kind in the world) was therefore designed and fabricated at Sultan Qaboos University (SQU), in collaboration with a regional petroleum development company, for long-term service life assessment of actual full-size water-swelling and oil-swelling packers.
Highlights
As easy oil in many fields is dwindling, there is increasing stress worldwide on innovative enhanced oil recovery (EOR) techniques [1–6]
The test setup was built around some important modules: thermal system with capability of maintaining elevated temperatures continuously over a 5-year period; recirculation system to keep salinity at the requisite level; arrangement to pressurize the packers after sealing has been achieved through elastomer swelling, and maintaining it for several years; and a complex system for temperature and pressure measurement on both upstream and downstream sections in all packers
The gap between elastomer and the 7-in outer-casing is larger for the 31⁄2-inch packer as compared to the 41⁄2-inch packer; elastomer would have to swell an extra half-inch for sealing to be completed in the 31⁄2-inch units
Summary
As easy oil in many fields is dwindling, there is increasing stress worldwide on innovative enhanced oil recovery (EOR) techniques [1–6]. A full-scale test rig (one of its kind in the world) was designed and fabricated at Sultan Qaboos University (SQU), in collaboration with a regional petroleum development company, for long-term service life assessment of actual full-size water-swelling and oil-swelling packers [13] These packers are of different elastomer materials, kept in crude oil and saline solutions at different temperatures, and exposed to high pressures. The test setup was built around some important modules: thermal system with capability of maintaining elevated temperatures continuously over a 5-year period; recirculation system to keep salinity at the requisite level; arrangement to pressurize the packers after sealing has been achieved through elastomer swelling, and maintaining it for several years; and a complex system for temperature and pressure measurement on both upstream and downstream sections in all packers This unique long-term reliability assessment study is expected to provide helpful pointers to field engineers and application designers in appropriate selection of swell packers and in packer design enhancement
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