Swellable Packers Combine With Expandable Sand Screens To Deliver Better Than Expected Well Performance In Nigeria

SPDC (Shell Petroleum Development Company of Nigeria) has successfully combined expandable sand screen technology with Swellfix’s swellable elastomer packers to reduce costs and provide an effective and reliable completion in a gas well in the Gbaran/Ubie field in Nigeria’s Bayelsa State.

Over the past decade expandable sand screens (ESS), developed around Shell’s patented expandable pipe technology, have become commonplace in oil and gas wells around the world. The technology is now firmly established as a reliable solution for sand control, which delivers both production and cost benefits.

Figure 1: Swellfix E-Zip isolating a water producing zone, while allowing oil production from other zones.

Shell developed swellable packers now produced by Swellfix. They are a more recent development now being recognised as a dependable and economically beneficial completions technology.

SPDC has successfully combined the two technologies in Gbaran-11st, an onshore gas producer in Nigeria.

The Swellfix packers have been utilised above the sand screen sections to provide zonal isolation above the gas reservoir.

The basic principle of swellable elastomers is natural and very simple. By adding water or oil to the appropriate rubber based compound it will swell as it absorbs the liquid. There are no moving parts to fail, so as long as the specific application is correctly engineered and deployed, there is very little room for error.
However, the inherent simplicity of swellable materials masks the real skill required in a created swellable packer solution for a well.

There are essentially two main types of swellable elastomers used for down hole packers, oil or water swelling, the SPDC well completion used a combination of both types.

Water swelling elastomers work on the principle of osmosis, a process that encourages the movement of water particles across a semi-permeable membrane, where there is a salinity difference on either side of the membrane.

Oil swellable elastomers work on the principle of absorption and dissolution. The swelling rate and volume increases are directly related to the composition and characteristics of the oil.

Swellfix supplied three 10m multi-swell water and oil swellable E-ZIPs – the product name for the company’s zonal inflow profiler. Each Gbaran-11st E-ZIP features seven water swellable and six oil swellable elements.

The swellable packers are made of thin sections of swellable rubber that is vulcanised directly onto pipe – in this case seven inch 13Cr. The rubber swells to form a seal when it makes contact with the appropriate oil or water.

Figure 2: Swellfix expandable elastomer packers.

The completion

The well was drilled to a terminal depth of 3,853 metres. The sand face completions assembly was then ran to the bottom of the well without any significant issues. Once it was in place, the expandable sand screens were successfully expanded and the Swellfix packers were set.

The Gbaran-11st oil based packers were set using the oil based mud in which the completion was run. The final seal was achieved within 44 days. The condensate in the gas produced during normal operation of the well will keep both the oil and water elements of the E-ZIP packers swollen at their optimum levels for the life of the well.

The well was successfully tested to 50MMscf/d with no sand production, limited only by surface equipment and is currently closed-in awaiting the completion of production facility.

Commenting on the project, Swellfix’s Garron Lees said:

• “The Gbaran-11st project is a good example of how modern technologies can be combined to provide new types of down hole completion that wouldn’t have been thought about not that long ago.
• Expandable sand screens have had a dramatic impact on the industry over the past ten to fifteen years and they are now widely regarded as a preferred option to traditional gravel packers.
• Swellable elastomer based packers are now also establishing themselves as a solution of choice, in preference to mechanical packers, with more than 3,000 Swellfix products now deployed around the world”.
• To find out more about swellable elastomers please visit www.swellfix.com or contact Garron Lees on +44 1224 896 100.