In today’s competitive market place, operating companies are continually searching to find new and improved means of reducing costs and working smarter. Such a commitment creates challenges and requires companies to rethink best practices at almost every stage of the process. A key question in the drive for enhanced production is how best to control and manage water and sand. The recent introduction of a number of new technologies in this field has significantly improved performance with associated cost savings.

One important development has been the combined use of swellable elastomer packers and inflow control devices (ICDs), which can provide an effective regulator for sand and water.

As an example, Tendeka recently successfully deployed the world’s first slimhole ICD completion in a sandstone reservoir in the Gulf of Mexico (GoM).

Due to a severely depleted reservoir with difficult drilling conditions, the well was planned as a re-entry out of a 5-in. liner with a 4 1/ 8 -in. openhole, which negated the use of conventional technologies. Offset wells with sand-control equipment installed had experienced very high completion skin and used a variety of high-rate water packs, frac-packs, and expandable screens.

The company’s solution was to provide inflow control screens and swellable packers, which were installed in a 4/ 8 -in. openhole section of the well. Coarse metal mesh sand screens were used to minimize sand and mud plugging during well flowback. The swellable packers with a slip-on sleeve design were simple to deploy and quick to install. The new FloRight 2 3/ 8 -in. ultra-slimhole ICD screen system was used across the 558-ft (170-m) zone at a depth in excess of 13,123 ft (4,000 m).

The ICD technology used for sand control in the GoM was based on a recent successful 3 7/ 8 -in. openhole re-entry completion deployed by Tendeka in the Middle East to manage water in a producing openhole multilateral horizontal oil well. That project was another world first in that it allowed the deployment of passive ICDs to manage inflow from two lateral wells connected to the motherbore

The carbonate well reached 50% water cut. Limited success was achieved with plugging it back to minimize water production, so the company carried out a workover and installed the ICDs to passively control inflow from the laterals, uniformly produce from the motherbore, and reduce the potential for cross flow between the laterals.

Tendeka installed 14 FloMatik passive ICDs and six swellable packers into the motherbore to compartmentalize the reservoir. Numerous wellbore hydraulic simulation runs were undertaken to match flow and pressure profiles.

The ICDs created proportionate inflow along the well and passively controlled influx from the laterals with no cross-flow or packer leaks. A rate of 4,100 b/d of oil with 0% water cut was achieved, compared to 1,500 b/d before the workover.

The ultra-slim ICD completion in a trilateral well was implemented to control inflow from two laterals. (Image courtesy of Tendeka)

A swellable solution

In maturing reservoirs, water production management becomes an increas- ingly important issue. Production wells experience co-production of oil and water because of aquifer encroachment and/or water injection. As a solution, swellable packers can provide an effective seal against the formation, which can maximize the effectiveness of the water shut-off technique.

The basic principle of swellable elastomers is natural and very simple. Adding water or oil to the appropriate rubber-based compound causes it to swell as it absorbs the liquid. There are no moving parts to fail, and as long as the specific application is engineered and deployed correctly, very little actually can go wrong.

However, the inherent simplicity of the solution should not overshadow the complexity of the compounds and packer designs required to create a swellable packer solution for a well.

Swellable packers combine the advantages of both cement and mechanical packers without the inherent complications associated with these traditional technologies. The packers are thin sections of swellable rubber that are vulcanized directly on to tubing, swelling when they come into contact with the appropriate fluid.

Like cement, swellable packers take up any irregularities in the borehole, and like conventional packers, they create a pressure-holding seal within the well bore. However, unlike these traditional methods of zonal isolation, swellable packers always have something in reserve in case of a washout in the future, or if water breakthrough occurs. In such cases, the packer swells further and adapts to the new structure until a seal is re-established.

As an example, a major North Sea operator was planning to use through-tubing rotary drilling to sidetrack a 20-year-old well in the UK Continental Shelf, but traditional cementing was not practical for zonal isolation. The company decided swellable elastomer packers could provide the necessary answer.

Prior to sidetracking and the installation of the swellable packer solution, the well was producing 70% water cut through the main bore. The operator recognized that water breakthrough was likely to occur again, so the packer solution had to be designed to cope with both current and anticipated conditions.

Eight packers were run at depths of 13,500 ft to 15,300 ft (4,115 m to 4,664 m), primarily in the horizontal section of the well. Each had 16 swellable elastomer elements. This multielement configuration delivered a greater pressure holding ability and faster setting times without compromising the ability to run in hole with minimal risk. It also retained joint flexibility, making it easier to deploy many packers in long-reach horizontal sections. At key points between the packers, the operator introduced pre-perforated pipe, leaving blank pipe where water-producing zones were suspected.

Should the well begin to water out in the future, the design configuration of blank pipe, packers, and pre-perforated pipe allow a through-tubing swellable packer to be applied. The small running diameter of the packer allows it to be deployed inside tubing. When the swellable elements are exposed to water, they begin to swell, shutting off the water-producing zone.

The well was completed on time and on budget, delivering savings of more than US $10.7 million over a conventional sidetrack. When production began, the well flowed at a higher rate than expected with negligible water being produced.

Both swellable packers and ICDs currently are providing significant benefits and greater diversity than ever before in sand and water control. They are credible and proven additions to the reservoir optimization mainstream and offer new options for cost-effective completion designs.

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