Subsea technology questions Subsea technology questions

At 300 meters depth, we have it covered. But at depths up to 3000 meters, the physical conditions demand a radical re-think around techniques and technology.

The challenge: Installation and maintenance

Lowering a subsea production template to a depth of a few hundred meters, using cables is a relatively straightforward process. But as the depth increases, the dynamics change. There comes a point where the weight of the cable played out exceeds that of the template itself — and it keeps on increasing, placing enormous stresses on the surface vessel. Is there an alternative method of installing subsea equipment? Increased depths present additional challenges for the maintenance of pipelines and equipment. Would it be possible to employ autonomous remotely operated vehicles which remain on the seabed and are capable of operating without the need for an umbilical? These are just a few of the challenges we face. Any good ideas you might have on subsea installation and maintenance are welcome.

The challenge: Installation and maintenance

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We've pioneered robust solutions for separating produced oil and gas from water and sand on the seabed down to 300 meters. But greater depths require more resilient, compact and cost-effective solutions.

The challenge: Separation of oil/gas/water and sand!

We have successfully developed separation facilities which remove the need to take the produced mixture of oil, gas and water to the surface, and significantly increase recovery. It works well, but in deeper waters, the design of the structure simply would not work. There may be other methods of separation – for example involving centrifugal forces – but how could these be made to work reliably at depths up to 3000 meters? We face many challenges. Answers to these, or any other good ideas related to the separation of oil, gas, water and sand are welcome.

The challenge: Separation of oil/gas/water and sand!

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Water separated from the well-stream can be re-injected. But as the depth increases so do the physical challenges, as well as the costs. Is there an alternative to re-injection?

The challenge: Produced water disposal

The produced mixture from the wellstream can typically comprise of up to 90% water. In the course of extraction, this means dealing with significant quantities of water. On a platform, water can be treated so that it can be disposed of at sea, or alternatively produced water can be re-injected into the well. At greater depths the cost of bringing the produced water up to the platform with the wellstream increases and the costs involved in drilling a well for re-injection become prohibitive. Is there a better, more cost-effective way of handling water at these depths? Your answer to this, or any other good ideas you might have related to produced water disposal are welcome.

The challenge: Produced water disposal

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In our industry, knowledge is power. But placing monitoring and control systems further from command centers brings out a range of new challenges over reliability and accuracy.

The challenge: Remote monitoring and control

Temperatures. Flowrates through pipelines. Precise quantities of oil and gas in the wellstream. These variables, as well as many others, require constant, accurate monitoring. And yet, at the extremes of the subsea environment, conventional means of measurement may not always be the most durable. But what are the alternatives? The control systems we employ have typically been connected using copper cable. These are gradually being replaced by fibre optics as a more effective means of transmission. But there may be other solutions, and the question of how to power these systems over increasing distances remains. Do you have any answers to the above, or any other good ideas related to remote monitoring and control? Please let us know.

The challenge: Remote monitoring and control

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As tie-backs to infrastructure increase in length, how is it possible to maintain a consistent, reliable power supply to installations on the seabed?

The challenge: Long distance power transmission

Photo © Expro Connectors & Measurements

Over longer distances, the principal challenge is how to maintain a stable power supply to the remote production facilities, which in some cases can be more than 100 km from land. In addition, to install electrical equipment such as compressors, pumps and the necessary electrical controls and switchgear at even greater water depths is to place them in a particularly hostile environment. One solution has been simply to encase equipment in a pressure chamber. However, particular challenges remain – not least how to maintain the integrity of the chamber, and the electrical connections, especially where power cables penetrate the chamber walls. What are the solutions that will allow electrical equipment to keep on working at increased depths? Your answer to this, or any other good ideas you might have regarding long distance subsea power transmission are welcome.

The challenge: Long distance power transmission

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It may be possible to power smaller installations and control systems using localized sources. But what form could these power sources take?

The challenge: Local power generation and storage

To avoid the problems presented by the increasing length of power feeds, one solution would be to use power generated locally to run equipment on the sea bed. Known means of generating power could include water turbines, or windmills on the sea surface. But what are the alternatives? Also, what is the best way to store energy from these power sources? Are there batteries that could be used at increased depths? Or systems for storing energy using a flywheel? We are open to any ideas related to local power generation and subsea storage.

The challenge: Local power generation and storage

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Working at extremes of pressure and temperature, subjected to corrosive and abrasive forces, traditional materials rapidly reach the limits of performance. But what are the materials that can replace them?

The challenge: New materials

The environments we work in and the operating conditions we're forced to deal with place equipment and materials under extreme pressure. Sand content in the wellstream flowing through pipelines under pressure is highly abrasive. Sea water and the fluids extracted from subsea wells are inherently corrosive. Wax and hydrates can form and adhere to pipelines at low temperatures, causing blockages. In each of these scenarios, and others, the choice of materials we use could provide a more effective and durable solution. But which materials? All good ideas are welcome.

The challenge: New materials

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Thank you.

Subsea technology questions Sigrun Daireaux Business Developer idea@statoil.com innovate.statoil.com