April 2014
Technology from Europe

Is wellhead design set for a revolution?

Ben van Bilderbeek believes the friction-grip technology developed by his UK-based company, Plexus Ocean Systems, is a major step forward in wellhead design, which can reduce the potential for blowouts, such as that which sparked the Macondo well disaster in 2010.
Fig. 1. POS-GRIP in open (A) and closed (B) positions.


World Oil: Where did the idea for your POS-GRIP technology come from?

Ben van Bilderbeek: I tripped over a very simple concept of engaging two pieces of tubing by clamping them together. It was based on a system in use for a long time called Ringfeder that is used to attach gears or aircraft and ship propellers to a shaft by putting a flange around the overlap and tightening it with bolts to create a friction grip. I turned that around and realized we could make a wellhead out of that concept.

So we used this existing principle, applied it to oil and gas field applications, and obtained a robust patent. Now we are the North Sea market leader in the surface exploration wellhead market. I believe we have the technology of necessity for HPHT wells for all applications.

WO: Where is it used at the moment in subsea environments?

van Bilderbeek: We chose to introduce the technology in a small sector of the market—jackup exploration drilling—because the technology is only used temporarily. The wellhead leaves the location at the end of the drilling program, so it lends itself to renting. If you are a company without very deep pockets, like us, then renting is a very efficient way of doing things. Otherwise, you need to become a manufacturer and make the equipment to sell, which means you have to invest in machine tools and everything else.

WO: So, how can you go about expanding your market?

van Bilderbeek: To operate in the production wellhead market, where the technology stays in position for the whole life of the well, rather than temporarily as in the exploration market, we would need manufacturing capability. So, we need to find a way to change the personality of our company. We think that is best done with a partner who already has the necessary infrastructure, rather than investing to become a manufacturer ourselves.

There are also the add-on components, such as valves and Christmas trees, so you need to be in that business to be able to sell the package. Just selling the wellhead isn’t the best way of marketing a wellhead system. We either need to find a partner to do this with and license the technology, or to make a strategic acquisition through which we grow the technology. We are considering both of these options at the moment.

WO: Has the business environment, in which Plexus operates, changed since the Macondo incident?

van Bilderbeek: Following the Macondo incident, senior managers at some oil companies decided they wanted to ensure that casing hangers would be locked down. They spoke to Plexus, because they were using our wellheads on the surface and wanted to see if they could use our friction-grip technology in the subsea environment.

WO: You’ve put together a joint industry project (JIP) to look into this. How did that come about?

van Bilderbeek: We have six partners in the HGSS JIP to develop a new subsea wellhead system, based on friction-grip technology. The companies are sponsoring it by bringing a broad range of opinions and experience to the table. For us, they also provide a potential client base.


Fig. 2. POS-GRIP 15 ksi HPHT exploration wellhead system.


WO: How is the JIP work progressing?

van Bilderbeek: We are going to execute and deliver this subsea wellhead system with all the bells and whistles. The internals of the system have already been qualified to 20,000-psi pressure rating under HT conditions. Test fixtures are under construction to prove the ability to deliver gripping power in the subsea environment. The intention is for one of our JIP partners to drill a trial well—who and where will depend on whether we decide to test it on a less challenging well in, for example, Africa, or whether we go the whole hog and drill with one of the major sponsors.

WO: You are up against well-established mandrel hanger type subsea wellhead technologies, on the market for 50 years and produced by larger rivals. Can POS-GRIP really make inroads into such a mature market?

van Bilderbeek: The subsea wellhead business has five main players. They have such a massive market grip that unless the industry actually decides that it is going to adopt our technology, our business just has to be grown organically, by supplying a few like-minded customers. What we will not do is to risk the company by trying to take them on directly, exposing ourselves to too high a debt profile.

Our competitors would say Plexus is very good at inventing problems in order to sell solutions. Only time will tell if they are right. I believe engineers should take the equivalent of a Hippocratic Oath, and fight to get better ideas into the market place. UK inventor James Dyson did that, with his vacuum cleaner, with phenomenal success. We are in a different market; but, in the same way, I feel it is very important for us to stick to our guns, to protect the technology and to make sure it remains available.

WO: How can you achieve this in practical terms?

van Bilderbeek: The best way to do this would be to exploit it through a ring-fenced organization supported by the industry. We have tabled the idea of setting up a new company, which we would participate in, but which we don’t need to control, because we could realize the value of our technology through a licensing agreement. This company could raise money from investors and make a strategic acquisition that would form the platform through which we can roll out the technology.


Fig. 3. POS-GRIP HGSS subsea wellhead.


WO: What is the next application for the friction-grip technology?

van Bilderbeek: If POS-GRIP technology is the best solution for HPHT applications, this axiom also holds true for all pressure ranges. The so-called lower pressure wells can be very dangerous, as was the case on the Macondo location.

The Arctic is going to be fertile ground for this technology. People who propose to use technology developed over the past 100 years in the Arctic will be inviting difficulties, because the range of temperature is so great that unless you have a technology that is able to cope with conditions from -40°F to 500°F, you will be in trouble. The fact that annular seals are eliminated and stresses are managed within elastic limits makes our technology reliable and reusable, and this is going to be key in the Arctic, where drilling is subject to the effects of temperature extremes, ice and rough sea conditions.

WO: Plexus has also been developing a product based on friction-grip technology for HPHT mudline well tieback. What progress have you made there?

van Bilderbeek: You can spend $500 million on drilling an HPHT exploration well, but you will have to drill a new hole for production, unless you can tie back the initial well. That takes both time and money. In low-pressure wells, you can tie back to mudline hanger profiles using resilient seal technologies, and perhaps metal interface seals, which cannot match the integrity of premium casing couplings. We, however, have the only system that can tie back HPHT wells with technology that delivers a standard at the tie-back point that can match the casing couplings in the system.

Maersk, the sponsors of the JIP through which our tie-back technology was developed, have told us they think they can save $100 million for certain applications using our tieback tool, without compromising the integrity of the casing design. wo-box_blue.gif



In the 1990s, Ben van Bilderbeek and his team at Plexus devised a method of clamping drill pipe in a wellhead, based on friction, by squeezing tubular components together through constriction from the outside. The technology works in the opposite direction to conventional solutions, where force is applied from the inside of the wellhead to push components outward, to engage seals and lock down the hangers.

van Bilderbeek says that this POS-GRIP technology is safer, less complicated and more reliable than the established alternatives—and that these factors could make it cheaper to use in the long run.

The technology has already gained traction for surface equipment and in the jack-up rig market in the North Sea, as well as among various operators drilling in Africa, the Middle East, Asia and Australia. Now, the company hopes its suitability for the HPHT environments will help it make inroads into markets dominated by its bigger rivals.

To that end, Plexus established a joint industry project, known as the HGSS JIP, in 2011, which now includes ENI, Maersk, Shell, Total, Tullow and Wintershall, to help develop a new strand of subsea wellhead technology to meet the industry needs.

To tackle the axial and bending forces generated in HPHT wells, drillers widely use systems with hangers landed on shoulders in the wellhead bore and locked down with expanding lock-rings, that are activated by seals inserted across the casing annulus. This, Plexus contends, means that such wellhead systems are unable to create sufficient force at the hanger-to-housing interface to ensure that the assembly remains rigid under all operating conditions.

Plexus’ friction-grip method of wellhead engineering exploits the elastic properties of material to deform the wellhead bore against the body of a casing or tubing hanger, instantly locking the assembly together, with a clamping force great enough to make the aligned components effectively ‘cold welded’ together—a process, which can also easily be reversed. The metal-to-metal interface seals set over an extended surface area by the technology enable it to resist the demands of HPHT applications, even in the most corrosive environments, according to Plexus.

This friction-grip approach removes the need to lift the BOP to land casing in the wellhead. The company says this “through the BOP” procedure, combined with the ability to provide clamping force from interface flanges, makes the technology safer than the conventional alternatives.

In subsea applications, the friction-grip method enables a new approach to subsea annulus management, by providing a simple yet effective solution that allows continuous monitoring, bleed-off and remedial access to selected annuli in subsea wellheads, without requiring penetrations through the wellhead body.  wo-box_blue.gif



BERNARD HERMAN VAN BILDERBEEK is founder and CEO of Plexus Ocean Systems Ltd. Mr. van Bilderbeek has over 35 years of experience in the industry, both in engineering and management roles. He has held senior positions with Vetco and Dril-Quip. In 1986, he founded Plexus and went on to merge the wellhead division of his company with Ingram Cactus, where he became president, Eastern Hemisphere. In 1996, van Bilderbeek regained the Plexus Ocean Systems name through which POS-GRIP technology was invented, and then developed and commercialized for the oil services wellhead equipment market. Mr. Bilderbeek has a mechanical engineering degree from Southern Methodist University in Dallas, Texas.
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