Welltec – precision robotics in the well
Feature Articles, Aug  14  2009 (Digital Energy Journal)

- Oilfield service company Welltec is making good progress with its robotic tools which can go into a well and perform perforations, clean sand or scale, set barriers and open valves, said Jørgen Hallundbæk, founder and CEO of Welltec.

Welltec designs and manufactures robotic tools which can go into wells on a wireline (electric cable) and perform jobs like remove scale and sand, make perforations, set barriers to isolate specific areas of the well and do small clean up jobs, said Jørgen Hallundbæk, founder and CEO (speaking at the recent OilVoice Forum in London).

Applying Welltec’s precision robotics usually proves more cost-effective than other methods, such as using a well intervention rig (snubbing) or coiled tubing, or pumping high pressure chemicals down the well.

With Welltec’s tools you can also get the job done quickly, if you need to. “We can do really rapid response,” Jørgen Hallundbæk said. “If that sort of urgency is within hours it’s all completely feasible. In some contracts we have equipment standing by - we can be in the ground within a few hours - solve the problem and get out again,” he said.

StatoilHydro has virtually stopped doing interventions by snubbing, doing them instead using electric wireline with equipment like this, he said.

Welltec has about 500 tools in use and does about 200 operations a month around the world.

Welltec started off in 1994 with the Well Tractor, a tool which can go into the well pushing its wheels against the side of the well to convey logging and other tools. Wireline conveyance presents an alternative to lowering tools in hole by relying on gravity– and is more effective when the well is not vertical.

Since then the company has expanded to offer a range of different precision equipment, including the Well Stroker launched in 2003 with support from BP.

Costs

StatoilHydro did a study to compare the costs of increasing production from drilling new wells or getting more out of existing wells using equipment such as Welltec’s.

They found that the ratio of cost of increasing production from a new well compared to from an existing well was something like 1:6.

“The oil is 'practically free' compared to the cost of drilling new wells,” Jørgen Hallundbæk said.

“In the past the approach was that you had 40 well slots on a platform - and once production started deteriorating you would sidetrack to a new well and start producing from there,” he said.

“But they realised from using Welltec’s technologies it paid off 6 times better by using these technologies - and then they still have the drilling rig available on the platform,” he said.

“Very often, problems are actually caused by simple well issues,” he said.

HSE benefits

There are big environmental benefits to using Welltec’s equipment rather than equipment that requires a drilling rig in order to function. For example, there is much less equipment needed to be delivered to the wellsite (and equipment can sometimes be delivered by helicopter), which leaves a much smaller carbon footprint than alternative methods.

As mentioned, the Welltec equipment makes it easier to get more production out of your mature wells, so there is less need to drill new ones, something that has a huge impact on the environment.

You can also avoid pumping high pressure chemicals into the well for further environmental benefits.

There are also safety benefits – the equipment can normally be operated with less people than if you need a workover rig. As the equipment is remote controlled from surface, as little as two people can perform an operation miles away from the well. In Norway, the equipment has even been running in offshore wells and operated from shore.

“We can even operate tractors from the shore. We can remotely operate the wireline, drum and tractors downhole. Some of the jobs we are doing in Norway are remote control - via fibre optics,” he said.

The company decided it would make all of its tools 90 per cent recyclable from the beginning. “All the metals are scrapped and recycled again,” he said. “And we have an oiling system - a small can of oil - it’s brought back and recycled, which means that we leave no mark.”

Improved planning

Having the tools available also makes it possible to plan the well in a different way. Instead of putting a great deal of equipment down the well when it is built to be ready for future challenges, you can build the well simply and add more equipment as required using Welltec’s tools.

“A lot of wells have been designed to be intervention free for their whole lifespan, say 30 years, but we often see a few years down the road something went slightly wrong or didn’t behave and it needs some kind of intervention,” he said.

Welltec’s tools allow a different approach. You can start your reservoir with a low capital expenditure and then change your well as you realise your original assumptions were not exactly what you thought.

The tools also make it possible to plan well interventions in a different way. For example, if a well intervention is needed but you don’t know how difficult it will be, you can start using Welltec’s tools and then bring in heavier equipment once you are sure that it is required. This results in both lower cost and environmental benefits if the lightweight tools can perform the same job as huge and heavy equipment.

“If a snubbing operation is not necessary - why not start with something light and move to the heavier operation when you need it?” he asks.

“We can solve a lot of problems which were solved 10 years ago by snubbing,” he said. “Things which would have been impossible in the past are being done on wireline today.”

Oil companies are doing more and more well interventions, because it is becoming much cheaper to look for ways to increase production from the wells you have, rather than look for new areas to drill. Some mature fields have interventions done every 18 months. “It’s a massive amount of oil you can produce from these well interventions,” he said.

Pressure pumping

Welltec often finds itself competing against the $20bn oilfield pressure pumping industry where chemicals are pumped into the well at high pressure to do jobs like remove scale.

These tasks could often be better done using robotic tools, which can carefully mill the shale away with keyhole precision, and then polish the inside of the well so that shale won’t stick to it again.

There are examples of how the reservoir has been damaged from pressure pumping. “Often on depleted reservoirs, it’s not a good idea to pump fluids down the hole - you might mess up the reservoir and it won't produce afterwards,” Jørgen Hallundbæk said. “You then spend an awful lot of time stimulating the reservoir to try to get it back again.”

When working with liquids, a lot of money is spent just pumping liquid out of the well at the end. “It's a major fluid column we have to remove,” he said. “We have to bail it out or continuously well lift. It might take 2-3 weeks to get the column balanced again.”

“With our system - you can see as you're doing the operation that it actually works.”

Establishing full flow

The Welltec systems can also clean scale from equipment, such as downhole safety valves. The tools can have a power of up to 1.5 kW, as much as a home hairdryer – but this is enough to mill through scale.

The tools are often used for sand removal. “A lot of oil wells create sand dunes at the heel and then production sort of stops,” he said. “Today, operators are willing to let us engage in jobs where we do 50 runs of sand removal.” The reason is that despite the many runs, the sand can be removed quickly, safely and with a much lighter impact on the reservoir.

Recently, Welltec introduced a new system that is able to both mill out obstructions and also retrieve the cuttings generated during the milling process to surface.

Previously, this could not be done in the same run so with this new system cost can be reduced by more than 2/3 compared to coiled tubing or rig work-over operations.

When downhole obstructions are removed from the well, full flow can be established to increase production.

Forget ‘smart wells’

Instead of installing expensive ‘smart wells’ where a part of the well can be closed off once it starts producing water and open another part of the well, why not use Welltec’s equipment to block and perforate new areas of the well as needed?

With ‘smart wells’, a large amount of expensive equipment (also referred to as ‘jewellery’) is put in the well at the beginning, which might never be needed – or if it is needed, the valve might have seized shut by the time it is needed.

“Most intelligent well systems have manual override systems - we can go inside a smart completion and manipulate the valves inside if they fail,” he said. “But is it necessary to build them that fancy [in the first place]?”

“To put all that in the ground - you need a big well head or a narrow production tube.”

Instead, Jørgen Hallundbæk suggests that you “start your well design very simply, then as time passes by, you can repair your field, put in flow control valves in existing well bores, and they can be maintained and de-scaled.”

“What is the right balance between how many sensors, valves, how many permanent things?” he asks. “Can some reservoirs better be drained with more simple completion technology, allowing smaller wellheads and smaller equipment in the ground? It’s a different approach to slimhole drilling.”

Well Tractors can be used to inflate barriers downhole, which can control liquid flow within the well.

So, for example, you can gradually move the part of the reservoir you are producing, by blocking the flow from one perforation and creating a new perforation. For example, if the water level is steadily rising in the well and you want to make sure you are producing oil, not water.

“It’s a very simple, cost effective way of producing from several zones - you can produce from each zone [then move to the next],” he said.

For more information about Welltec and precision robotics, please visit www.welltec.com

Welltec, Well Tractor, Well Stroker, Well Key, Well Cleaner, Well Miller and Welltec Release Device are trademarks of Welltec A/S and may be registered in Denmark and/or in other countries. All products are protected by patents or patent pending.

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