<a href=Fishbones ” class=”fullwidth” src=”https://www.offshore-technology.com/wp-content/uploads/image-digitalinsightresearch/nri/Fishbones.jpg” />

Work on a new multilateral well stimulation technology started three years ago as a joint industry project between Fishbones – a Norwegian oil and gas technology company – and Statoil, Eni , Lundin , Innovation Norway , and The Research Council of Norway. Now, there are ten major oil companies supporting the project, including Shell , Total and BP.

The new system called Dreamliner multilateral well stimulation (MST ) is an open hole liner completion that essentially creates a network of routes in a reservoir that connects them to the well, increasing connectivity and productivity.

How it works

The Dreamliner system is installed as part of a liner sub that houses small, high strength titanium tubes called needles to jet out into the formation, which is positioned across the formation where the well needs stimulating. Each needle is 40ft-long, has a jet nozzle on the end and is driven by a turbine. During the jetting process, a small lateral is created, which connects up the existing fracture network.

Stimulation is performed on oil and gas wells to increase production by improving the flow of the hydrocarbon resource. Sometimes a well has low permeability, so stimulation by acid, petroleum or steam is required to make the rock more porous so to initiate production from a reservoir. Stimulation is also used when permeability and flow from an already existing well needs to be encouraged if it has become under-productive.

"Stimulation is performed on oil and gas wells to increase production by improving the flow of the hydrocarbon resource."

In a carbonate formation, a basic hydrochloric acid (HCl) fluid system is pumped, acid shoots out of the nozzles and the formation ahead of the tubes is dissolved. Differential pressure across the liner drives the needles further into the formation and they penetrate the rock until fully extended, creating channels through which the hydrocarbon source can flow.

The channels expand through the well laterally like the ribs of a fish skeleton. This means more contact points in the rock can be perforated to release oil or gas, without the contact points getting ‘out-of-hand’ or penetrating into gas or water zones. In the developers’ words, one straw is good, but many straws are better.

"We provide more access to the actual reservoir," says Fishbones North America Region Manager Kevin Rice. "Typically you drill one hole into a reservoir and that’s what’s used to drain. It has a certain amount of contact, like one big straw. We take that one great big straw and add off to the sides a lot of very small straws that can go out and touch the rest of the reservoir."

Superior to fracturing

Dreamliner is basically giving engineers an alternative to hydraulic fracturing, where rock is fractured by a pressurised liquid, making cracks in deep-rock formations through which natural gas, petroleum, and brine can flow through.

By using the Dreamliner MST, up to 200 lateral channels are created in the reservoir, each 40ft-long, which allows the operator to increase recovery rate and drain reservoir faster than hydraulic fracturing.

This method comes with challenges, because all targeted intervals have to be consistently stimulated. Also, the growth of hydraulic fractures in the vertical direction can be difficult to predict, so you risk entering gas or water bearing formations. Operations can be complex and costly.

Using several smaller channels limits any risk of going too far into the rock. The system also uses less resources; 95% less fluid consumption than normal fracturing. "We can eliminate or greatly reduce the need for chemicals," the researchers say, which would lessen the environmental impact of groundwater contamination and the disposal of recovered stimulation fluid considerably.

Direct environmental impacts from well stimulation include contamination to water supply, induced earthquakes, and impacts on air quality. Using less environmentally damaging chemicals reduces the risk of polluting the surrounding area.

A Dreamliner design network also minimises expensive equipment; the entire operation can be completed without the need to bring a frack truck or a fracking vessel to the drill site. The reduction in man-power and the simplicity of the system means that it is a safer alternative, with a decreased risk of injuries to personnel.

Also MST productivity does not decline over time, which is the case with fractured wells due to fracture closures. The system is much more efficient than drilling conventional laterals and can drain a well more rapidly.

"It takes a week to do one," Rice says. "We’re doing up to 300 in a period of hours."

The proof lies in case studies

"The reduction in man-power and the simplicity of the system means that it is a safer alternative."

Back in 2013, a Fishbones stimulation system was installed for the first time. The project took place in a coal field in South Sumatra to investigate its resource potential. A 800m-deep, vertical well was drilled with a 180m-wide open hole.

In 2014, the Fishbones’ MST was successfully deployed in the tight Austin Chalk formation in Texas and 30 days later the company reported that the well was producing better than ever before. Production was increased by over eight times and the productivity index increased by 30 times.

The liner-based stimulation technology was originally developed for carbonate reserves (sedimentary rocks). Experience in the field has shown that the Dreamliner MST has proven to be successful in both tight limestone formation and carbonate reservoirs.

For example, in July 2015, Fishbones Dreamliner MST was successfully installed in a new, horizontal well in a sandstone formation in the Norwegian Sea. The sand formation had low permeability, so the reserves were previously considered non-economical to develop to access the gas reservoir underneath. The Fishbones system could be the solution to this.

Fishbones has developed a unique and cost-effective technology to get more production out of challenging reservoirs, and with the support from big names it could soon become a global, fully operational service company. The first task was to achieve simplicity, accuracy and efficiency with the Dreamliner, so the hard part is done.