Smart pig technology focuses on one-way pipe applications

This design for an autononous rover might change the way flowlines are pigged.

Building on the same core tech nology developed for its bore rat, IIC is designing a smart pig that could change the way sub sea flow lines are monitored and cleared. Tom McIntyre, the director of technology for IIC, said the firm is working on a pigging device that can move up and down a flowline, carry fiber optic cables, and per form a variety of other services without leaving the inside of the flowline.

IIC is not a pigging company and does not design most of the components that would perform the temperature measurements and other data collection and remediation work. What IIC does design and manufacture is the rover technology that would transport this equipment and install the fiber optics. IIC would also design the hardware and software to allow the rover to operate autonomously in the flowline. If successful, this would offer an economical alternative to current pigging technology.

Pigging flowlines

Current pigging technology is based on a single ended flowline, meaning the operator only has access to one end of the line. Such lines include subsea flowlines which come off a platform or rig and terminate at the wellhead. For pigging purposes, these systems have to be designed with two lines so the pig can run in a loop, returning down the second line. While this is a viable solution for shorter flow lines, those installed in the future will stretch for several miles. At these great lengths, the cost of dual flowlines becomes prohibitively expensive.

An existing alternative to dual flowlines is to install a subsea pig launcher. This system allows a pig to be introduced into the flowline at the subsea wellhead via a remotely operated vehicle. Still, such a system is expensive.

IIC's design would eliminate the pig launcher by introducing a rover that could be sent down the flowline and then would be able to drive itself back up to the rig. These rovers would be battery powered and would need to return to the surface to be recharged.

McIntyre said there are several limitations to the current design that may be overcome as the technology develops further. One problem is that the rovers IIC has on the drawing board are designed to adapt to the radii of curvature for an oil well. That means they are short enough and narrow enough to move around a well or sidetrack without getting stuck in the twists and turns. Flow lines have much sharper curves than wellbores and this current generation of rovers cannot navigate through these tight curves. To overcome this problem, there would need to be an access point to the flowline somewhere below the steep curves where the lines come off the rig.

Curvature radii

In future generations of tractor units, the curve radii limitation will be overcome with tractors short and narrow enough to meet the 4-D radius of curvature seen in these flowlines.

The second limitation is a matter of power, if the rover is to stay in the flowline for an extended period of time it will need a renewable power source that is small enough to accommodate the twists and turns of the flowline.

In the first generation these pigs will run on batteries and must be retrieved for maintenance. McIntyre said as battery technology advances the pig could have an apartment on the flowline where it plugs itself in for recharging and reporting what it has found in the pipe. In this scenario the rover would put in a request for maintenance. Once these limitations are overcome the pig could stay in the flowline for an extended period gathering and reporting data and performing maintenance on the flowline. McIntyre said he is not sure what type maintenance the pigging tool could perform, but the current objective is to design the tractor and battery pack. As the design advances, more specific applications will come into focus. Not sure what maintenance the pig will be able to do. The current goal is to develop a device that can make the run down the flowline and back up again under its own power.

If the pigging tool were able to collect and report real-time data from the flowline, it would be useful not only in maintaining the line itself, but keeping up with paraffin or hydrate development. Using this information and the proper software package, an operator could specify the exact amounts of chemicals needed to maintain flow in the lines. By regulating this treatment, there could be a substantial savings in the amount of chemicals used to treat the flow and avoid interruptions in flow.

Charting temperatures

While this technology may seem very "blue sky," distributed fiber technology already exists that can chart the temperature profile along the entire flowline. The problem is these fibers cannot be installed on existing pipelines. McIntyre said the rover could carry the fibers down hole and either leave them in place for a period of time or use a disposable fiber line for short term measurement. These lines are thinner than human hair and similar to those used to control wire-guided missiles. These fibers could take the needed measurements and then be circulated through the flowline. This delicate fiber would then break up and be produced through the flowline.

The fiber, which is a proven technology, could give the full-distributed temperature of the entire flowline. This profile would show anomalies where a leak or wax buildup might exist. "Almost anything you can imagine leaves a temperature signature behind," McIntyre said.

So this application would simply combine a well-known technology, and IIC's concept for a rover, which would serve as a delivery tool. This project is in the development stage while the first application has not yet been scheduled. Devel opment time is minimal - 9-12 months - and IIC has the technology in place and expects to attract a partner for this project over the summer.

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