In the days of old, people believed mischievous spirits were up to no good when bad things occurred. Over time, with the assistance of math, science, and a sizeable dose of creativity, those beliefs have gradually changed. Columbus put to bed the one-time popular belief that the earth was flat, just like Neil Armstrong’s little stroll confirmed that the moon was not made of green cheese.
Building upon the foundations these early collaborative efforts set and dictated by the need to think “outside the box,” it was made possible for humans to plumb the ocean floors of the ultra-deep waters offshore to facilitate the recovery of hydrocarbons from deeply buried reservoirs. Intricate highways of pipelines and production modules lie miles below the surface to safely transport its “passengers” to shore. And while the technical challenges in accomplishing such feats are many, operators have found that technology can help turn these challenges into successes.
Getting down to the basics
The roots of many offshore technical challenges can be traced back to two conditions: pressure and water depth. The greater distances from shore that exploration has opened up to production possibilities also play a role.
According to Brian Skeels, emerging technologies director for FMC Technologies, the “distance away from any delivery plane, vertically or horizontally and vertically” is growing more important.
“It is an interesting problem in that oil companies are going to deeper reservoirs, which are higher pressures, but by the time they get [the reservoir fluids] to the seafloor, the fluids don’t have enough energy to go the remaining distance on their own to the delivery point. So it is a weird paradigm.
“It doesn’t matter how much pressure you’ve got on the inside. If it has to go a long distance, the pressure might not be anywhere near enough to get fluids flowing at a decent rate,” he said. “So that’s why you might need pumps or compressors or separators that change the density of the fluid to make it easier so that the pressure drop isn’t as great to get from Point A to Point B.”
Enter the genies
Skeels believes that overcoming distance and low flow pressures is “probably the biggest challenge” facing offshore operators. But he also noted that extreme water depths present an equally challenging obstacle.
“Some of the technologies that attempt to make it easier for fluids to flow – pumping, compression, or separation – and the components associated with these technologies, like pressure vessels or tanks, have seals that work really great from the inside out but not from the outside in,” he said. “As we get into these very deep waters, the technologies that would help add energy to the flowstream could be thwarted by what’s going on by the extreme water depth.
“I like to differentiate between the two by calling one the red genie and the other the blue genie,” he said. “The red genie is in the bottle and is trying to get out and cause havoc, while the blue genie is the ocean trying to get into the bottle and cause an equal amount of havoc. The trick is in knowing how to keep them at bay in the process.”
A few of the solutions necessary to keep these two competing forces in check have been found through the reimagining of current technologies for use in smaller and harsher environments.
“For example, we’ve been looking at separator technologies that do not need giant separator tanks,” said Skeels. “These technologies use much smaller pipes, and the inside of the pipe can be designed in such a way that the oil and gas can be separated out in a much smaller environment than what is traditionally done. This technology was initially done to reduce the footprint size on platforms.
“FMC Technologies saw this as an opportunity to take this similar technology and marinize it, or adapt it for use underwater,” said Skeels. “Plus, its smaller size means it is more resistant to the blue genie trying to crush it.”
And the deeper one goes, the “more critical the change” is in engineering differences between platform and subsea production equipment.
“That’s what I mean by marinization and subsea. It’s trying to understand that there are two environments fighting each other,” he said. “Sometimes the way you would do things normally on land is different than what you would do in a pressurized environment. It’s a different environment, so the equipment needs to be redesigned to adapt to that environment.”
New perspectives, collaborative effort are key
In adapting to the subsea, accessibility to perform maintenance and repair is a more complex design consideration. Subsea components are more robust and require servicing in ways that are different from those components found on a platform. The use of ROVs and manipulators for the oil industry has helped ease the process of routine maintenance and repair procedures on components found in ultra-deep water.
According to Skeels, working with Schilling Robotics helps bring a different perspective to the drawing board. “It’s one thing to come up with these neat ideas for new components that’ll go on the seafloor,” he said. “It’s quite another to consider how to install it, how to maintain it, and how, in these great depths and long distances, to be able to do that. An understanding of the ROV side of things is a big help. It gives FMC Technologies another perspective.”
He added that he sees the need for “more and more collaborative efforts” to tackle future challenges, specifically HP/HT challenges that ultra-deep water will present.
“That’s one big area that everybody is working. There are some things that we have to understand fundamentally in materials, like seals. Materials behave differently at different temperatures.
“Also, some of this oil and gas is coming out of various tight formations, almost as tight as what you see for shales. So there are a lot of interesting problems with getting this new generation of hydrocarbons out of the ground – its corrosiveness and its makeup,” he said. “Because things are becoming so technically complex at those kinds of depths, it really relies on a collaborative effort as there are fewer simple answers to the problems down there.”