Drilling advances

	Vol. 229 No. 4
LES SKINNER, PE, CONTRIBUTING EDITOR, LSKINNER@SBCGLOBAL.NET

New technology

New stuff. Invention. Innovation-I just love it. It’s one of the things that helps keep this old dog learning new tricks, and what nifty new ideas we’re seeing recently.

By now, we’ve all read about the new cement that is self-sealing should a hydrocarbon begin leaking along a microannulus or crack. Apparently, the cement contains some magic component that causes the cement sheath to seal off the channel in response to the leak. It reminds me of swell-packer technology, but this material is imbedded in the cement sheath itself. It almost makes me want to go block squeeze a bunch of old wells I once operated in a salt dome field near Beaumont. We always had communication between zones, and block squeezes never seemed to completely seal the annulus.

I had the brilliant idea once of dumping a bunch of glass microspheres in a cement slurry. Half of them would be full of resin and the other half with hardener, the two components of epoxy cement. Should the cement sheath crack under a load, several of both spheres would be sheared, releasing their contents to combine and glue the crack shut with a material that was harder and tougher than the cement itself. This would restore cement-sheath-sealing capability and mechanical integrity, or so I thought.

A friend of mine asked me how much of each component would be in each microsphere. I did a quick calculation and found that it was one cubic itty-bitty volume. The amount needed to seal a 1-micron crack all the way around a 7-in casing string would be one cubic itty-bitty volume x 20. So, forty of the little glass beads would have to break in every 1-micron crack in the correct proportion, meaning that most of the solid material in the cement slurry would have to be the resin/hardner-filled beads-not very practical and certainly not economical.

Besides that, I could never figure out how to get the resin and the hardner inside those little glass spheres. I suppose there would have to be a whole bunch of folks with itty-bitty hypodermic syringes poking a hole in the wall of the bead, filling the sphere with the correct material and plugging the hole with an equally itty-bitty cork-again, not very practical. I like the new cement system a whole lot better.

Another new innovation is a centralizer that is laser cut from a single piece of stock to create a bowspring design with no welds. I have seen a whole string of centralizers come out of the hole while pulling a stuck casing string with most of them balled up like a red ant on one casing collar. The welds had broken going in the hole, causing the pipe to stick in the first place. Milling the remains of broken centralizers in the bottom of the hole is like drilling on a chain. The whole mess spins and turns like a top, and many magnet runs are required to get the junk out of the hole.

The absence of welds means the centralizer is bound to be tougher and more damage resistant. Also, since it has no hinge, it can’t lose a pin and come off the pipe. Again, a welcomed change. I don’t know what these things cost, but if they save the cost of just one cleanout trip to remove broken welded centralizers from a hole, they have got to be worth it.

The solid expandable guys tell me that they are working on being able to successfully expand standard tubular goods, where in the past only special alloys were soft enough to be cold-worked in the expansion process. This meant that solid tubular expandables involved the higher costs of both materials and expansion. If they can pull this off, we can just call up our local ferrateria (pipe dealer) and order out as much API casing as we need, run it in the hole and expand it with no fear of splitting the pipe (within limits, of course).

I can’t even understand all the new advancements in PDC bit technology. One supplier has tried imbedding a row of backup cutters behind and just below the primary cutters. As the primaries dull, the backups are exposed and they begin to take part of the load, resulting in longer run times, better gauge protection and savings in rig time by avoiding unnecessary bit trips.

Here’s another new innovation. A university recently announced that it has perfected fuels derived from carbon dioxide. That’s right, boys and girls; if they are successful, we will soon be burning CO₂ (well, not directly, but CO₂ is the feedstock). USC’s Loker Hydrocarbon Research Institute has developed the chemistry to transform CO₂ into methanol and dimethyl ether, two “clean” alternatives to common transportation fuels. Now, they plan to go commercial with the process.

This simply must be nominated for the recycling project of the year award. The question I have is: What do you get when you burn this stuff the second time? C₂O₄?

Another possible crossover technology comes from biomedical research on the use of Inherently Conducting Polymers (ICPs) in bionics. There are several families of ICPs that are currently used in a variety of applications, primarily in nano-scale separation technology. ICPs are being considered, because of their benign nature, to replace current bionic devices such as cochlear implants, stimulators for spinal cord damage and hand control restoration devices.

What makes ICPs so interesting is that the properties of the polymer can be modified by sending a very small current (1 V or less) through the polymer. The polymer modifies its length, density, bulk, size and even color. When the current is removed, the polymer returns to its original shape. In the bionics field, this has amazing possibilities for artificial muscles and tendons.

Imagine what we could do with that technology in the oilpatch. Think about an ICP liner inside a tubing string in a producing well. If the well loads up with water, just send a slight current down the tubing string and cause the polymer to increase in volume (wall thickness), which would reduce the diameter of the conduit and the cross-sectional area for flow. This would increase fluid velocities to help the well unload. Then by removing the current, the conduit would return to its original diameter, allowing the well to flow at previous rates. Adjustable-ID production tubing!

Keep thinking, and stay safe out there.