Sand as a Problem

This blog celebrates sand and its wonders, its intersections with our lives and the processes of our planet, but, let's face it, sometimes sand can be at best a nuisance and at worst the cause of major problems. As the poet Robert Service is reported to have written, "It isn't the mountain ahead that wears you out - it's the grain of sand in your shoe." Sand gets everywhere and penetrates everything, and sand and mechanisms of any kind do not mix well - "sand in the gears." Sand and electronic devices represent a particularly lethal cocktail, as I found out to my frustration. At one point during our Western Desert trip, attempting to follow in the footsteps (and tire tracks) of Ralph Bagnold (the man who figured out how deserts work), we were struggling to reconcile the different scales of the original maps with the ones we had, and to convert locations to GPS way-points. I helpfully remembered that, like all mobile (cell) phones, mine had a calculator, and I extracted it from safekeeping in my backpack. The necessary calculations were made, and we were off - but I neglected to properly re-secure my phone, leaving it vulnerable to the Sahara and the two sandstorms we subsequently enjoyed. By the time, ten days later, we arrived at the relatively civilised environment of an oasis and I was ready to phone home, I discovered that the keys would only respond occasionally to even severe pounding, and that the process was accompanied by that faint crunching, gritty, sound. Penetration had clearly occurred (I believe this was also when granular materials found their way into my knee joints). And to think that I had, at one point, been contemplating bringing a notebook computer.

When I was back in the UK, I took the phone to the shop where I had bought it, and explained that it had ceased to work properly, muttering about "ever since I passed a building site on a windy day" - it was repaired under the warranty. But now I have made an interesting discovery. I was reading the Geographical Magazine, our equivalent of the National Geographic, published by the Royal Geographical Society (I was particularly enjoying this issue because they reviewed my book). In addition to the review, there were a number of articles of minor interest, but one caught my attention. Written by Bernard Sèbe, it described the "gear he took on his camel-dependent journeys across the Sahara." In addition to advice on choosing your camels, and whether to hire or buy them, he listed a "ruggedised computer" that "should resist sandstorms and maybe even a camel stampede. It's as heavy in your hands as it is on your chequebook, but you'll no longer worry about grains of sand destroying your machine." It turns out that, of course primarily targeted at the military market, there are extremely tough laptops and notebooks out there, and I looked up the recommended manufacturer on the internet. Below is a "Toughnote" ruggedised computer, that I have tastefully placed in the Saharan sand, next to some fossilised wood. I'm pleased to say that these are made in the UK by a British company; the website exhorts you to "get a quote" ...... They make ruggedised laptops, notebooks, hand-helds and peripherals; I was tempted to title this post "any computer port in a storm." Sorry......

And then, in an entirely different publication, I was yesterday treated to the image below, accompanied by the words

Feeling the heat? Are sand management problems impacting your bottom line?

Well, I thought, the book sales could be better, perhaps.... and then I realised that it was a different kind of sand problem. Let's, for a moment, put aside the issues about fossil fuel use, accept that, at least for today, oil and gas are quite useful for our way of life, and consider the truly remarkable technology and engineering that goes into extracting them. These critical resources do not occur in subsurface lakes, rivers, or caverns; they inhabit the microscopic holes in buried rock, very often the spaces between sand grains. Any rock that, like a sponge, is sufficiently porous to hold significant amounts of water or hydrocarbons is called a reservoir. The quality of a reservoir for any fluid, whether it's water, oil, or gas, depends on its porosity and permeability—how much fluid it can contain and how efficiently it will give it up. These characteristics depend on the nature of the sand grains, the spaces between them, and the connections between the spaces. But however porous and permeable a reservoir may be, it will never give up all its fluid; the same surface tension effects that help build sand castles hold water or oil onto and between the grains and keep more in the rock than can be extracted. If the reservoir is under natural pressure, then, once a hole is drilled into it, the fluid will flow to the surface of its own accord; otherwise it has to be pumped. The world’s largest accumulations of oil and gas are found in the spaces between sand grains, as are countless numbers of smaller fields. In Alaska, Saudi Arabia, Russia, and elsewhere, the reservoirs are made of sandstone. The reservoirs at the giant Prudhoe Bay field in Alaska are Permian and Triassic sandstones, deposited in shallow marine environments, deltas, and the beds of braided and meandering rivers. In the early days, it was thought that the sand grains and surface tension would only allow 40 percent of the oil in the reservoir to be extracted; technology has now increased that to almost 60 percent—but that’s still a lot of oil left underground.

The engineering that goes into producing the fluids from a reservoir kilometers below the surface is very sophisticated, but one of the common problems it has to deal with is that the fluid is not the only thing produced at the surface. Very commonly, the sand grains are not completely glued together, the reservoir rock is not thoroughly lithified, and, along with the oil comes sand. The photo at right is an example where the engineering has not been as clever as it might be, and a pile of sand has accumulated under the drilling rig. But this is rare - sand management applies all kinds of technology for preventing the sand ever entering the well bore, and screening it out when it does - after all, the last thing needed is for sand and machinery to mix. And so the image above is from an advertisement for a high-tech geosciences and engineering consulting company that specialises, among many other activities, in controlling and managing sand production. But this managing and controlling is expensive, hence the allusion to the bottom line.