Friday, October 28, 2011
An energy company generously allowed several students and me to watch a perforating and hydraulic fracturing operation at a vertical Woodford Shale gas well today. (After drilling and casing a well, the company isolates and punches holes in (perforates) the portions of the well and casing that will be fractured. This allows acid, water, chemicals, and proppant to move into the shale around the casing when pumped at high pressure down the well.) Several things struck me. First, I was surprised by the density of the operation. The site was small, but the fracturing service company had managed to pack a menagerie of complicated industrial equipment onto a postage stamp of dirt and gravel in the midst of tree-lined agricultural fields. The machine used to pump the fracturing fluid at high pressure down the well involves a maze of heavy pipes, valves, and gauges all packed together on what appears to be a mobile trailer bed. But they don't really rest on the bed; the web of pipes themselves seem to form a compact, moving component. It's like a huge pump station on wheels. And that was just one piece of equipment. A range of trailers, trucks, and other machinery, most of which seemed to have diesel engines, chugged away as employees first perforated very small portions of the well and casing (at a depth of more than 12,000 feet), reeled up and depressurized the perforating gun, pressure tested the well, applied an acid treatment, and then pumped various mixtures of water, chemicals, and sand down the well to fracture and prop open the fractures in the shale. The engines around the site created a constant, low-level roar, although we could still hear the explanations of processes on site as they unfolded.
Second, I was surprised by the number of computers. I had known that employees monitored the operation on a variety of computer screens in a trailer, but I was interested to see the complex program used. Charts of numbers ran like tickers on several screens, showing updated depths, pressures, and rates of acid, water/chemical, or proppant application, among other data, and several graphs ran simultaneously on other screens. The chemicals all sat in big plastic tanks outside (each approximately the size of a large, squat refrigerator) surrounded by metal wire and connected to thick rubber hoses (Goodyear, for example) lined with a metal mesh. They each had a prominent label attached. The acid tanks--thick metal boxes that could hold at least two or three refrigerators, probably--sat on another side of the site. They, too, were attached to big industrial hoses. There were small pools or piles of things at a few points on the site--a bit of sand or resin proppant here, a small, unidentified puddle of something else there. As the perforating gun was being pulled up out of the wellbore, drops of liquid fell on us from the cable above the wellhead. It was whitish; I guessed that it may have been the salty water that comes up naturally out of the formation. None of this, although it was really interesting, seemed too eventful. I imagined how the situation could potentially get more eventful if things went wrong--if the well hadn't been cased correctly, for example, or if a chemical spilled out of the hose while being transferred from a truck to a tank. As it was, though, I felt like I was in the middle of small yet complex and quite busy industrial operation that had suddenly sprung up in a rural area, and this operation also happened to be drilling, perforating, and fracturing things at 12,000-foot depths. The 12,000-foot depth thing still gets me every time. We have to drill that far down now to get to fuel? Really? A final surprise: the mobile food truck--like one of those fancy things in hip urban downtowns (minus the blatantly artistic paint)--that rolled up to the site to serve meat, potatoes, hot tortilla soup, salad, and banana pudding. (We were told that they don't eat like that every day, but some enterprising chef certainly has hatched a smart business plan for the middle of gas country.)