Drilling Fluids: How Much Clay is Actually Left in Wyoming?
December 10, 2012
I can remember asking this column’s title question long before I started working for a bentonite company. It was during one of my first summer jobs working for a family friend who, among many other things, drilled water wells for the houses he built. Looking back on it now, it was a pretty well-rounded education I was getting in various construction trades. We would drill and construct a water well, dig a septic system, set up and pour the foundation slab, and build and trim the house. Then we put up a fence around the property if the owner so desired. Those steps involved many trades, but the most fascinating to me was drilling that well.
On one of those jobs, the bentonite company’s sales representative dropped by with the pump-house distributor and told us about the complete product line he sold and the benefits we would see if we used a few additives-it turns out he was right about those benefits, by the way. He also told us about how much bentonite was being sold into the drilling industry. This was the mid-1970s, and the oil field was extremely active at that time, as it is now. The figure he stated was in the millions of tons. I was astounded, so I asked him, “How much clay can there be left out there? You guys have been using the stuff for 50 years, and this drilling business is going to be around forever-what will we use when we run out of bentonite?”
The mud man nodded and said that even though the bentonite outfits had been mining the sodium clay of Wyoming for that long, the estimates of the day were that there were at least 30 years of high-yield clay left for the drilling business. He said that after 30 years everyone will be using polymers and specialty chemicals to drill with anyway.
Hey, wait a minute-long pause-that was more than 30 years ago! We must be on the verge of extinction! Hold on there, maybe not. In fact, when I am asked that question, as I was at a slurry school several months ago, my answer is very similar to the one that old mud man gave me about 30 years ago: based on the current claims, mining project plans and the historical and projected usage rates, we have domestically at least 30 years of high-yield clay reserves in the Wyoming region.
Why hasn’t there been a change in estimated reserves from 1975 to 2012? The answer to that question involves a large number of factors, but the essential explanation is that over the intervening years, most of the major bentonite companies have gotten very good at choosing the types of clay to reserve for particular industries. There are a number of different types and qualities of sodium bentonite mined in the greater Wyoming region and about a thousand different industries that need them. Most of these industries do not need the high-yielding clays that the drilling industry relies on. In fact, a high percentage of industries outside the drilling community prefer a much slower-yield Wyoming bentonite than we use, and since there are many grades of clay in a deposit, we can separate them for the various uses.
As far as determining our current reserves, our analysis of the deposits has become much more sophisticated over the years. Now, using refined digital imagery from exploration bores and GPS data, we can fine-tune our pit plans, taking into account all the available deposits. When planning new pits, we predetermine to a much larger extent the intended market for the clays we will be bringing to the mill from a new excavation. In this way we can much more accurately forecast reserves for a particular industry. Also, we are able now to go back into previously mined areas and, using the new digital exploration tools and GPS data, can add thousands of tons of various grades-including high-yielding clays-to our reserves, to our current mine plan, or for future mining.
There are also large reserves of high-quality bentonite that we are exploring elsewhere on the planet, and they are adding to our total reserves. This news is very important for North American drillers and for drillers working on other continents. When a driller in Australia, for example, uses drilling gels made from high-yield Australian clay, he leaves more of the Wyoming reserve for domestic use. The advantage for the Aussie working in that beautiful country is that his drilling costs go down considerably because he does not have to pay the freight from the U.S. He gets an excellent drilling product in the bargain.
All in all, our bentonite reserve picture here at home and globally is a strong one. We are adding to them annually and are becoming very efficient in using the right clay for the right job. So the mud man I spoke to on that job in the summer of ’75 wasn’t entirely wrong; we did have enough bentonite to get us into the 21st century, and, as much as I appreciate the benefits of always using the right additives in the drilling fluid mix to build the most effective system, I think we will be using bentonite as the base for our drilling mud for a long time to come. So if one of my grandchildren gets a chance to ask this old mud man, “How much clay can be left out there?” I can confidently say that it will be there for his generation and beyond. ND