Drilling Fluid Additive Gets to the Core of Chile Project
A few years back, I had the opportunity to travel to the beautiful country of Chile, specifically the iron mining region of the Atacama Desert. This area is unique, in that extracting iron ore from Andesitic rock (a type of volcanic rock that was formed within this ancient Island Arc environment) is typically not feasible from an economic standpoint. This has been an exception to the rule and one of the few places in the world where this is being done successfully.
The group I was working with was contracted to extract in excess of 250,000 meters of rock core over the next couple of years in exploration efforts to expand the mining operation. It seemed like an overwhelming feat to accomplish! When I arrived to see the 15-plus diamond core rigs spread across the toe of the Andes in a spectacular panoramic view, I knew at that moment they meant business.
I first met with the geologists who were in the process of examining the cores to develop a cross section. They were friendly but expressed their frustration with the project. I thought it may have been the long hours on the wrong side of the mountains with nothing but a hand lens, scratch plate, bottle of hydrochloric acid and a notebook. As it turned out, their cores were highly weathered and fracturing easily. The drillers were handing them trays of “gravel” and they had a hard time identifying those samples. “What can be done?” they asked. We proceeded to the actual drilling operation itself to try and figure it out.
So here we reside in a desert with water coming from many kilometers away. It’s being introduced at a rapid rate because of issues with evaporation, fluid loss and production deadlines. The operators were concerned solely with fast production. They would run their rigs near their limits using nothing but water and some high-yield bentonite on occasion, with an inefficient mixing hopper. Inflatable pools that could hold about 500 gallons were being filled with mix water at two per rig. We did have a slightly elevated pH to start with, thanks to the groundwater source. But, it was apparent they needed to slow the bit down and use a polymer-based drilling fluid additive to aid in cooling and lubrication, without excessively increasing visco-sity, while being easily dispersible. An emulsified PHPA (partially hydrolyzed polyacrylamide) was sourced that we could mix easily into our bentonite slurry. The results were amazing, as expected, and the cores being extracted were much more competent! They could expect considerably less bit fatigue as an additional benefit over the course of this project and many others. The decrease in the rate of penetration was almost unnoticed and fluid loss was kept to a minimum. Most importantly, the unhappy geologists were now able to do their job more effectively.