Drilling Wells: Not Just for Oil & Gas

Drilling Wells: Not Just for Oil and Gas

Perhaps many people are unaware that wells are drilled for more ‘products’ than oil, natural gas, and natural gas liquids like propane and butane. Wells are also drilled for geothermal energy development, both shallow and deep geothermal. Wells are drilled for salt – Morton Salt has been drilling them for many years. One company is even evaporating salt water from old wells in West Virginia to sell what they see as specialty salts with desirable flavors! Wells are drilled for food grade CO2. One gas field near Charleston, West Virginia, the Indian Creek Field, produced fairly even amounts of natural gas and CO2 from the Silurian Tuscaroras Sandstone formation. The gas was produced for energy and CO2 was sold to Coca Cola. Wells are also drilled to sequester CO2 from power plants and other sources. Some CO2 is injected for enhanced oil recovery (EOR) and some for enhanced coal bed methane recovery (ECBM). Otherwise it is injected into deep saline brine-bearing formations for long-term permanent storage in a supersaturated state. Helium from drilled wells has been produced. Salt water from saline formations has been produced as a source of road salt. Currently wells are being drilled for lithium that is extracted from brines. The same can be done in some places for some rare earth elements. As global lithium demand is set to double due mainly to the upcoming EV revolution, there will be significantly more drilling for lithium. Even all oil and gas wells are not production wells. Some are wells drilled for injection of water, CO2, or chemicals for enhanced oil recovery. Some may be horizontal wells drilled in gas storage fields to increase deliverability. As we saw with the BP Deepwater Horizon disaster a well may be drilled as a ‘relief well’ in order to divert pressured hydrocarbons from a leaking well. Of course, wells are drilled for freshwater all over the world as well. There are also wells drilled for disposal of oilfield brines and in rare cases, for disposal of hazardous wastes. Another type of well drilled is a ‘monitoring well.’ These wells are typically drilled near landfills or near contaminated or potentially contaminated groundwater in order to monitor any new contamination or movement of known contaminant plumes.

Most oil and gas wells drilled now are drilled horizontally in order to make significantly more direct contact with target reservoir zones. Wells are also drilled directionally to access zones if the surface directly above is off limits. Horizontal wells may also be drilled to increase deliverability in storage fields, to increase injectable volumes of CO2 for sequestration, or to increase hot water volumes for geothermal applications. Currently an experimental geothermal well is being drilled into very hot deep rocks in Iceland heated with basaltic lavas, however, I don’t think that one is a horizontal well. Boreholes are drilled directionally and horizontally in order to place pipelines and cables under bodies of water or other surface obstructions. Test wells are drilled to get depths to rock units for surveying purposes or to map rock beds, mineral deposits, ores, or coals. Test boreholes are also drilled to assess site suitability for landfills and for large structures as part of geotechnical investigations.