Călin Dragoie, Energy Geologist, VP Geosciences with Chinook Consulting talks about several directions in which the oil and gas industry “can use and reuse the talent and expertise it has accumulated over the years”.
“Starting with drilling methods and continuing with data integration (well data and seismic processing data), then energy and heat production systems, the skills developed in the oil patch can be directly transferred in emerging industries related to renewable energy and alternative resources”.
Alternative resources refer to renewable energy, as well as other mineral resources that are used in the emerging green economy. There is geothermal energy, developed largely with the same methods used in oil and gas exploration and extraction. There is also lithium mining, and the option to extract it from reservoir brines, or extraction of phosphates through solution mining with water injection and brine production. Carbon dioxide capture and underground storage (CCUS) is a method used routinely for tertiary recovery in mature oil reservoirs. “I see these emerging developments as an opportunity to apply skill and technology perfected in the petroleum industry.”
Călin Dragoie presented the main types and flavors of geothermal developments. Conventional hydrothermal systems refer to the direct harvesting of hot water or steam from pressurized fluids in fractured and permeable rock encountered at shallow depths, often connected with hot springs. “Development in these scenarios is relatively straightforward, and widely used in select locations where the conditions are met, such as Iceland and California.”
Enhanced Geothermal Systems, EGS, refers to extraction and reinjection of a large volume of hot water from deep reservoirs, often stimulated with hydraulic fracturing (another technology developed in the unconventional hydrocarbon industry), to achieve large water volumes. “Reservoir evaluation and mapping have to be very precise for this type of development, to achieve the large water discharges needed to make these systems viable. We can also mention superhot rock geothermal, envisioned for high temperature and high-pressure settings, where water resides in the supercritical phase (upwards of 375 degrees Celsius). “Energy potential is very large, but so are technical challenges. I will not discuss this type here, as I don’t believe there is much applicability in Romania”, Călin Dragoie said.
Finally, Advanced Geothermal Systems (AGS) are closed-loop systems that harvest heat rather than reservoir water. These systems do not require hydraulic stimulation and generally target hot and dry formations, rock layers with low porosity and permeability, or even impermeable rock. “We prefer closed-loop geothermal systems for they hold a few advantages. Among these, there is the drastically reduced geological risk, as it does not target reservoir fluids or porous/permeable layers; they eliminate the need for fracking (and the accompanying community backlash this entails), and there is no parasitic load, as the fluid is moved through the loop based on thermosiphon effect. There are other, technical, challenges, Călin Dragoie explained. “We have to drill complex well geometry – but herein lies our expertise), in Chinook”.
Oil and gas operators often own or lease infrastructure that can be reused and recycled in the quest for renewables and alternative resources considers the expert. “Well leases can be reused for drilling new wells, or for deepening or enlarging existing wells for geothermal energy extraction. Pipelines can be reused: oil pipelines to transport water for district heating, natural gas pipelines to transport hydrogen (up to 10% concentration by volume without any changes). However, the most valuable asset is a highly skilled workforce, that is ready to deploy transferable skills towards new developments in the geothermal energy sector or the exploitation of alternative energy sources.”