Subsurface Architecture for Closed Loop Geothermal Energy Production

Energy derived from a subsurface geothermal asset has traditionally involved the placement of one or more wellbores in a hot and water-bearing source formation of interest. Hot water is produced through one or more wells. Once the energy has been recovered from the source water, the then cooler water is reinjected into the source formation via dedicated disposal well, or a repurposed producer well. This technique has become standard in the industry and has been proven to be a reliable method of heat extraction, providing the conditions for source rock heat, producible water, permeability, etc. are amenable to the approach. The wellbores in the previous example interact with the source rock of interest and therefore interact with each other tangentially. But what if the wellbores could be placed subsurface with the same level of architectural precision and complexity as pipelines are currently installed above ground? Could enhanced geothermal production methods be unlocked if wellbores could directly interact with one another as well as the source rock in a manner that optimizes heat extraction? Could the installation of subsurface architecture through directional drilling unlock the potential of hot but dry formations, or make heat reservoirs with other poor production characteristics now viable? The reader will be introduced to advanced directional drilling methods related to magnetic ranging, a technique that allows for the precise downhole placement of wellbores. More specifically, this paper aims to educate the audience on wellbore intersection, close approach, and precise distancing. These techniques can and have been used in enhanced geothermal techniques, in addition to applications in the oil and gas, mining, and construction sectors. It is our intention to educate the reader to the economical and understood processes associated with magnetic ranging so that the technology introduced can be leveraged to unlock new or previously uneconomical geothermal plays.