Unconventional Gas Recovery and Subsurface Water Mapping: A Relationship of Untapped Potential

摘要

Processes of unconventional gas recovery frequently have to deal with water issues. For the purposes of protecting both productivity and the environment, well operators must monitor the relationship between their extraction activity and the surrounding groundwater network. This is especially true in the case of hydraulic fracturing, when new fractures may facilitate communication with the local aqueous system. Well operators therefore have a vested interest in more effective methods for determining the size, shape, and flow patterns of subsurface water features. This paper introduces a new water imaging technology and considers its implications for unconventional gas recovery. The technology uses Controlled Source- Frequency Domain Magnetics (CS-FDM) to map and model underground water features. Its rapid and minimally invasive procedure has now been effectively implemented in a variety of ground-water projects. The results of those projects suggest that it possesses significant potential value for the natural gas industry. This paper will serve as the beginning of an overdue conversation about its merits and possibilities in that field. One of the most relevant applications of this technology has come in the area of improved oil recovery. By applying the technology’s water-mapping capabilities to oil reservoirs that have been flooded with water or steam, field operators have been able to quickly and accurately characterize the features of those reservoirs and thus develop more effective stimulation strategies. At this stage in the technology’s development, it is time to ask whether it can serve a similar function in unconventional gas production. That is, can a tight-gas feature or coal bed which has been filled with fracturing fluid, take advantage of CS-FDM’s capacity for reservoir characterization? The answer to that question could have major implications for production well placement, facilitating increased output and minimizing environmental impact, and also for evaluating hydraulic fractures