IMPACTS OF HYDRAULIC FRACTURING IN CALIFORNIA – AN OVERVIEW OF A COMPREHENSIVE SCIENCE ASSESSMENT
Wednesday, 16 December 2015
Poster Hall (Moscone South)
In 2013, California’s Senate Bill 4 required an independent science study to assess current and potential future hydraulic fracturing practices in California, and to evaluate potential impacts on water, air, seismicity, ecological systems, and health. The study, completed in July 2015, found that hydraulic fracturing currently supports about one quarter of California’s oil production, and is expected to continue to do so in the near future. California’s experience with hydraulic fracturing differs from that in other states because operators mostly conduct relatively shallow stimulations in relatively high-permeability reservoirs. The upside of this is that operations use relatively little water, but the downside is that in a few locations, fractures could extend into protected groundwater. The study also found that direct impacts of hydraulic fracturing appear small but have not been fully investigated in California. These direct impacts all stem from the use of stimulation chemicals and the study calls for precautionary limits on chemical use. Indirect impacts, which are not directly attributable to the stimulation activity but rather caused by oil and gas production enabled by stimulation, are likely more important. For example, underground injection of produced water from a hydraulically fractured reservoir causes problems common to all oil and gas production, such as the risk of inducing an earthquake or causing groundwater contamination. To date, there have been no reported cases of induced seismicity associated with produced water injection in California. However, it is difficult to distinguish California’s frequent natural earthquakes from those possibly caused by water injection. California also disposes of produced water from all oil and gas production in percolation ponds and injects some of this water into protected aquifers. These are serious issues, often tagged to hydraulic fracturing but actually common to all oil and gas production.