Figure
Figure S.3-8. Disposal method for produced water from hydraulically fractured wells during the first full month after stimulation for the time period 2011-2014 based on data from the DOGGR monthly production database. Note: Subsurface injection includes any injection into Class II wells, which include disposal wells as well as enhanced recovery wells used for water flooding and steam flooding (figure from Volume II, Chapter 2).
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Senate Bill 4 (SB 4) requires an independent study to assess current and potential future
well stimulation practices in California, including the likelihood that these technologies
could enable extensive new petroleum production in the state; impacts of well stimulation
technologies (including hydraulic fracturing, acid fracturing and matrix acidiz...
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Most unconventional oil and gas reservoirs contain some natural fractures, which play an essential role during reservoir reconstruction. Given the strong discontinuities in the displacement on both sides of the fracture as well as weak discontinuities in the pore fluid pressure, a novel three-dimensional seepage-stress coupling model using extended...
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Oilfield flowback and produced water (FPW) is a waste stream that may offer an alternative source of water for multiple beneficial uses. One practice gaining interest in several semi-arid states is the reuse of FPW for agricultural irrigation. However, it is unknown if the reuse of FPW on edible crops could increase health risks from ingestion of exposed food, or impact crop growth. A greenhouse experiment was conducted using wheat (Triticum aestivum) to investigate the uptake potential of select hydraulic fracturing additives known to be associated with health risks. The selected chemicals included acrylamide, didecyldimethylammonium chloride (DDAC), diethanolamine, and tetramethylammonium chloride (TMAC). Mature wheat grain was extracted and analyzed by liquid chromatography-triple quadrupole mass spectrometry (LC-QQQ) to quantify chemical uptake. Plant development observations were also documented to evaluate impacts of the chemicals on crop yield. Analytical results indicated that TMAC and diethanolamine had significantly higher uptake into both wheat grain and stems than control plants which were not exposed to the four chemicals under investigation. Acrylamide was measured in statistically higher concentrations in the stems only, while DDAC was not detected in grain or stems. Growth impacts included lodging in treated wheat plants due to increased stem height and grain weight, potentially resulting from increased nitrogen application. While analytical results show that uptake of select hydraulic fracturing chemicals in wheat grain and stems is measurable, reuse of FPW for irrigation in real world scenarios would likely result in less uptake because water would be subject to natural degradation, and often treatment and dilution practices. Nonetheless, based on the outstanding data gaps associated with this research topic, chemical specific treatment and regulatory safeguards are still recommended.
The potential hazards and risks associated with well-stimulation in unconventional oil and gas development (hydraulic fracturing, acid fracturing, and matrix acidizing) have been investigated and evaluated and federal and state regulations requiring chemical disclosure for well-stimulation have been implemented as part of an overall risk management strategy for unconventional oil and gas development. Similar evaluations for chemicals used in other routine oil and gas development activities, such as maintenance acidizing, gravel packing, and well drilling, have not been previously conducted, in part due to a lack of reliable information concerning on-field chemical-use. In this study, we compare chemical-use between routine activities and the more closely regulated well-stimulation activities using data collected by the South Coast Air Quality Monitoring District (SCAQMD), which mandates the reporting of both unconventional and routine on-field chemical-use for parts of Southern California. Analysis of this data shows that there is significant overlap in chemical-use between so-called unconventional activities and routine activities conducted for well maintenance, well-completion, or rework. A comparison within the SCAQMD shows a significant overlap between both types and amounts of chemicals used for well-stimulation treatments included under State mandatory-disclosure regulations and routine treatments that are not included under State regulations. A comparison between SCAQMD chemical-use for routine treatments and state-wide chemical-use for hydraulic fracturing also showed close similarity in chemical-use between activities covered under chemical disclosure requirements (e.g. hydraulic fracturing) and many other oil and gas field activities. The results of this study indicate regulations and risk assessments focused exclusively on chemicals used in well-stimulation activities may underestimate potential hazard or risk from overall oil field chemical-use.
We quantify the monetary market and non-market environmental benefits and costs of hydraulic fracturing in the 14 U.S. states whose oil and gas production is dominated by hydraulic fracturing. By far the largest market benefit is $75 billion ($46–$95 billion) in consumer surplus from lower natural gas prices to residential, commercial, and industrial consumers. There are also environmental benefits resulting from the switch by some electric utilities from coal to natural gas ($13.25 billion, range $3.9–$21.9 billion). However, there are also substantial environmental costs associated with hydraulic fracturing. These are dominated by $27.2 billion ($12.5–$41.95 billion) health damages from air pollution. Costs also include $3.8 billion ($1.15–$5.89 billion) in greenhouse gas emissions, $4 billion ($3.5–$4.45 billion) in wildlife habitat fragmentation, and $1 billion ($0.5–$1.6 billion) in pollution of private drinking water wells. Opportunity costs of water usage and property value losses are less than one-quarter of a billion dollars. The market and non-market benefits of hydraulic fracking are widespread geographically but many of the non-market costs are concentrated in the areas of drilling, creating a distributional disconnect that we believe drives much of the controversy over hydraulic fracturing.
