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Improved Monitoring Techniques to Assess Groundwater Quality Near Sources of Contamination
Published in Rip G. Rice, Safe Drinking Water, 2017
A specialized use of aerial photography, and particularly historical photography acquired in the 1930s and 1940s, has been the identification of abandoned oil wells that could provide man–made pollution conduits into aquifers. The presence in the United States of more than 1.8 million active and abandoned wells underscores the importance of this concern. Initial efforts have demonstrated a very high discovery rate of abandoned wells using photos and the feasibility of pinpointing the well locations within six feet for ground investigations. Even in cases where county records indicate the presence of such abandoned wells, the records and available maps frequently are not sufficiently accurate to allow such pinpointing, or indeed even discovery in fields that are now overgrown.
Injection of Produced Wastewater
Published in Frank R. Spellman, Hydraulic Fracturing Wastewater, 2017
In the past, common practice was simply to walk away and forget about a well when it ran dry. Today, while dry or failing wells are still abandoned, we know that they must be abandoned with care (and not completely forgotten). An abandoned well can become a convenient (and dangerous) receptacle for wastes, thus contaminating the aquifer. An improperly abandoned well could also become a haven for vermin or, worse, a hazard for children. A temporarily abandoned well must be sealed with a watertight cap or wellhead seal. The well must be maintained so it does not become a source or channel of contamination during temporary abandonment.
Children’s Environmental Health Issues
Published in Herman Koren, Best Practices for Environmental Health, 2017
Drowning rates for all age groups of children are three times higher in rural areas than in urban areas. Rural areas tend to have more bodies of water which are unsupervised, including farm ponds, irrigation canals, and small streams. Also, liquid manure areas can easily become a place of drowning for the small, inexperienced child. Abandoned wells which are not properly secured create another potential hazard. Among older children, the consumption of alcohol before or during water activities leads to drowning.
Measurements show that marginal wells are a disproportionate source of methane relative to production
Published in Journal of the Air & Waste Management Association, 2020
Jacob A. Deighton, Amy Townsend-Small, Sarah J. Sturmer, Jacob Hoschouer, Laura Heldman
Methane emissions from marginal wells measured in our study are shown in Figure 1. The error bars represent the average normalized standard deviation of the CH4 emission rates derived from the CH4 samples taken from the outflow of the high-flow sampler. We found a skewed distribution of CH4 emission rates, indicating that only few of the wells measured are responsible for a majority of the emissions. Many of the wells (n = 22 out of 48) emitted 10 g h−1 or less. Twenty-seven percent (n = 13) of the wells measured emitted over 100 g h−1. The emission rates ranged from 0 g h−1 to 907 g h−1 with an average emission rate of 128 g h−1 and a median emission rate of 18 g h−1. The top four highest emitters, or 8% of the wells measured, were responsible for approximately 50% of the total CH4 emissions observed in the study. This pattern of skewed distribution of CH4 emissions has been found in previous studies of abandoned wells (Townsend-Small et al. 2016) as well as one previous study of active conventional wells (Omara et al. 2016) in the Appalachian Basin, and is characteristic of all natural gas systems nationally (Zavala-Araiza et al. 2015). The highest emitter in this study had an average emission rate of 906.7 g h−1. The wellhead had been damaged by a fallen tree, the natural gas gathering line was not present, and a valve was opened to vent the natural gas being produced. This well was measured three times over the course of the study (see further discussion below).
The characteristics of petroleum seepage in coal seams: a case study of Ordos Basin
Published in Petroleum Science and Technology, 2022
Jie Zhang, Jianjun Wu, Sen Yang, Wenyong Bai, Qingsong Zhuo
The scatter fitting curve of the seepage velocity over 30 months is shown in Figure 13. Overall, the petroleum pressure in the geological reservoir continuously increases toward the abandoned wells. The petroleum seepage velocity is also changing (Zhang, Chen, and Zhang 2017; Zhang et al. 2019). The seepage velocity includes three forms: low-speed non-Darcy seepage, Darcy seepage, and high-speed non-Darcy seepage. The initial stage of petroleum seepage is during the first 0 ∼ 2nd months. The petroleum seepage velocity is almost zero during this initial period. According to the seepage theory analysis, the petroleum pressure of the well is less than the starting pressure gradient, so the petroleum has no seepage movement in the coal seam. The wellhead is in a closed state with the enrichment of petroleum from geological reservoirs to abandoned petroleum wells, so the petroleum pressure is increasing. When the petroleum pressure of wells exceeds the starting pressure gradient in the coal seam, the petroleum seepage velocity in coal increases linearly with seepage time. The maximum seepage velocity can reach about 16 m/month, namely, from month 5 to 18 in the Figure 13. Because of increase in seepage pressure, the pore-fissure structure of the coal continues to expand and extend, and the resistance pressure of the coal pore-fissure to petroleum seepage decreases. Overall, as the coal permeability increases, the petroleum seepage velocity increases (Bai et al. 2019; Akhondzadeh et al. 2020; Lv, Ji, and Ren 2020). Therefore, when the seepage velocity reaches the maximum, the seepage form conforms to the low-speed non-Darcy seepage and Darcy seepage.