HR: 0830h
AN: H41C-1017    [PDF]
TI: Coalbed Methane Co-Produced Water Budget at a Storage Impoundment Site, Beaver Creek Drainage, Powder River Basin, Wyoming
AU: * Payne, A A
EM: apayne@uwyo.edu
AF: Department of Geology and Geophyics, University of Wyoming PO Box 3006, Laramie, WY 82071 United States
AU: Saffer, D M
EM: dsaffer@uwyo.edu
AF: Department of Geology and Geophyics, University of Wyoming PO Box 3006, Laramie, WY 82071 United States
AU: Wheaton, J R
EM: jwheaton@mtech.edu
AF: Montana Bureau of Mines and Geology, 1300 N. 27th St, Billings, MT 59101 United States
AU: Bierbach, S
EM: sbierbach@yahoo.com
AF: Montana State University-Billings, 1500 University Drive, Billings, MT 59101 United States
AB: Rapid coalbed methane (CBM) development in the Powder River Basin, Wyoming, has resulted in a dramatic increase in the number of producing wells, from less than 300 in 1997 to more than 10,000 in 2002, with as many as 40,000 new wells projected to be drilled during the next decade. CBM development involves the co-production of large volumes of coalbed water, which is most commonly discharged to impoundments. Little is known about the potentially significant effects that this co-produced water may have on shallow aquifers and water budgets. A small study site (1600 meters in length) was chosen in the Beaver Creek drainage (a tributary to the Powder River) to quantify the fate of CBM water. Discharge into two in-channel infiltration impoundments (areas of 4000 m$^{2}$ and 10,500 m$^{2}$) began in November, 2002. We installed monitoring wells at three locations-upstream, between, and downstream of the ponds. We emplaced a series of v-notch weirs between and dowstream of the ponds to quantify conveyance losses, and constructed a floating pan in one impoundment to measure evaporation. Over the study period from July 23 to August 21, 2003, we established a water budget from daily coalbed water production, flow measurements, and evaporation data. Water production from five wells into the two ponds averaged 647 L/min, or about 4500 bbl/day. Mean evaporation from the ponds and stream channel was 102 L/min. Infiltration determined by differences in water production and streamflow plus evaporation loss indicate an average infiltration of 240 L/min in the ponds, and 97 L/min within 1100 meters of investigated stream channel. Approximately 52% of the CBM co-produced water infiltrated, 16% was lost to evaporation, and 32% left the study area as surface water. Mean infiltration rates within the ponds ranged from 0.07 cm/hr in the smaller upstream pond to 0.1 cm/hr in the larger pond. In the middle sections of the stream channel, infiltration rates were about 0.7 cm/hr. Directly below the downstream pond, the infiltration rate was 0.3 cm/hr, slightly less than that determined for other streambed sections. In the most dowstream section of stream channel, the infiltration rate was 1.1 cm/hr. Well water levels in a control area unaffected by CBM water dropped by 18.3 cm over the study duration, while levels dropped only 6.1 cm between the ponds, and 12.2 cm below both ponds. Preliminary results suggest potentially significant variations in infiltration rates between the pond and stream settings. The response of the shallow aquifer water table also appears to vary within the study area.
DE: 1803 Anthropogenic effects
DE: 1836 Hydrologic budget (1655)
DE: 1857 Reservoirs (surface)
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting