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Title: Water issues overshadow Powder River coal gas play


Short communication.

Publication Date:
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Oil and Gas Journal; Journal Volume: 105; Journal Issue: 4
Country of Publication:
United States

Citation Formats

Petzet, A. Water issues overshadow Powder River coal gas play. United States: N. p., 2007. Web.
Petzet, A. Water issues overshadow Powder River coal gas play. United States.
Petzet, A. Mon . "Water issues overshadow Powder River coal gas play". United States. doi:.
title = {Water issues overshadow Powder River coal gas play},
author = {Petzet, A.},
abstractNote = {Short communication.},
doi = {},
journal = {Oil and Gas Journal},
number = 4,
volume = 105,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
  • Coal bed natural gas (CBNG) produced water is usually disposed into nearby constructed disposal ponds. Geochemistry of produced water, particularly trace elements interacting with a semiarid environment, is not clearly understood. The objective of this study was to collect produced water samples at outfalls and corresponding disposal ponds and monitor pH, iron (Fe), aluminum (Al), chromium (Cr), manganese (Mn), lead (Pb), copper (Cu), zinc (Zn), arsenic (As), boron (B), selenium (Se), molybdenum (Mo), cadmium (Cd), and barium (Ba). Outfalls and corresponding disposal ponds were sampled from five different watersheds including Cheyenne River (CHR), Belle Fourche River (BFR), Little Powder Rivermore » (LPR), Powder River (PR), and Tongue River (TR) within the Powder River Basin (PRB), Wyoming from 2003 to 2005. Paired tests were conducted between CBNG outfalls and corresponding disposal ponds for each watershed. Results suggest that produced water from CBNG outfalls is chemically different from the produced water from corresponding disposal ponds. Most trace metal concentrations in the produced water increased from outfall to disposal pond except for Ba. In disposal ponds, Ba, As, and B concentrations increased from 2003 to 2005. Geochemical modeling predicted precipitation and dissolution reactions as controlling processes for Al, Cu, and Ba concentrations in CBNG produced water. Adsorption and desorption reactions appear to control As, Mo, and B concentrations in CBNG water in disposal ponds. Overall, results of this study will be important to determine beneficial uses (e.g., irrigation, livestock/wildlife water, and aquatic life) for CBNG produced water in the PRB, Wyoming. 18 refs., 4 figs., 3 tabs.« less
  • Development of coal-bed natural gas (CBNG) in the Powder River Basin, Wyoming, has increased substantially in recent years. Among environmental concerns associated with this development is the fate of groundwater removed with the gas. A preferred water-management option is storage in surface impoundments. A study was conducted on changes in water and sediment chemistry as water from an impoundment infiltrated the subsurface. Sediment cores were collected prior to operation of the impoundment and after its closure and reclamation. Suction lysimeters were used to collect water samples from beneath the impoundment. Large amounts of chloride (12,300 kg) and nitrate (13,500 kgmore » as N), most of which accumulated naturally in the sediments over thousands of years, were released into groundwater by infiltrating water. Nitrate was more readily flushed from the sediments than chloride. If sediments at other impoundment locations contain similar amounts of chloride and nitrate, impoundments already permitted could release over 48 x 10{sup 6} kg of chloride and 52 x 10{sup 6} kg of nitrate into groundwater in the basin. A solute plume with total dissolved solid (TDS) concentrations at times exceeding 100,000 mg/L was created in the subsurface. TDS concentrations in the plume were substantially greater than those in the CBNG water (about 2300 mg/L) and in the ambient shallow groundwater (about 8000 mg/L). Sulfate, sodium, and magnesium are the dominant ions in the plume. The elevated concentrations are attributed to cation-exchange-enhanced gypsum dissolution. As gypsum dissolves, calcium goes into solution and is exchanged for sodium and magnesium on clays. Removal of calcium from solution allows further gypsum dissolution.« less
  • The high price of gas may trigger resumption of dissolved gas production from the Po River Delta, stopped in the early 1960s because of excessive subsidence. A contributing factor leading to a reexamination of the problem is the Japanese experience with dissolved gas production in which the injection of produced water separated from the gas overcame the subsidence problem. Additional impetus comes from the present Italian tendency to exploit marginal resources. This is particularly true of natural gas because an increasing percentage of the Italian energy requirement is being satisfied by gas, and the forecast is that this trend willmore » continue.« less
  • An investigation of speciated mercury transformation with the addition of hydrogen bromide (HBr) at elevated temperatures was conducted in a slipstream reactor with real flue gas atmospheres. Test results indicated that adding HBr into the flue gas at several parts per million strongly impacted the mercury oxidation and adsorption, which were dependent upon temperature ranges. Higher temperatures (in the range of 300-350 C) promoted mercury oxidation by HBr addition but did not promote mercury adsorption. Lower temperatures (in a range of 150-200 C) enhanced mercury adsorption on the fly ash by adding HBr. Test results also verified effects of fluemore » gas atmospheres on the mercury oxidation by the addition of HBr, which included concentrations of chlorine and sulfur in the flue gas. Chlorine species seemed to be involved in the competition with bromine species in the mercury oxidation process. With the addition of HBr at 3 ppm at a temperature of about 330 C, the additional mercury oxidation could be reached by about 55% in a flue gas atmosphere by burning PRB coal in the flue gas and by about 20% in a flue gas by burning bituminous coal. These are both greater than the maximum gaseous HgBr2 percentage in the flue gas (35% for PRB coal and 5% for bituminous coal) by thermodynamic equilibrium analysis predictions under the same conditions. This disagreement may indicate a greater complexity of mercury oxidation mechanisms by the addition of HBr. It is possible that bromine species promote activated chlorine species generation in the flue gas, where the kinetics of elemental mercury oxidation were enhanced. However, SO{sub 2} in the flue gas may involve the consumption of the available activated chlorine species. Thus, the higher mercury oxidation rate by adding bromine under the flue gas by burning PRB coal may be associated with its lower SO{sub 2} concentration in the flue gas. 39 refs., 8 figs., 4 tabs.« less
  • Excessive water production (more than 7000 bbl/month per well) from many coalbed methane (CBM) wells in the Powder River Basin of Wyoming is also associated with significant delays in the time it takes for gas production to begin. Analysis of about 550 water-enhancement activities carried out during well completion demonstrates that such activities result in hydraulic fracturing of the coal. Water-enhancement activities, consists of pumping 60 bbl of water/min into the coal seam during approximately 15 min. This is done to clean the well-bore and to enhance CBM production. Hydraulic fracturing is of concern because vertical hydraulic fracture growth couldmore » extend into adjacent formations and potentially result in excess CBM water production and inefficient depressurization of coals. Analysis of the pressure-time records of the water-enhancement tests enabled us to determine the magnitude of the least principal stress (S{sub 3}) in the coal seams of 372 wells. These data reveal that because S{sub 3} switches between the minimum horizontal stress and the overburden at different locations, both vertical and horizontal hydraulic fracture growth is inferred to occur in the basin, depending on the exact location and coal layer. Relatively low water production is observed for wells with inferred horizontal fractures, whereas all of the wells associated with excessive water production are characterized by inferred vertical hydraulic fractures. The reason wells with exceptionally high water production show delays in gas production appears to be inefficient depressurization of the coal caused by water production from the formations outside the coal. To minimize CBM water production, we recommend that in areas of known vertical fracture propagation, the injection rate during the water-enhancement tests should be reduced to prevent the propagation of induced fractures into adjacent water-bearing formations.« less