James I. Sams

Using HEM surveys to evaluate disposal of by-product water from CBNG development in the Powder River Basin, Wyoming

Production of methane from thick, extensive coal beds in the Powder River Basin of Wyoming has created water management issues. Since development began in 1997, more than 650 billion liters of water have been produced from approximately 22,000 wells. Infiltration impoundments are used widely to dispose of by-product water from coal bed natural gas (CBNG) production, but their hydrogeologic effects are poorly understood. Helicopter electromagnetic surveys (HEM) were completed in July 2003 and July 2004 to characterize the hydrogeology of an alluvial aquifer along the Powder River. The aquifer is receiving CBNG produced water discharge from infiltration impoundments. HEM data were subjected to Occam’s inversion algorithms to determine the aquifer bulk conductivity, which was then correlated towater salinity using site-specific sampling results. The HEM data provided high-resolution images of salinity levels in the aquifer, a result not attainable using traditional sampling methods. Interpretation of these i...

Spatial and Temporal Characteristics of Historical Oil and Gas Wells in Pennsylvania: Implications for New Shale Gas Resources.

Recent large-scale development of oil and gas from low-permeability unconventional formations (e.g., shales, tight sands, and coal seams) has raised concern about potential environmental impacts. If left improperly sealed, legacy oil and gas wells colocated with that new development represent a potential pathway for unwanted migration of fluids (brine, drilling and stimulation fluids, oil, and gas). Uncertainty in the number, location, and abandonment state of legacy wells hinders environmental assessment of exploration and production activity. The objective of this study is to apply publicly available information on Pennsylvania oil and gas wells to better understand their potential to serve as pathways for unwanted fluid migration. This study presents a synthesis of historical reports and digital well records to provide insights into spatial and temporal trends in oil and gas development. Areas with a higher density of wells abandoned prior to the mid-20th century, when more modern well-sealing requirements took effect in Pennsylvania, and areas where conventional oil and gas production penetrated to or through intervals that may be affected by new Marcellus shale development are identified. This information may help to address questions of environmental risk related to new extraction activities.

Using Airborne Thermal Infrared Imagery And Helicopter EM Conductivity To Locate Mine Pools and Discharges In The Kettle Creek Watershed, North Central Pennsylvania

The Kettle Creek watershed contains 50–100-year-old surface and underground coal mines that are a continuing source of acid mine drainage (AMD). To characterize the mining-altered hydrology of this watershed, an airborne reconnaissance was conducted in 2002 using airborne thermal infrared imagery (TIR) and helicopter-mounted electromagnetic (HEM) surveys. TIR uses the temperature differential between surface water and groundwater to locate areas where groundwater emerges at the surface. TIR anomalies located in the survey included seeps and springs, as well as mine discharges. In a follow-up ground investigation, hand-held GPS units were used to locate 103 of the TIR anomalies. Of the sites investigated, 26 correlated with known mine discharges, whereas 27 were previously unknown. Seven known mine discharges previously obscured from TIR imagery were documented. HEM surveys were used to delineate the groundwater table and also to locate mine pools, mine discharges, and groundwater recharge zones. These sur...

Measurement of methane emissions from abandoned oil and gas wells in Hillman State Park, Pennsylvania

ABSTRACT Abandoned oil and gas wells, improperly plugged or unplugged, present a risk to current and future oil and gas development because they provide a potential pathway for unwanted gas and fluid migration to the surface. The appropriate emission factor for gaseous emissions from these wells is uncertain, as a limited number of studies have reported abandoned wells as a methane emissions source. A helicopter-based survey that mapped methane concentration and located wells by detecting magnetic anomalies was conducted in Hillman State Park in southwestern Pennsylvania. Although well finding via aerial survey was successful, elevated methane concentrations due to emissions from wells in the survey area were not detected by helicopter as abandoned wells were likely too small a source of methane to detect from elevations that helicopters fly at (tens of meters). Measurement of methane emission rates from 31 wells were collected using several techniques that are compared and evaluated for their effectiveness: Hi Flow sampler, field-portable flame ionization detector, infrared camera, dynamic flux chamber and bag sampling. Nine of the 31 wells were buried; average methane flux for these wells was not statistically different from the background. Mass flow rate from the remaining 22 wells ranged from non-detection (less than 0.09 kg CH4/day) to 4.18 kg CH4/day with a mean of 0.70 kg/well/day (median of 0.24 kg CH4/day/well) and a sample standard of error of 0.21 kg CH4/well/day. This emission factor, while not intended for exclusive use in developing a methane emissions inventory for abandoned oil and gas wells, contributes to the growing amount of methane emissions data for this source category. The results from the aerial survey, ground-based well location verification and emissions measurements, and the evaluation of measurement approaches described here, provide a comprehensive characterization of abandoned wells in one field that can inform future measurement studies.

Passive detection of Pb in water using rock phosphate agarose beads

In this study, passive detectors for Pb were prepared by immobilizing powdered rock phosphate in agarose beads. Rock phosphate has been used to treat Pb-contaminated waters and soil by fixing the metal as an insoluble pyromorphite mineral. Under lab conditions, Pb was rapidly adsorbed from aqueous solution by the beads over time, consistent with the acidic dissolution of rock phosphate, the precipitation of pyromorphite within the pore space of the agarose gel matrix, and surface exchange reactions. Net accumulation of Pb occurred when beads were exposed to simulated periodic releases of Pb over time. Under field conditions, beads in mesh bags were effective at detecting dissolved Pb being transported as surface runoff from a site highly contaminated with Pb. Rates of Pb accumulation in beads under field conditions appeared to be correlated with the frequency of storm events and total rainfall. The rock phosphate agarose bead approach could be an inexpensive way to carry out source-tracking of Pb pollution, to verify the successful remediation of sites with Pb-contaminated soil, and to routinely monitor public water systems for potential Pb contamination.

USING AIRBORNE ELECTROMAGNETIC SURVEYS TO IDENTIFY POTENTIAL HAZARDS AT COAL WASTE IMPOUNDMENTS: EXAMPLES FROM WEST VIRGINIA

Mine impoundments have in the past been a cause of catastrophic loss of life and destruction of property. To characterize this potential hazard, helicopter-mounted electromagnetic (HEM) surveys of coal waste impoundments were completed to identify fluid saturated zones within coal waste and to delineate the paths of filtrate fluid flow beneath the decant pond, through the embankment, and into adjacent strata or receiving streams. We also attempted to identify flooded mine workings underlying or spatially adjacent to the waste impoundment areas. In this effort, the National Energy Technology Laboratory of the United States Department of Energy (http://www.netl.doe.gov) conducted HEM surveys of 14 coal waste impoundments in southern West Virginia. Five electromagnetic frequencies were used in our surveys (385, 1700, 6536, 28120 and 116300 Hz) and processed using different inversion techniques to determine apparent conductivity depth images (CDI). Follow-up, ground-based resistivity surveys verified the results of the HEM survey. Overall, HEM and ground-based geophysical surveys proved to be effective in delineating the phreatic surface, determining seep locations, locating blockage in engineered drains, imaging areas of unconsolidated slurry, locating areas where process water has invaded adjacent aquifers, potentially depicting the possible location of flooded underground mine workings, locating infiltration zones into the abandoned mines and determining the spatial extent of impoundment impact.

THE USE OF AIRBORNE MAGNETIC AND EM CONDUCTIVITY SURVEYS TO LOCATE GROUNDWATER FLOW PATHS AT THE SULPHUR BANK MERCURY MINE SUPERFUND SITE 1

Airborne magnetic and electromagnetic (EM) conductivity surveys were conducted at the Sulphur Bank Mercury Mine Superfund Site near Clearlake, California to identify potential pathways for groundwater flow. The total field magnetic survey identified four fault zones that are potential conduits for mercury-contaminated, groundwater flow out of the flooded pit of the abandoned Sulphur Bank Mercury Mine. The location of the four fault zones was corroborated by the EM conductivity survey, which also provided evidence that the fault zones contained highly conductive water, either from deep, geothermal origin or from meteoric water made acidic by weathering of sulfide minerals and oxidation of H2S-bearing gases. This information was used to locate groundwater- monitoring wells and to provide assurance that all potential avenues for groundwater leaving the site were identified.