*Yousif K. Kharaka, James J. Thordsen, Evangelos Kakouros, and Gil Ambats

1. Environmental Impacts of Oil and Gas Exploration and Production: Ground Water Impacts at OSPER Sites, Osage County, Oklahoma *Yousif K. Kharaka, James J. Thordsen, Evangelos Kakouros, and Gil Ambats U. S. Geological Survey, Menlo Park, California, USA GSA Annual Meeting October, 2005 Financial support from DOE-NETL Drilling support from EPA-NRMRL Osage Nation Tribal Authorities U.S. Army Corps of Engineers

2. Distribution of Petroleum wells in Oklahoma, Osage County, & the study Area

3. Topics Discussed 1-  OSPER “A” site, Osage County, OK. 2-  Chemical & isotopic compositions of source & ground waters at OSPER “A” site. 3- Delineating the plume boundaries at “A”. 4- Processes--Mixing (brine, prec. & GW), ET & water-rock-bacterial interactions. 5- Future plans & concluding remarks.

4. OSPER “A” Site • Oil production (100,000 bbl) from shallow. Pennsylvanian sandstones started in 1912, mostly completed by 1937. • No site activity for 65-70 years. • No waterflooding at this site • All the produced water (~1million bbl) released to ground surface; petroleum initially collected at oil pit. • Deep erosion of northern part of the site

5. Geology Map Lower area (north) • steeper slope • prominent salt scar (~2 m deep) • salt (& gypsum) at surface Asphaltic pits • highly weathered oil • one pit contains relatively fresh tank sludge(?) Upper area (south) • gentle slope • tree kills from early(?) salt releases • revegetated with grasses

6. Photo by Ken Jewell, USEPA (Jan. 2004)

8. Sampling Trips to the Sites March 2001--- Source fluids from oil wells, GW, and Skiatook Reservoir. Surface pools at both sites. February 2002--- ~60 Geoprobe, auger and rotary wells drilled, cored, completed and sampled at and two sites. June 2002 --- Water level, conductance, and T measurements, followed by collection of ~40 water and a few oil samples. November 02 --- Drilling with geoprobe and sampling. March-April 03 ---Drilling (EPA auger) and sampling. January 2004 --- (9) deep wells (WRD air) at “A”, and sampling. May 2004 --- (4) deep (EPA auger) wells at “B”; sampling. February 2005 --- Water levels and sampling at both sites. September 2005 --- Weir discharges.

10. “A” site Stiff Diagrams

11. New wells (1/04) Traverse a-a’

12. Site A - a-a’ traverse (with tritium)[update 10/12/05] 4.2 4.2 9.9 6.9 1.2 1.7 1.4 0.1 1.0 0.3 Tritium (in T.U.)

13. 230 South North a-a’ traverse brine AE07 pits AE55 AA10 AA04 AE06 225 salt scar erosion AA02 ~5 ~20 Skiatook AA01 Lake 920 23 2,960 4.5 AA06 AE51 DRY 220 AA61 AE13 3,350 19 10,000 6,500 180 2,500 12,300 420 15,300 470 6,060 150 5,000 215 Altitude, in meters above sea level Skiatook Lake levels 6,230 96 ?? 9,840 504 high: 219.1 m (3/2004) low: 215.8 m (2/2003) 18,400 365 5,000 10,000 210 207 520 15,000 39 730 18,300 375 205 chloride (mg/L) sulfate (mg/L) 200 0 25 50 75 100 125 150 175 200 225 Distance along traverse, in meters

15. 230 c'' c c' Southwest Southeast salt scar erosion AA09 225 AA05 AA13 AA07 AA08 AA06 AA61 AE53 220 Skiatook Lake levels AE13 6,400 19 high: 219.1m (3/2004) 4,080 200 2,500 low: 215.8m (2/2003) 6,060 150 215 Altitude, in meters above sea level 1,460 1310 9,840 504 6,860 586 6,820 363 SO4 > Cl 18,400 365 53 363 5,000 53 394 210 SO4 > Cl 15,000 18,300 376 205 49 677 6,950 883 68 1,460 48 1,280 Chloride(mg/L) Sulfate (mg/L) 10,000 200 0 30 60 90 120 150 180 210 240 Distance along traverse, in meters W-E traverse

17. Mineral-Water Interactions for S at OSPERs

18. Summary and Conclusions At OSPER ‘A’ site: • GW plume (3,000-30,000 mg/l TDS) extends beyond the salt scarred area & intersects Skiatook Lake;3-D limits?? • The extent of inorganic and organic GW plumes are different. • Salt & organics from produced water releases still remain in soils and GW after 65+ years of natural attenuation. Future Plans Natural attenuation; solute transport (overland &GW); remediation. *** Environmental Geosciences, 2005, v. 12, No. 2 ***