Old Oilfields vs. New Homes, Wells Case Studies, Proposed Solutions

Transcription

1 Old Oilfields vs. New Homes, Wells Case Studies, Proposed Solutions Patricia Billingsley, Brownfields Manager, Oklahoma Corporation Commission John Harrington, Director of Water Resources, Association of Central Oklahoma Governments

2 Background The Corporation Commission has had many complaints of water well pollution from homeowners over the past 20 years Both suburban and rural In and near oilfields mostly older oilfields with activity initiated pre-1980, when modern regulations began Sometimes petroleum, most often salinity We now understand enough about how these problems occur to propose prevention solutions

3 Example 1 - Recent Case In a fairly new gated community in NW OKC, a recent homebuyer complained of salty well water. Soon after, her neighbors were also complaining Since this was a historic oilfield area, our Field Inspector sampled their water wells. Later we learned that two original subdivision homeowners had had bad wells in their backyard, with later new wells in the front yards. Red Flag! We were only able to get partway downhole to sample one of these UNPLUGGED backyard wells.

4 Sampling Results Wells ~300 deep; only got to ~150 B backyard SO4 TDS or Na/Cl Who Na ppm Cl ppm ppm TotlSolSalts Z L C D N B Frontyard B Backyard 1600 Exceeds Chloride secondary drinking water standards Na/Cl Ratio <0.6 indicates oilfield source Sulfate SO4 from natural BaSO4, which makes Rose Rocks

5 Oilfield Site Location

6 WEST EDMOND OIL FIELD CIRCA 1945

7 Where there were Oilfield Tank, now we have New Homes

8 1941 Aerial Showing Drill Rigs, Pits Dry salty pit Drill rig shadows Pit with water Oil Well Spots

9 Old Pits & Wells, Modern Air Photo Oil Well Spots Oil Well Spots Pit s

10 Oilfield Brines This Site is in the old Edmond oilfields area. The USGS database of Produced Oilfield water had 90 samples. Brines are very saline, with chlorides up to 217,587 ppm. Very little water this saline in needed to pollute fresh water!

11 Geophysics At The Surface WELLS WITH HIGH CHLORIDE READING RED/YELLOW = LOW RESISTANCE = POOR WATER QUALITY GEOPHYSICAL ARRAY CF03 GEOPHYSICAL ARRAY CF03 ABANDONED WELLS WITH POOR WATER QUALITY BLUE/GREEN = HIGHER RESISTANCE = GOOD WATER QUALITY Geophysical Array CF03

12 Geophysics 3D, both saline plumes ANOMALY AT D HOUSE ANOMALY AT B HOUSE UNPLUGGED WELLS EXISTING DOMESTIC WELLS

13 Geophysics Linear Saline Plume, Backyard to East STAKE LOCATIONS SALT WATER PLUME Geophysical Array CF03 Resistivity Values <= 1 ohm-meter Depth ~ 20 Feet

14 Geophysics, IP METAL! Was A Gathering Line With a Hole STAKE LOCATIONS METAL (Now Rust) HOLE - PIPELINE BREAK Geophysical Array CF03 IP Induced Potential Values > 100 ms Depth ~ 20 Feet

15 Shallow Geophysics on 1951 Aerial Photo Definite Scar LARGER LOW RESISTIVITY ANOMALY 2 nd LOW RESISTIVITY ANOMALY ABANDONED WELLS WITH POOR WATER QUALITY 1951 Aerial Photo

16 Old Aerials Scars Indicate Gathering Line System 1951 AERIAL PHOTO OIL/BRINE GATHERING LINES? PIPELINE GATHERING SYSTEM

17 30 FEET First Water Well What Happened Later Water Well SALT WATER IN PIPE HENNESSEY SHALE GARBER SANDSTONE AQUIFER

18 Conclusions Old (1940 s-80s) Oilfield Activity Caused This The open, surface to 300 deep gravel pack water well construction channeled pit/wellsite (spill) surface contaminants down into the Garber Aquifer. In effect, the water wells, by their standard design, have polluted themselves - and the aquifer Especially the unplugged backyard wells

19 Intermediate Solutions The city was persuaded to bring a water line into the subdivision, so the homeowners could connect to clean drinking water (at a $$ cost) - done; And Corp Comm s Brownfields program paid for, and OWRB oversaw, having now-unused water wells drilled out and plugged to prevent the spread of more contaminants down into the aquifer.

20 Another Example Saline Plume Moving S in Subdivision Former oilfield Pit(s) now Church complex

21 Leaking Pits Affected Deeper Groundwater Data Fresh Saline Deeper Aquifer Salinity Pit Model Processed Data Showing Inferred Groundwater Conditions

22 Edmond Thunderhead Hills Subdivision: groundwater pollution plume moving since 1990s through subdivision at 90 south per year, dozens of water wells being ruined Apparent Source: Old pits Special Bonus stream and reservoir Spring Creek Lake Arcadia

23 Similar Groundwater Quality Problems, Statewide

24 Oklahoma Aquifers

25 Historic OK Oil and Gas Fields

26 Corm Comm Has Taken > 2000 Groundwater/Well Samples Over The Last 20 Years Most of the samples were collected after a complaint or other problem, so The data is biased toward the bad Anions (e.g. Na, K, Ca), Cations (e.g. Cl, SO4), Nitrate, boron, Heavy Metals, Petroleum, etc.

27 Groundwater With Chloride Exceeds

28 Groundwater With Sodium Exceeds

29 Groundwater With Petroleum

30 Groundwater With Oilfield Ion Ratio

31 The Plan To Protect the Aquifers of Oklahoma From Similar OLD Oilfield Problems In The Future

32 Corp Comm is Mapping Old (pre 1980) wells on Oklahoma Aquifers, starting with the Central Oklahoma Aquifer : Before 1980, pit design, well plugging oversite, field inspection not as rigorous as after 1980 E.g. Regular Mechanical Integrity testing of well casing, lines, equipment was not required pre-1980

33 Arbuckle Simpson A Few O&G Areas

34 Oil Wells >16/sq mi, Central OK Aquifer

35 Wells & Towns on Central OK Aquifer

36 New Rules Request Made to OWRB In the mapped areas where wells, pits, and shallow pollutants are the most likely (old wells <1400 apart, >16 per square mile) New Rule requiring future water wells to be cased and cemented from the surface to 30 deep, with gravel pack allowed only BELOW that. This will help prevent shallow pollutants from entering the water wells and traveling down the gravel pack into the aquifer.

37 Where Town Planning May Come In ACOG Talks to Town Planners in COG Area? If you were a city planner, or a councilman representing voters, would you want soil pre-tested here BEFORE buildings get permitted? Moore Pre-testing of the groundwater before home or $$ City water wells are installed? N Norman