Use of Non-Invasive Near-Surface Geophysics for Managing Brine Releases

Transcription

1 Use of Non-Invasive Near-Surface Geophysics for Managing Brine Releases Presented by: Brent W. Barker, Staff Geophysicist Remediation Technologies Symposium 2012 Imagine the result

2 Co-Authors Boyce L. Clark, Principal Scientist- Geochemistry & Geophysics. Mary K. Gilkison, Principal Geologist. Eric B. Rogoff, Principal Geologist.. 2

3 Brine or Produced Water Includes water from subsurface formations and water injected into formations that is brought to the surface during oil and gas production. Can have a salt content up to 4 times higher than seawater.

4 Why the concern about produced water? Produced water accounts for the largest waste stream volume associated with oil and gas production. Area impacted by release of produced water Salt water is toxic to plant life. Salt water spills affect the ability of the impacted soil to resist erosion. Impacted fresh water aquifers are difficult to restore and damages awarded for groundwater impacts can be substantial.

5 Total Dissolved Solid (TDS) content of produced water from US oil and gas wells. (from USGS produced water-database) 5

6 Oklahoma Site: Near-Surface Geophysical Survey Water transfer line failure resulted in surface spill of >1,000 barrels (>42,000 gallons) of produced water. Chloride concentration approx. 160,000 ppm. 6

7 Oklahoma Site: Extent of Visual Impacts and Resistivity Line Locations Visual extent of dead vegetation Release Point 7

8 Oklahoma Site: Near-Surface Geophysical Survey Objectives Non-invasively locate the vertical and lateral extent of brine impacts. Assess whether the brine release extended into a deep, bedrock aquifer beneath the shallow groundwater zone. Determine optimal location for recovery well installations. 8

9 Release Delineation Surface Geophysical Method Electromagnetics (EM) Limited depth of penetration to approximately 5 feet below ground surface. EM-38 Evaluates soil electrical conductivity. High-TDS plume delineation in the shallow subsurface.

10 Greater depth of penetration than an electromagnetic (EM) Survey. Evaluates resistivity/conductivity of soil & groundwater. Geologic mapping (lithologic contacts, bedrock features) High-TDS plume delineation Release Delineation Surface Geophysical Method Electrical Resistivity Imaging (ERI) Resistivity Meter and Relay Box Electrode 2-D Survey Line

11 Technology Electrical Resistivity DC current is introduced into the earth via two current electrodes and the produced voltage is measured with other electrodes. Using the geometry of the electrodes, resistivity is calculated. Current Source Measure Current Measure Voltage Depth Below Ground Surface >> Current Flow Through Earth Voltage 11

12 Oklahoma Site: Electrical Resistivity Survey LESS RESISTIVE MORE RESISTIVE Background Survey Line West of Release Release Point 12

13 Oklahoma Site: Electrical Resistivity Survey CONDUCTIVE ZONE DUE TO PRODUCED WATER Source Area Survey Line Release Point 13

14 Oklahoma Site: Electrical Resistivity Survey CONDUCTIVE ZONE DUE TO PRODUCED WATER Source Area Survey Line Release Point 14

15 Oklahoma Site: Electrical Resistivity Survey East of Release Release Point 15

16 Oklahoma Site: Electrical Resistivity Survey East of Release Release Point 16

17 Oklahoma Site: Electrical Resistivity Survey East of Release Release Point 17

18 Oklahoma Site: Electrical Resistivity Survey East of Release (clean margin) Release Point 18

19 Resistivity Vs. Electromagnetics Electrical Resistivity Electromagnetics 19

20 Conductivity ms/cm EM and ERI Results Comparison Horizontal position (feet) CONDUCTIVE ZONE DUE TO PRODUCED WATER 20

21 Conductivity ms/cm EM and ERI Results Comparison Horizontal position (feet) 21

22 Oklahoma Site: 3D EVS Model (Environmental Visualization Systems)

23 Oklahoma Site: 3D EVS Model (Environmental Visualization Systems)

24 Oklahoma Site: 3D EVS Model (Environmental Visualization Systems)

25 Findings/Conclusions Successful non-invasive imaging of produced water extent. Vertical as well as lateral delineation. Based on the results of the ER survey, vertical impacts in the vicinity of the release area did not extend beneath the shallow, alluvial groundwater zone.. 25

26 Findings/Conclusions The use of surface geophysical methods eliminated the need for the installation of deep monitoring wells. To remediate impacted soils, approximately 48,500 tons of impacted soil were removed from the site.

27 Other Applications: ERI and Induced Polarization (IP) Surveys NAPL Mapping Aquifer/Lithology Mapping 3D Injectate/Air Sparge Imaging Brine Mapping Soil Boring into IP Anomaly Soil Core with Impacts at IP Anomaly Extent of Air Sparge Radius of Influence Using Non-Invasive Imaging BEFORE You Drill Saves Time and Money.

28 Imagine the result Imagine the result