Occurrence of BTEX from Oil- and Gas-Related Incidents in Groundwater above the Denver-Julesburg Basin

Transcription

1 Occurrence of BTEX from Oil- and Gas-Related Incidents in Groundwater above the Denver-Julesburg Basin Katherine J. Armstrong, Jessica D. Rogers, Troy L. Burke, and Joseph N. Ryan University of Colorado, Boulder

2 Objectives Understanding spills and releases Frequency Groundwater contamination potential Causes Facility types Materials released Future exposure assessments of organic contaminants in groundwater

3 BTEX in groundwater What are the BTEX compounds? Present in: hydraulic fracturing fluids flowback and produced waters petroleum products Frequently tested in Colorado Oil and Gas Conservation Commission (COGCC) database Proxy for other organic compounds of concern

4 Colorado Oil and Gas Information System (COGIS) Spill files Laboratory data, consultant reports

5 Colorado Oil and Gas Information System (COGIS) Remediation files Laboratory data, consultant reports

6 Incidents considered 2010 and 2012 (planned: ) Incident date > Form 19 submit date > Form 27 submit date Township-range box COGCC GIS Online

7 Identifying potential groundwater impact Operator-reported field Spill reports Remediation reports Manual review of spill and remediation files with identified/possible groundwater impact

8 Number of distinct incidents Year All incidents* Groundwater impact Total *Predicted

9 Facility types (groundwater impact) flow line 27 incidents tank battery 153 incidents tank battery flow line gas compressor station gathering line liquid containment pond gas pipeline pit well pad unknown

10 Incident causes (groundwater impact) 15 historical (equipment failure) historical (undefined) equipment failure 112 incidents equipment failure historical (undefined) historical (equipment failure) vandalism human error unknown line repair

11 Materials released (groundwater impact) produced oil water incidents incidents condensate 86 incidents produced water condensate oil unknown natural gas brine calcium-chloride enriched water

12 Rates of spills/releases (producing wells) Year Producing wells All incidents* Groundwater impact Groundwater impact (BTEX) , % 0.57% 0.52% , % 0.41% 0.35% *Predicted

13 Rates of spills/releases (producing wells) Gross et al. (2013) Surface spills affecting groundwater associated with <0.5% of active wells (July 1, 2010 July 1, 2011)

14 Overall incidents per million barrels produced 49 th US GWPC Rock Mechanics Underground Geomechanics Injection Conference Symposium February June 23-25, 28 July , 2015 Overall incidents per million barrels produced Rates of spills/releases (production volumes) OIL PRODUCED WATER million bbl 41 million bbl 41 million bbl 60 million bbl

15 Challenges and uncertainties Manual file review Locating basic information Lab data availability Actual spill/remediation overlap Historical releases

16 Conclusions Characteristics of groundwater-impacting spills Facilities: tank batteries, flow lines Causes: equipment failure, historical releases Materials: produced water, condensate, oil Frequency, extent of groundwater impacts All spills: ~1.2% of number of producing wells Groundwater impact: ~40% of spills BTEX groundwater impact: ~90% of groundwaterimpacting spills