exposure hazards in oil and gas extraction workers ......flowback and production testing...

Exposure Hazards in Oil and GasExtraction Workers:

Flowback and Production Testing(Completions Operations)

Bradley King, PhD, MPH, CIHNIOSH Western States Office

WestONSeptember 12, 2014

Golden, CO

Disclaimer

The findings and conclusions in this presentationare those of the author(s) and do not necessarilyrepresent the views of the National Institute forOccupational Safety and Health.

NIOSH Field Effort to AssessChemical Exposure Risks toOil and Gas Workers

www.cdc.gov/niosh/docs/2010-130/

What is Flowback?

Process fluids from wellbore returnto the surface and are collectedafter hydraulic fracturing iscompleted.

Returned fluids can contain volatilehydrocarbons from the formationand treatment chemicalsused during hydraulic fracturing.

Risks for exposures: measuringflow, gauging tanks, working aroundtanks and process fluids

http://carpinteriavalleyassociation.org/2012/09/frack-attack-new/

Field Visits: Spring/Summer 2013

•Six sites in Colorado and Wyoming– Fields: Piceance, Jonah, DJ Basin

– Worker activities: Flowback, Production watch, Watertransport, Lease operations

1. Identify processes/activities that may poseexposure risks

2. Identify sources of exposures

3. Assess exposures

Workers Evaluated

•Flowback Tech

–gauging/strappingflowback tanks

Workers Evaluated

•Flowback Leadman

–monitoring/operating separator

Workers Evaluated

•Production Watch

–gaugingproduction tanks

Industrial Hygiene Methods

1. Full-shift and short-term samples for VOCs(e.g., benzene), PAHs, alcohols,glutaraldehyde, and silica/respirable dust

•Sorbent media and filters

•Personal breathing zone (PBZ) and area air samples



1. Sorbent media and filters

2. Personal breathing zone (PBZ) and area air samples

2. Spot measurements for VOCs and benzene1. Real-time, direct reading instruments

2. PBZ and area air samples



1. Sorbent media and filters

2. Personal breathing zone (PBZ) and area air samples

2. Spot measurements for VOCs and benzene1. Real-time, direct reading instruments

2. PBZ and area air samples

3. Lower explosive limits (LEL) monitoring

Occupational Exposure Limits*: BenzeneExposure Limit Limit Values

Occupational Safety and Health Administration (OSHA)

Permissible Exposure Limit (PEL) - General Industry

1 part per million (ppm) time-weighted

average (TWA)

5 ppm short-term exposure limit (STEL)

OSHA PEL –

Sectors Excluded from General Industry

10 ppm TWA

25 ppm Ceiling

50 ppm Maximum peak above ceiling (10

minutes)

National Institute for Occupational Safety and Health (NIOSH)

Recommended Exposure Limit (REL)

0.1 ppm TWA

1 ppm STEL

500 ppm immediately dangerous to life or

health (IDLH)

Ca (potential occupational carcinogen); Skin

American Conference of Governmental Industrial Hygienists (ACGIH)

Threshold Limit Value (TLV) (2013)

0.5 ppm TWA

2.5 ppm STEL

A1 (confirmed human carcinogen); Skin; BEI

(Biological Exposure Index)

*based on an 8-hour TWA, 40 hour work week

*based on an 8-hour TWA, 40 hour work week

Spot Measurement, Headspace of Tanks

• Flowback tank (no controls)–VOCs: 10–2000 ppm

–Benzene : 0–>250 ppm

• Flowback tanks (with controls)–Reduced Emissions Completions

(REC)

–VOCs: 10–400 ppm

–Benzene: 0–30 ppm

Spot Measurements, Headspace of Tanks

• Production tanks

–VOCs: 10–>2000 ppm

–Benzene: 0–>300 ppm

• Water tanks

–VOCs: 10–200 ppm

–Benzene: 0–>40 ppm

Full-shift Personal Breathing ZoneBenzene Measurements

TWA Range: Not Detected–0.65 ppm

* P < 0.05, Student’s t test

• p< 0.05 (Student’s t test),for gaugers vs. non-gaugers

Worker Benzene Biomonitoring

•s-PMA Range: 0–20.9 µg creatinine

•Summary stats:

–Average for workers gauging tanks:

6.1 ± 5.3 µg creatinine (n=17)

–Average for workers not gauging tanks:

2.5 ± 3.9 µg creatinine (n=18)

Example 1: Patterns of Exposure during Gauging(temporal and spatial)

Worker gauging once per hour vs. Worker not gauging– Peak VOC = 537 ppm Peak VOC = 23.5 ppm

– TWA VOC = 5.89 ppm TWA VOC = 0.203 ppm

– TWA Benzene = 0.23 ppm TWA Benzene = 0.01 ppm

0

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VOC ppm

Q. Why were the gauging worker’s peak exposures so high?

A. This worker did not consistently gauge standing on top of thetank. Gauging from ladder reduces distance to source resulting inhigher exposures.

149 ppm Benzene at 18 inchesabove hatch

1.2 ppm Benzene at54 inches above hatch

Example 2: Patterns of Exposure during Gauging(temporal and spatial)

Worker gauging 2x each hour vs. Worker not gauging– Peak VOC = 523 ppm Peak VOC = 42.9 ppm

– TWA VOC = 20.2 ppm TWA VOC = 1.87 ppm

– TWA Benzene = 0.45 ppm TWA Benzene = 0.05 ppm

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VOC ppm

Q. Why were the gauging worker’s exposures so high?

A. Worker was very careful to sample at his full height abovehatches. However, he spent the entire shift on top of the tank inhydrocarbon plume.

Open Hatch

Worker’s Bucket

bucket

Open Hatch

Example 4: Patterns of Exposure Downwind of Tanks(temporal and spatial)

Immediately downwind of flowback tank (10 meters)– Very early stage of flowback

– PBZ Peak VOC = 220 ppm

– PBZ TWA VOC = 46.8 ppm

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VOC ppm

Q. Why were these exposures elevated?

A. Sampling location was less than 10 meters from tank, while plugs

were being drilled. Potential for very high release of hydrocarbons.

– Area Peak VOC = 200 ppm

– Area TWA VOC = 17.1 ppm

– Area TWA Benzene = 1.1 ppm

Hot fluid level

VOCs

Other Compounds Monitored• Glutaraldehyde:• Glutaraldehyde:

–All PBZ and area samples below limit of detection(LOD), except for one

–one PBZ sample returned a trace concentration

• Propargyl Alcohol:–All area samples below LOD, except for one–one area sample returned result of 0.0043 ppm

• Methanol:–All area samples below LOD

Other Compounds Monitored

•PAHs:

–Napthalene detected in multiple samples at partsper billion (ppb) range

•Silica and respirable dust:

–All PBZ samples below NIOSH, OSHA, ACGIH OELs,except for one

•This one sample was invalid due to accidentalcontamination

Flammable/Explosive Hazards

•Direct reading instruments showed manyinstances of short term excursions measuringas high as 40% of the Lower Explosive Limit(LEL)

–especially while drilling plugs and during snubbing

–measured near areas of flowback tanks,separators, and tank batteries

Conclusions

•Risks for VOC, benzene exposures:

–spatial and temporal variables

–intermittent, task-based

•Gauging tanks:

–highest risk for exposures, contributes to highestTWAs

–only few minutes, repeated throughout day

Conclusions (cont’d.)

•Potential for exposures:

–dependent on proximity to sources

•pad perimeter monitoring, very low levels of total VOCs

•Potential for exposure varies:

–formation, basin

–“Age” of well, notable factor for exposures


•Controls are available

–Reduced Emissions Completions (i.e., ‘greencompletions’): appears to reduce potential forexposures through containment

Portable REC equipment Source: https://www.globalmethane.org/expo-docs/india10/postexpo/oil_robinson.pdf

Portable REC equipment Source: https://www.globalmethane.org/expo-docs/india10/postexpo/oil_robinson.pdf


•Potential for exposures to other analytesmeasured during flowback appeared to be low

•Flammable/explosive hazards can exist due tothe presence of combustible gas peaksdetected

Request for Assistance

Additional field research required•Additional field research required

•Requesting additional industry partners toassist in further evaluating sites, locations, andactivities

•These results are preliminary

•Communication of initial research results:NIOSH Science Blog, journal article,conference presentations

Questions?

Alice Hamilton, M.D.Mother of U.S. Occupational Medicine1869–1970

Email:[email protected]

exposure hazards in oil and gas extraction workers ......flowback and production testing...

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