flowback tech - moema€¦ · 500 ppm immediately dangerous to life or health (idlh) ca (potential...

Workers Evaluated

• Flowback Tech

– gauging flowback tanks

Workers Evaluated

• Flowback Leadman

– monitoring/operating separator

Location of worker shade tent

Workers Evaluated

• Production Watch

– gauging production tanks

Exposure Assessments: VOCs, Benzene

1. Full-shift and short-term industrial hygiene samples • Sorbent media and filters

• Personal breathing zone (PBZ), area air samples

2. Spot measurements • Real-time, direct reading instruments

– Hand-held PID,

– wearable PID,

– 4 gas monitors

– Dräger Chip Measurement System (benzene)

Occupational Exposure Limits*: Benzene

Exposure 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

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

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

Spot Measurements, Headspace of Tanks

• Flowback tank (no controls)

– VOCs: 10–2000 ppm

– Benzene : 0–>250 ppm

• Flowback tanks (with controls)

– 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

Area Spot Measurements

• Downwind of flowback tank

– VOCs: 0–200 ppm

– Benzene: 0–5 ppm

• Separator shed

– Benzene: 5 ppm (valve box open)

– Benzene: 0.0–0.2 ppm (valve box closed)

Location of worker shade tent

Full-shift PBZ Benzene Measurements (n=35) 1

TWA Range: Not Detected–0.65 ppm

Summary Stats (mean ± 1 standard deviation):

• Workers gauging tanks*

0.25 ppm ± 0.16 ppm (n = 17)

• Workers not gauging

0.04 ppm ± 0.03 ppm (n = 18)

* P < 0.05, Student’s t test

* P < 0.05, Student’s t test

1 Esswein, EJ, Snawder, J., King, B., Breitenstein, M. , Alexander-Scott, M., & Kiefer, M. (2014) Evaluation of Some Potential Chemical Exposure Risks During Flowback Operations in Unconventional Oil and Gas Extraction: Preliminary Results, Journal of Occupational and Environmental Hygiene, 11:10, D174-D184

0 0.05 0.1 0.15 0.2 0.25 0.3

Not gauging (n=18)

Gauging tanks (n=17)

PBZ average (mean) benzene concentrations

PBZ benzene (mean)

PPM

5 fold difference in personal air samples: workers gauging tanks vs. not gauging

NIOSH REL

5 fold difference in personal air samples: workers gauging tanks vs. not gauging

NIOSH REL ACGIH TLV

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

100

200

300

400

500

600

6:5

9:4

0

7:3

2:4

0

8:0

5:4

0

8:3

8:4

0

9:1

8:1

6

9:5

1:1

6

10

:24

:16

10

:57

:16

11

:32

:18

12

:05

:18

12

:38

:18

13

:11

:18

13

:44

:18

14

:17

:18

14

:50

:18

15

:23

:18

15

:56

:18

16

:29

:18

17

:04

:01

17

:37

:01 0

100

200

300

400

500

600

7:1

1:3

18

:17

:41

9:2

3:5

11

0:3

0:0

11

1:3

6:1

11

2:4

2:2

11

3:4

8:3

11

4:5

4:4

11

6:0

0:5

17

:05

:41

8:1

1:5

19

:18

:01

10

:24

:11

11

:30

:21

12

:36

:31

13

:42

:41

14

:48

:51

15

:55

:01

17

:01

:11

16

:32

:51

VOC ppm

Q. Why was the gauging worker’s peak and TWA exposures so high?

A. Worker did not consistently gauge standing atop the tank. Gauging from ladder reduces distance to source resulting in higher exposures.

149 ppm Benzene at 18 inches above hatch

1.2 ppm Benzene at 54 inches above hatch

TWA: time-weighted average

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

0

100

200

300

400

500

600

7:1

5:2

57

:49

:05

8:2

2:4

58

:56

:25

9:3

0:0

51

0:0

3:4

51

0:3

7:2

51

1:1

1:0

51

1:4

4:4

51

2:1

8:2

51

2:5

2:0

51

3:2

5:4

51

3:5

9:2

51

4:3

3:0

51

5:0

6:4

51

5:4

0:2

51

6:1

4:0

51

6:4

7:4

51

7:2

1:2

5

0

100

200

300

400

500

600

7:1

7:3

4

7:5

5:5

4

8:3

4:1

4

9:1

2:3

4

9:5

0:5

4

10

:29

:14

11

:07

:34

11

:45

:54

12

:24

:14

13

:02

:34

13

:40

:54

14

:19

:14

14

:57

:34

15

:35

:54

16

:14

:14

16

:52

:34

17

:30

:54

18

:09

:14

VOC ppm

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

A. Worker stood to sample; higher PBZ height above hatches. However, he spent the entire shift on top of the tank in hydrocarbon plume.

Open Hatch

worker’s bucket

bucket

High contrast FLIR image

Example 3: Patterns of Exposure during Gauging (temporal and spatial)

• Worker gauging production tanks – Workers usually gauged hourly (12 times/shift)

– PBZ Peak VOC = 465 ppm

– PBZ Benzene: Short term = 2 ppm; TWA = 0.14 ppm

– Area Benzene upwind of hatch = 5 ppm

– Area Benzene downwind of hatch = 40 ppm

0

100

200

300

400

500

600

12

:20

12

:21

12

:21

12

:22

12

:22

12

:23

12

:23

12

:24

12

:24

12

:25

12

:25

12

:26

12

:26

12

:27

12

:27

12

:28

12

:28

12

:29

12

:29

12

:30

12

:30

12

:31

12

:31

12

:32

12

:32

12

:33

12

:33

12

:34

12

:34

12

:35

12

:35

VOC

Q: Why was the gauging worker’s peak exposures so high?

A: Headspace pressure and VOCs build up in tank before dumping to the combustor. Risks for exposures: opening hatches to gauge tank.

VOC plume emitted after hatch was opened

Other chemicals -2013 flowback sites

• Alcohols - ND –trace concentration

• Aldehydes ND –trace concentration

• Toluene, xylenes, ethyl benzene, naphthalene <<OELs

• Silica <<OELs

• Biological exposure monitoring (benzene) < ACGIH BEI

ND – not detected Trace – between limit of detection and limit of quantitation OELs – occupational exposure limits

Diesel particulate

Photo: courtesy of Jeff Swensen, NY Times

Photo: courtesy of Jeff Swenson, for the NY Times

DPM aerosol

Early morning Daytime early a.m. Real-Time Diesel Particulate Monitor

Diesel Particulate (DPM)

• Neither OSHA nor NIOSH have occupational exposure criteria for DPM as elemental carbon (EC).

• California Dept. of Health Services: OEL of 20 µg/m3 DPM (as EC) as a time-weighted average (TWA).

• Value based on an EPA human health risk assessment for exposures for DPM referenced as EC.

Exposure Risks: DPM

Site X • 3/13 (23%) > 20 µg/m3

• 4 samples (2 PBZ, 2 area) > 40 µg/m3

• Range: ND to 90 µg/m3

Diesel Particulate Exposure • Exposures appear to be episodic.

– Ultrafine particulates increase during heavy pumping; i.e., during hydraulic fracturing operations.

– Ambient wind, worker location in relation to source are related to DPM exposure risk.

• Traffic and idling equipment do not appear to be major contributors to exposures.

Hydrogen Sulfide (H2S)

• PEL: 20 ppm (C) 50 ppm (1 x per 8 hr. shift)

• NIOSH: 10 ppm (C) 100 ppm IDLH

• TLV: 1 ppm, 5 ppm (STEL)

Biocides added to fracturing fluids to reduce bacteria than can produce H2S

Biocides •

Summer 2013 Glutaraldehyde samples 9 samples 8 = not detected 1 PBZ =trace concentration

Exposures to Chemicals in Drilling Muds?

• Volatile organic compounds?

• Barite?

• Dermal exposures?

Oil Mists?

Shale shaker on drilling rig

U, Th, Ra, Rn Potential sources/operations:

• Drill cuttings

• Blooie line emissions

• Pipe scale

• Reserve pit/tank sludges

• Flowback water

• Pipe inspection operations

TENORM?

Photo: NIOSH Western States Office

Risks Unknown: SIMOPS, potential for mixed exposures?

Silica, DPM

Benzene, TENORM

DPM, PAH’s. NOx, Ozone

Pb, H2S Oil mists, DPM

Biocides

What do we really know about upstream health and safety risks?

• Motor vehicle crashes #1 cause of fatalities • Struck by/caught between, falls from heights, fires + explosions

• Respirable crystalline silica: occupational health hazard for completions crews

• Exposures can exceed the MUC for half mask and FF respirators, numerous point sources of dust generation

• Benzene: exposure risks > NIOSH REL during tank gauging -preliminary study: more samples, broader study needed

• Diesel particulate: a contributing inhalation health risk • Lead: drilling, pipe dope, take home hazards

• Likely controlled through hazards awareness/product susbstitution

• TENORM: possible hazard? • Mixed exposures: (e.g., gases + particulates, dermal) • More IH exposure assessment research is needed

We know: health and safety risks

Questions?

Eric Esswein, NIOSH eje1@cdc.gov 303 236-5946