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