Testing Layout

SWT LAYOUT &

SAFETY

FTC-SWT
December 4, 2021
 Testing Layout

Lecture Objectives,

- By the end of this lecture, YOU should be able to:

•describe a typical OFF-shore & ON-shore Testing Layout

•identify all the classified zones in a well

•understand the dangers of H2S, Heat radiation, Noise, Electricity

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 Testing Layout
Typical Offshore
SWT Layout

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 Testing Layout

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 Testing Layout
THE LAYOUT DIAGRAM:
• defines which pieces of surface testing equipment have to
be used.
• identifies where the equipment is located (zones and
recommended distances)
• illustrates the sequence in which the equipment is
connected.
• shows the general piping with vent lines layout and ESD,
air lines.

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 Testing Layout
THE LAYOUT VARIES ACCORDING TO:
• Location
- land or offshore operation
• Well conditions
- flow rate and pressure
- effluent properties (oil properties and hydrate
formation)
- sand production
- presence of corrosive fluids (H2S, CO2, acid)
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Testing Overview Testing Layout
ON shore Remark (only for FTC exercices):
CM at rig floor= 1 x Coflexip
SWT Layout
hose

Oil pit or Gas pit or

Burners Vertical gas flare
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 Testing Layout
ON shore Layout
• Dominant wind direction must be identified
1. Oil and Gas PITS used: both must be located about 300
feet from Wellhead & Testing area and also be separated
from 300 feet.
2. Oil burners used (two): both must be located about 150
feet from Wellhead & Testing area and also opposites.
3. Vertical Gas flare used (one): must be located about 300
feet from Wellhead & Testing area.
The used of burners avoid pollution (black smoke).

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 Testing Layout
ON shore Layout
1. Oil and Gas PITS used: both must be located about 300
feet from Wellhead & Testing area and also be separated
from 300 feet.
2. Oil burners used (two): both must be located about 150 feet
from Wellhead & Testing area and also opposites.
3. Vertical Gas flare used (one): must be located about 300
feet from Wellhead & Testing area.
Today, burners are more frequently
used than burning pits on land, for both
SAFETY & ENVIRONMENTAL
reasons.
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 Testing Layout
ON shore Layout
Lines to Oil & Gas PITS or Burners / Flare:
• These lines must be secured and/or anchored to the ground
to prevent whipping
• Generally old tubings are used, supplied by the Client
- X-over are needed between tubings & Slb piping

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Testing Layout Testing Layout
OFF shore
SWT
Layout

Remark (only for FTC

exercices):
CM not at rig floor= 2 x
Coflex

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 Testing Layout
OFF shore Layout
• Some offshore rigs have permanent piping (rig’s property) to
facilitate the connection between the different pieces of
equipment.
• Generally they are available between the Rig Floor and the
SWT area and between the SWT area and the booms area.
• Permanent piping, may be used if it complies with the POM.

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 Testing Layout
Layout General
• Placing the Choke Manifold on the rig floor, it:
-limits the length of high pressure piping
-reduces the pressure drop between FH & CM
-gives more accurate WHP & WHT
• The piping between FH & CM is call “Flowline”
• The “flowline” must be flexible on all floaters rigs, and it is
recommended on all other fixed rigs.

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 Testing Layout
Layout General
• Offshore, two burners mounted on booms, one on each side of
the rig. One burner or the other is used, depending on the wind
direction.
• Burners require compressed air to properly burn the oil and
propane is necessary to supply the pilot lights for the burners.
• A water pump is used to inject water into the oil flame at the
burner (old generation), and to create a water screen behind the
burners, which reduces heat radiation.
• Whenever H2S presence is expected, gas shall be vented to
flare.
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 Testing Layout
Layout General
• Correct piping size prevents:
- very high fluid velocities
- large pressure losses
- over pressurization of the equipment

• In some tests, the effluent may be injected into a pipeline

(production line).

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 Testing Layout
SAFETY, is a major factor in designing and conducting a well
test.
• Equipment layout and spacing must be in accordance with
classified zones.
• All pieces of surface testing equipment must be grounded.
• Electrical connections (such as transfer pumps or laboratory
cabins) must be safe and approved according to industry
standards.
• Piping (flowlines and all vent lines) must be anchored.
• Piping must be color coded to identify the WP of the pipe.
FTC-SWT• The dominant wind direction must be identified to properly
December 4, 2021
orient equipment that vents or burns gas.
 Testing Layout
Classified zones
• A well site is classified into zones or areas based upon the
probability that flammable gases or vapors may be present around
a specific piece of equipment.
• Schlumberger recommends no overlap of classified zones.
• Zone restrictions do not dictate the placement of all well test
equipment. For example, the ESD system and Oil & Gas
manifolds, usually place in zone 2, are not restricted to that
specific zone.

For further information on the zone classifications, see API – 64B

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Classified zones
• ZONE 0
- area where any flammable or explosive substances are
continuously present.

The borehole
The well below the wellhead

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 Testing Layout
Classified zones
• ZONE 1
- area where any flammable or explosive substances are
processed, handled or stored.
The gauge tank (gas release from vent in the immediate
vicinity).
The choke manifold (sampling causes some gas release).
The flowhead (due to tools introduction during a well
test), when
tools introduction are not being made, the flowhead is
zone 2.
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Most electric-driven transfer pumps.

 Testing Layout
Classified zones
• ZONE 2
- area where any flammable or explosive substances are
processed and stored under controlled conditions.
The separator (in case of a leak).
The indirect-fired heater (uses a naked flame).
The steam exchanger (can reach high temperatures).
Piping is defined as a Zone 2 area.
Diesel-driven transfer pumps (if equipped with automatic
shut-down system, sparks arrestors, inertia or special electric
starters).
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 Testing Layout
Classified zones
• CLEAN ZONE (also nonhazardous or safe areas)
- NO flammable or explosive substances are processed,
handled or stored.
The living quarters (of an offshore drilling rig)

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 Testing Layout
Onshore

Flowhead: 45ft (15m)

around

Indirect heater: 30ft Gauge tank: 45ft

(10m) (15m)

Zone 1 Zone
Separator: 30ft (10m) 2
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 Testing Layout
Offshore

Flowhead: 30ft (10m)

around

Heat exchanger: 30ft

Surge tank: 45ft (15m)
(10m)

Zone 1 Zone
2
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 Testing Layout
Onshore
Recommended
distances

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 Testing Layout
Offshore
Recommended distances

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Safety standards for equipment layout

•The top area around the separator rupture disc pipe is

classified as Zone 1, with 15ft (5m) around.

•The area within 15 ft above the roof of the gauge tank is

classified as Zone 1.

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 Testing Layout
H2S service requirements and safety
Hydrogen sulfide (H2S) is dangerous because it has a wide
explosive range and is highly toxic.
• H2S Properties
Properties Description
Color None
Odor extremely offensive, “rotten eggs”
Density 1.189, heavier than air (1.000)
Explosive limits 4.3% to 46%
Ignition temperature 500degF (260degC)
Water solubility four volumes of gas in one volume of water at 32degF
(0degC)
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H2S service requirements and safety
• H2S Toxicity
Concentration Toxic Effects
1 ppm (0.0001%) H2S can be smelled, >1ppm: leave the area or use PPE (SBCA)

10 ppm (0.001%) Maximum 8 hours work period allowed

>100 ppm (0.01%) Odor “disappears”, eyes and throat burn, loss of consciousness,
permanent brain damage or death.

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H2S service requirements and safety (Operation guidance)
- Mandatory prejob safety meeting for all personnel
involved.
- Constant supervision of the job & use a minimum of 2
experienced, H2S certified engineers or technicians.
- Do not allow H2S to escape into the atmosphere in any
place where it can accumulate.
- Monitor the wind direction constantly.
- Wear breathing apparatus when: surface sampling,
measuring gas SG, changing Daniel orifices and chokes,
bleeding off pressure, walking on burner boom.
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- Operate instruments with compressed air
 Testing Layout
H2S service requirements and safety
• Equipment safety
In addition to its adverse health effects, H2S is highly corrosive to
metals
- Equipment not positively identified as H2S service must
be assumed to be not rated for H2S service.
- Welding performed outside a qualified shop on H2S
equipment invalidates the H2S rating.
- Piping with threaded connections is not rated for H2S
service.
FTC-SWT - Use only a surge tank offshore; never use an atmospheric
December 4, 2021
gauge tank offshore.
 Testing Layout
Heat radiation
• Problems associated with heat radiation arise primarily during
burning operations and are a serious problem for both personnel &
equipment.
Quantity Description
330 Btu/hr/ft2 Greatest solar radiated heat at soil level
440 Btu/hr/ft2 Upper limit for harmless exposure of bare human skin
1500 Btu/hr/ft2 API RP 521 recommended upper limit for an oilfield worker wearing
work
clothes and intermittently sheltered or sprayed with water.

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Heat radiation
• Easy solutions for managing excess heat are to
- inject water into the flame
- install additional water screens behind the burners
- install water ramps alogside the hull where excess heat
can be radiated
- use longer booms (85 ft or 26m)

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Noise
Ear protection is critical for all personnel exposed to noise during
well test operations.
• ISO Noise Exposure Recommendations
Noise Level (dBA) Permissible Exposure
Examples:
90 8hr/D
• a sep. flowing 4000bopd with a GOR
95 4hr/D
of 300, generates a noise level of 62
100 2hr/D dBA.
105 1hr/D •From 100ft, a 6” gas line with
110 1/2hr/D 10mmscfd, generates a noise level of
96 dBA., and with 35 mmscfd the noise
115 10mn/D
level is 107 dBA.
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Electrical safety
Electrical equipment located in hazardous areas must meet
protection standards
The most commonly used means of protection are:
• intrinsic safety
• explosion proof

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The
END

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