The document summarizes the timeline and key events of the Deepwater Horizon oil spill that occurred in 2010 in the Gulf of Mexico. It describes 10 events that occurred, including issues with the cementing job, temporary abandonment plan, failure to properly interpret a pressure test, diversion of hydrocarbons to the mud-gas separator, and failure of the blowout preventer. It then discusses environmental impacts to ecosystems, sea turtles, seabirds, and marine mammals. Finally, it lists 8 preventative measures that should have been adopted, such as using more centralizers during the cementing process and installing additional sensors along the riser.

1. DEEPWATER HORIZON
By
AKSHAY GUPTA, KUNAL SINGHAL & SAURBH SENGAR

2. THE TIMELINE

3. CHRONOLOGICAL SEQUENCE OF EVENTS
OCCURRED AND THEIR CAUSES
1. Centralizers

4. CHRONOLOGICAL SEQUENCE OF EVENTS
OCCURRED AND THEIR CAUSES
2. Cementing Job:
 ‘Nitrogen foam cement’ was used to lighten the resulting slurry
from approximately 16.7 ppg to 14.5 ppg—thereby reducing the
pressure the cement would exert on the fragile formation.
 Third party test results suggest that the foam cement slurry used for the
Macondo well was likely unstable, resulting in nitrogen breakout.
3. Float Collar and Shoe Track barrier:
 Flow rate of 1 bpm was used and float collar was converted at 3,142
psi inconsistent with the manufacture guidelines of using 5-8 bpm and
500-700 psi. No perfect evidence exist that float collar was converted.
 Shoe track failure could be its contamination by nitrogen
breakdown from the nitrified foam cement.

7. 4. Improper Bottoms- Up circulation
5. Cement bond log test: A test that is required to check the stability
of cement plug was not conducted. The Schlumberger team was
sent back without verifying the integrity of cement plug.

8. 6. Temporary Abandonment Plan
The major flaws in their plan was –
a) 3,300 feet of mud below the mud line was replaced with seawater.
It placed more stress on the cement job at the bottom of the well than
necessary.
b) Used an unusually large amount (425 bbl) of 16 ppg spacer to complete
the displacement.

9. 7. Wrong
interpretation of
Negative
Pressure Test
Results
 For a successful
negative pressure test,
the pressure in
drillpipe and kill line
must be same.

10. 8. Diversion to mud-gas separator
Diversion of hydrocarbons coming through the riser to the mud gas
separator quickly overwhelmed the MSG and failed to control the
hydrocarbons exiting the riser.

11. 9. Failure of BOP
 High pressure
hydrocarbon
degraded the
elastomer in
annular preventer.
 Buckling of pipe
and failure of BSR
to cut the drillpipe.
 Failure of AMF
dead man

12. 10. Failure of fire and gas system
The fire and alarm system
did not prevent the gas from
ignition source and caused
explosion.
 Gas dispersed beyond
electrically classified
areas.
 Gas ingress into engine
rooms via main deck air
intakes.
 The on-line engines were
one potential source of
ignition.

14. 1. Impact to the deep eco-system:
 Affected the coral communities
including extremely vulnerable and
slow to recover corals.
 Severe reduction in abundance and
diversity of bottom-dwelling (or
benthic) organisms.
2. Impact to sea turtles:
 More than 1,000 sea turtles were found
dead following the oil spill.
3. Impacts to Seabirds
 32% of the northern Gulf population of
laughing gull was killed along with 13%
of the royal tern population, 8 percent
of the northern gannet, and 12 percent
of the brown pelican population.

15. 4. Impacts to marine mammals:
 Disaster is acknowledged as the likely
cause of a unusual mortality event (UME-
defined as a stranding that is unexpected;
involves a significant die-off of any marine
mammal population) for dolphins and
whales in the northern Gulf of Mexico.
 Elevated concentrations of genotoxic
metals (such as chromium and nickel)
are found in skin tissues of Gulf
whales which causes genetic mutations
and cancer.
 The chemical dispersants used during the
oil spill, killed cells and damaged cell
DNA of sperm whale skin cells, leading
to sub lethal but perhaps long-term
harmful effects to whales.

16. More than 60 different species were likely to have been in
the spill region. Of these species, 40 are endemic, or found
only in the Gulf of Mexico.
A number of sub-lethal impacts of oil exposure have been
found in many species, including:
1. Disrupted growth, development, and reproduction
2. Tissue damage
3. Altered cardiac development and function
4. Disrupted immune system
5. Biochemical and cellular alterations
6. Changes in swimming ability

17. 4. Impacts to marine and estuarine habitats
 600 miles of sand beach habitat was oiled, and at least 400 miles of
oiled beaches also experienced some level of impairment due to
response activities.
 Marsh and mangrove habitats that were oiled experienced loss of
vegetative cover and condition.

18. PREVENTIVE MEASURES THAT SHOULD HAVE BEEN
ADOPTED
1. Liner with Tieback vs. Long String Design

19. PREVENTIVE MEASURES THAT SHOULD HAVE BEEN
ADOPTED (CONTD.)
2. The second alternative would have been having twenty-one centralizers that
were recommended, instead the six that BP used. Thus, preventing the
issues of gas flow and subsequent cement channelling.
3. As mentioned in the causes, the steps following the improper float collar
conversion aggravated the risks of the blowout. So, if the manufacturing
guidelines had been followed , then the risks would have been minimized.
4. Instead of using a single set of shear rams if 2 set of shear rams can be used
in a BOP placed perpendicular to each other at certain heights then buckling
cannot fail the BOP. Initially only the Lower BOP is activated but if the
problem persists seconds BOP is activated which will finally seal the pipe.
5. There were conflicting goals in the selection of BOP elastomers, specifically
to be flexible at low temperatures, but not extrude out at high temperature.
Elastomers become more fluid with increasing temperature, so it should be
recognized that sustained high flow may ultimately cause wellhead
temperature to exceed elastomer capability and lead to failure.

20. PREVENTIVE MEASURES THAT SHOULD HAVE BEEN
ADOPTED (CONTD.)
6. The instrumentation and displays used for well monitoring must be improved.
There is a need to develop more sophisticated, automated alarms and
algorithms which can be built into the display system to alert the driller and
mud-logger when anomalies arise. i.e for the kick detection.
7. Automated diversion i.e; the proper channeling of flow through riser could have
been done so as to reduce the direct pressure. With this, pressure in the main
stream can be reduced to a finite extent, thus giving more time to combat
the blowout.
8. Also, we propose to design an alarm whose sensors will be connected to
riser itself at some specific distance like if our riser is of 1000ft then we
will install it at every 250ft so that even any sensor fails then we will be
having a backup option. These sensors will be hydraulically operated as
it will be designed to get activated in case riser encounter a pressure
greater than a certain limit leading to this strengthening the safety
regulations even if hydrocarbons enter the riser before activating the
BOP’S which happened at Deepwater horizon

21. THANK YOU