Function and Working principle of Blow out Proventer.

Blow out Proventer (BOP).

 The Deep water Horizon blowout preventer

commonly known as a BOP stood nearly

six stories tall weighing over 300 tonsK

and was designed to hold well pressures

up to 15,000 psi the horizon BOP stat

was manufactured by Cameron in 2001 and

equipped with two annular Boreas upper

and lower and 5r m areas consisting of

a blind shear Ram a casing shear Ram two

variable bore rams and a test ram at the

bottom which was requested by BP to

expedite pressure testing of the BOP

the blind shear Ram variable bore Rams

and test Ram were fitted with Cameron

standard Ram bonnets containing the

actuate ins and st locks designed to

hold the ram preventers closed in the

event of a loss of pressure 

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five and a half inch diameter drill pipe

passed through the BOP on the day of

the incident each joint was roughly 46

feet long with 18 inch long threaded

connections or tool joints on each end

of the pipe a tool joint was

intentionally positioned in the BOP to

properly space the tubular section

through the ram BOP during the well

abandonment procedures as well pressure

pushed the drill pipe upward in the BOP

the drill pipe bowed at roughly 943 p.m.

local time

the crew of the deep water horizon

activated the upper annular a steel

reinforced rubber donuts device that

squeezes tied around any pipe located in

the BOP the annular closed around the

tool joint and drill pipe the increasing

fluid velocity eroded the rubber annular

closing element the steel drill pipe and

the steel tool joint preventing the

annular BOP from sealing tight a

close-up of the actual tool joint shows

the rapid and complete degradation

caused by the Swift movement of fluids

acting like a water jet cutting device

slicing through the metal and creating

pathways for continued upward flow of

fluid in the space between the steel

pipe and rubber annular closing element

at approximately nine forty six pm

roughly three minutes before the first

explosion the riser evacuated onto the

drill floor discharging a combination of

expanding gas drilling mud and sea water

onto the decks seconds later the drill

crew activated both the upper and lower

variable bore Rams the variable boy Rams

are engineered to seal around variable

diameters of drill pipe from three and a

half inches to six and 5/8 inches in

diameter

with the activation of the variable bore

pipe Rams the will flow was secured but

pressure continue to build within the

drill pipe itself and hydrocarbons and

gas that had already entered the riser

above the blowout preventer continued to

expand and exhaust to the rig shortly

after the variable bore Rams were

engaged gas from the well dispersed and

mixed with air the gas mixture was

ingested by the running engines causing

them to over speed and shut down power

on the rig was then lost resulting in a

blackout and loss of dynamic positioning

capability the first explosion 

on board

the Deep water Horizon occurred just

seconds later as pressure increased the

drill pipe ruptured where the steel had

been severely washed away and eroded

well bore fluids again flowed upward in

the riser to the surface without power

the rig was no longer able to remain in

position the rig drifted off location

stretching the drill pipe held in the BO

P

within minutes the drill pipe was

pulled apart nearly at the same point

above the tool joint where the initial

rupture had occurred close examination

of the actual severed drill pipe

recovered from the Deep water Horizon BO

P after the incident shows the effect

that high pressure flow had in eroding

the pipe as well as the location where

the pipe was pulled apart the horizon BO

P was equipped with a built in battery

powered automatic mode function device

commonly known as the AMF the purpose of

the AMF is to activate the blind shear

Rams under a scenario in which hydraulic

pressure and electric power are lost

from the surface such as a riser failure

or other event where the BOP cannot be

operated from the drilling rig the

exact time when the AMF activated either

before or after the drill pipe was

pulled apart is unknown however the AMF

did what it was designed to do actuate

the Shearer Rams then set the st locks

forensic analysis indicates that the

shear Rams were unable to move all the

bowed drill pipe into the shearing

blades part of the bow drill pipe was

held for a period by the flat outer

faces of the RAM blocks when released

the top section of the pipe was

propelled upward and was later found

resting on the top of the upper annular

meanwhile well bore fluids continued

flowing at high pressure through the

pipe the rubber seals on each side of

the shear Rams were washed out allowing

the well to continue to flow around the

sides of the blind shear Rams in this

close-up view of the shear Ram we see

how the high velocity fluids from the

severed drill pipe flowed around the

round blocks eroding the rubber side

Packers and cutting into the body of the 

BO

P

even as the core mechanisms of the

BOP closed as designed as the close-up

moves across the face of the RAM

significant erosion can be seen on both

sides of the RAM block at this time the

drill floor was on fire the drill line

was weakened and the traveling block best

described as an arrangement of pulleys

through which the drill pipe is raised

and lowered fell down through the

derrick and onto the rig floor

subsequently the drill pipe dropped and

came to rest on top of the upper annular

BOP roughly 36 hours later the

Deep water Horizon sank into the Gulf of

Mexico bending the riser on its way to

the sea floor and kinking it just above

the BOP.