That's a very small bop up there^ ... what we're talking about is taller then your house, and weighs around 450tonnes. 450,000 kg's!
Yeah acoustic triggers are what you're talking about, but they're fairly unreliable in my oppinion, and those of many others. The shears never sheared because the 9" casing from downhole was ejected up through the bop by the force of the blowout, they're not designed to cut 9" casing. I cannot emphasize the pressures and dynamic loads here and the damage it could of done to the intervals of the bop- now bops are fucking bombproof so it must of been crazy crazy forces (which I know it was...) External hydrostatic pressure down there is like putting a family car on a postage stamp. Imagine how many postage stamps cover your body? Ok, so NO engineers did not forget about temperatures!! This isn't our first rodeo in deep water, there is also issues with hydrate precipitation (this is more of the 'icing' they talk about, because the general public would not understand hydrates and chemical injection etc. This kit was designed in 2 weeks, in ordinary design process terms, this would of taken about 3-5 years.... So they openly admitted it was going to be a challenge... And would take tweaking.... I just love how Bp say this, expect it, then when what they expected happens, the media calls it failure? They will get it working... Plus I know of several alternatives we've been working on at the same pace as this... It's a crap situation... But this happened off western austrailia last year, same thing, and it pissed oil like this for 3-4 months before they could kill it... They will kill this or limit it's damage quicker- there's more then 1000 engineers from around the world working on this right now, around the clock.... This is an Apollo 13 type of mission, thus the belt and braces approach with this coffer dam.