From the Houston Chronicle's NewsWatch: Energy blog:
In a research note this morning, the folks at Tudor, Pickering, Holt & Co. gave a good explanation for why using the new containment cap to shut-in the leaking Macondo well is not a good idea.Previously:
The note says that though BP mentions the potential to shut-in the well with the new sealing cap, this is very unlikely and potentially dangerous.
Shutting in the well at the seafloor LMRP cap will result in pressure build up inside the well/BOP (10,000psi+). With the 9 7/8" production casing compromised (very likely not sealing at the surface) due to flow up the back-side (uncemented annular space behind the 9 7/8" casing), the high pressure would be exerted on the 22", 28" and 36" casing strings. The burst rating on these larger casing strings is probably much less than 10,000psi. Therefore, if the Macondo well is shut-in at the LMRP cap, there is significant risk that the larger casing would rupture near the surface of the well, resulting is an "underground blowout". In that bad, bad, bad scenario, oil and gas would crossflow from the Macondo reservoir, up the well and out into the shallow formations.This is negative for 2 reasons: 1) if the larger casing ruptures near the seafloor, oil and gas could leak uncontrollably around the wellhead assembly or from the seafloor near the well (making containment much more difficult). 2) the larger casing provides the structural support for the wellhead, BOP, and LMRP assemblies - think of it as a piling. A shallow rupture could compromise the mechanical integrity of the seafloor equipment (stated simply...in a worst case scenario the BOP could become the leaning tower of Macondo).Note that BP is aware that shutting in the well via the new sealing cap is not the end all to the well....MORE
"A Real Worst-Case Scenario for BP: 20m barrels, $560 Billion Damages" (BP)
Oil spill: Even worse worst-case scenarios! (BP)
Oil Spill: The Worstest Worst Case Scenario- A Sinkhole Swallows Everything (BP)