Permanent plugs have successfully been installed and pressure-tested in the notorious H1 well that blew out on August 21, 2009, in the Timor Sea and spewed oil and gas for 71 days. Some information is now trickling out as the Australian government investigates the causes and consequences of the Montara / West Atlas blowout and ten-week oil spill. News accounts have focused on the drilling contractor’s apparent failure to install a basic piece of safety equipment called a corrosion cap. This seems like a serious mistake for a major offshore drilling contractor like Seadrill. But we’re not yet sure that the lack of this cap could, on its own, cause the well to blow out.
Upstream’s coverage provides the most technical detail. Apparently there was an existing weakness in the well due to a poor cementing job. Ho hum, cement…but as they say, the devil is in the details…so bone up on well drilling (especially the section on cementing) before you go much further:
the source of the flow was in the 244 millimetre casing and the most likely cause of that was a channel in the cement in the shoe track casing
This article also raises a lot of questions. It states that in August PTTEP determined no corrosion cap had been installed when the H1 well was suspended in March. Yet on August 20, “the corrosion cap was removed” to “clean corroded casing threads,” the cap “was not reinstalled,” and the well blew out the next day:
- Does this mean that Seadrill actually had installed a pressure cap on the H1 well?
- If so, when exactly did that happen?
- Was the removal of that cap to “clean corroded casing threads” unusual, or is that a common thing to do?
- If common, what are the safety procedures during this operation, and were they being followed?
- Was Seadrill (or some other contractor?) doing that work on the H1 well at the same time they were actively drilling a new well at the platform, as initially reported?
- If so, is that allowed, and does it conform with industry standard practice?
- What has been done to suspend or abandon the well that Seadrill had been drilling when the H1 blowout occurred?
- What will be done with the other suspended wells and the Montara platform structure?
- Why was the bulk of the fire centered on the West Atlas rig, rather than on the Montara platform? Check out the pictures and spectacular video.
- This suggests to me that the well that was being drilled is the one that ignited, rather than the H1 well. If so, why?
Wonky stuff, for sure. But it’s important to get all of these questions asked, and answered, before the government closes the books on this investigation, so we can be sure we know what really happened.
Meanwhile, another tropical cyclone is making a Montara drive-by. This time it’s Magda, a Category 2 storm with sustained winds of 60-70 knots. On January 21 at 0:50 hours Zulu time, this MODIS Terra satellite image showed the eye of Magda to be about 186 km southwest of the Montara oil platform. The storm is moving almost directly south, and should not pose a threat to operations as crews are now assessing the structural integrity of the fire-damaged platform.