BP Gulf Oil Leak Well-Head Repair … an anthology III

Sunday morning (7/11/2010) finds the Flange Transition Spool (FTS) already hanging near the well head as preparations are underway to make the installation:

Flange Transition Spool being prepared for installation

I am unsure what the tool is in the foreground. It was on screen in the shot above as I logged on Sunday morning and I didn’t notice it after a short while. Notice in this shot there are three ROVs … the lights off in the gloom to the right of the view, the glow of lights behind the mechanical arm (upper left) and the ROV holding the tool.

Well stack w/o old flange

The image above shows the bottom flange, sans the old top flange removed in the early hours of the morning. Note to the right the white, inverted “u” dispersant injector has been reinserted directly into the well

The method BP is going to use to guide the FTS into the correct orientation above the well flange is through the use of tapered dowels that fit into holes in the flange made for that purpose. You can clearly see the dowels in the image below.

Left image - guide dowels built into the bottom flange of the FTS (click to see a larger image)

However, BP is using a clever way of making sure they are able to find the correct holes for the dowels. In the image on the left above, note the slim cables attached to the bottom of each tapered dowel; the ROV operator threaded each of these cables into the correct hole in the bottom flange prior to moving the FTS into position. By keeping tension on these cables, the FTS will be guided into the correct orientation even though the view will be blocked by the oil plume once the FTS is positioned within the plume.

Flange Transition Spool being moved into position adjacent to the well (click image to see an enlarged version)

The images above show two views as the Flange Transition Spool continues into position above the well.

BTW … I believe these two images are from ROVs controlled by another support vessel, the Boa Deep C, though I haven’t found that ship in the readily available information on BP’s site. These two ROV’s continue installing the FTS.

FTS close to the well

Above, the FTS getting closer to the well. The images below show the FTS in the plume, being positioned directly over the well. Note the tapered dowel and the cable being pulled taught by another ROV somewhere off camera.

FTS within the oil plume, directly above the well

In the next shots the FTS is in position and being lowered onto the well-head flange:

FTS being lowered onto the well-head flange (click for larger image)

Things are looking good!

A

FTS almost in place

Just a litttttttle bit more to go ….

Almost there ...

But it’s stuck. They take a closer look …

Why won't it drop further?

Okay … let’s try to raise it up slightly and then put it back down …

Raise the FTS ... just a bit

Okay … now lower it again and let’s see if it will seat itself:

FTS seated all the way! (click on image for a larger version)

Next, remove the external sleeves that held the bolts in place and begin screwing each into the lower flange.

Removing sleeves from flange bolts

Note the string attached to the white sleeve wrapped around each bolt … the ROV operator grabs the string and gives it a jerk and the sleeve pops off, allowing the bolt to fall all the way into the hole until it hits the threads.

Flange bolt sleeve removal

As before with the removal of the bolts, the ROV operator places each of the removed sleeves onto a tray on the old BOP (blowout preventer)

Stowing the bolt sleeves

Each bolt is then “hand” tightened:

"Hand" tighting the bolts

At this point I had plans to visit some friends, so I left. When I returned, I wasn’t really sure what it was I was watching, but after a few minutes I guessed that another type of hydraulic socket tool was …

Hydraulic tool to fully tighten the bolts

… torquing down the bolts. As you watched, the ROV camera would watch as the operator placed the tool on a bolt and then the view would switch to …

Monitoring the hydraulic pressure gague

A pressure gauge. As you watched, the gauge would move from zero up to more than ….

Hydraulic pressure torquing the bolts

… 6,000 PSI (pounds per square inch). The operator would drop the pressure then reapply several times before moving to the next bolt. It seems that the highest pressure reached on each bolt was around 6.600 PIS or so. I didn’t follow every step, but it appeared the operator torqued each blot at least twice. I’m not sure how many foot-pounds relates to 6.600 PSI, but I bet it’s more than what I used to torque the head bolts too on my 427 cubic inch Chevy I had in my flat bottom ski boat!

The last operation I watched last night was something I didn’t understand. An ROV holding some sort of an instrument moved to the base of the well casing where it came out of the sea floor …

Instrument at the sea floor

The instrument was placed against the casing as shown in the image below …

Test instrument placed against the well casing

The instrument was held in place for several minutes, then moved 90 degrees and the process repeated for a total of four times. My first thought was that it was some kind of ultrasonic flow measuring device, but the ones I’m familiar with require sensors on both sides of the pipe, and for such a large diameter pipe, the sensors would be much longer.

I then assumed the instrument was some sort of device that measured the stress on each quadrant of the casing to insure the added weight of the Flange Transition Spool wasn’t causing undue stress on the casing. However, when completed at the bottom of the stack, the ROV relocated to …

Instrument placed in the oil plume ...

… the top of the stack and put the instrument directly into the oil plume! Some kind of flow measurement device?

Things began to slow down, so I called it a night. I’ll pick up with Monday morning’s activities in the next post.

Related posts:

1. BP Gulf Oil Leak Well-Head Repair … an anthology II
2. BP Gulf Oil Leak Well-Head Repair … an anthology
3. BP Gulf Oil Leak Well-Head Repair … an anthology part IV – UPDATED
4. BP Gulf Oil Leak Well-Head Repair … an anthology part V – UPDATED