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.

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

So … last night we left off at the point where BP was removing the flange bolts using a hydraulic socket wrench.

View of the hydraulic socket tool on one of the flange bolts

Notice the bolt to the right of the one with the wrench (not the larger object directly adjacent to the bolt the socket is on … I believe that is an alignment pin, but certainly not a bolt head. I’m referring to the second object to the right of the bolt that the socket is on). It appears the flat surfaces have at some point been damaged. The image below provides a better view:

Bolt on the right shows damage to a couple of its hex surfaces

Not to worry! Just go to your trusty tool box and bring out the Dremal rotary tool … an industrial strength Dremal if I do say so!

Industrial strength Dremal rotary tool being used to grind burrs off of hex bolt in image on the left (click on image to see an enlarged version)

Below is a second view of the grinder seen from both ROV cameras:

Grinder seen from both ROVs (click image to enlarge)

The next image shows the hydraulic socket wrench loosening the now-cleaned bolt:

Socket on bolt that had the burs removed with grinder

Same view as the last, but from both ROVs (note the polished surface … as a the result of grinding, of the bolt below the socket in the image from ROV 1):

Damaged bolt removal seen from both ROVs (click image to enlarge)

ROV 1 now begins to remove all the loosened bolts:

ROV 1 using one of its mechanical arms and "hand" begins to remove the loosened bolts

The “hand” at the end of the arm is positioned directly above each bolt and then rotates counter-clockwise, unscrewing each bolt.

Bolt almost removed from flange

I was surprised that as each bolt was removed, the ROV would back away from the stack and move to a shelf located somewhere lower on the stack and drop each bolt on the shelf, rather than just drop the bolts to the ocean floor. Keep your work space tidy!!

Meanwhile, in the next image ROV 2 breaks out the trusty rotary wire brush and begins cleaning the surface of the outer flange:

Rotary wire brush cleaning the outer flange surface

It is pure speculation on my part, but I suspect that the Flange Overshot Removal Tool (FOLT), designed to remove the damaged flange, is designed with relatively close tolerances. BP cleaned the outside of the flange to make sure there are no large burrs or other obstacles on the flange that could inhibit the placement of the FOLT, shown below:

Flange Overshot Removal Tool ... used to remove the flange

Wire brushing continues to clean the entire outer surface of the flange:

View of wire-brushing operation from both ROVs (click image to enlarge)

I mentioned the “tool box: earlier. Below is a shot of one of those tool boxes:

Tool box

Note all the different colored rope loops with different tape markings; a very simple and clever way of identifying different tools IMHO. I’s say these guys may have done this type of thing once or twice before Below is a second view of the same tool box:

Another view of one of the tool boxes

At this point it’s almost midnight Saturday evening in the Gulf and the activity that I can see via the various ROV cameras is slowing down, so I decide to call it a day and go to bed. As it turned out, BP was apparently able to remove the flange around 12:30 or 12:45, so I missed that operation completely.

In the next post I’ll pick up the operation that began the next morning to install the Flange Transition Spool, seen in the image below:

Flange Transition Spool being tested