This seems to be the next hot topic on our barge this days, as we struggled to remove the twist in the chains of the morring legs.
After punching in the nine 35m mooring piles, 15 meters deep into the seabed, we carried on to deploy the ground chain, pretensioned it to the design load (250T) then we laid the excursion limiter load chain (Basically its a length of chain with 12 huge blocks along the chains.) followed by the top chains. After completing one cluster (We have three cluster, three legs each) i was back home before they carry on with the next two. This time i am back to see the next pharse which is the hooking up and the installation of the Mid Water Arch (MWA) and finally the riser installation.
When i return to site again, they jus about to commence the hook-up operation. So the FSO was towed in. That is quite a sight as we get to see the FSO positioned 30m to the rear of our barge. We actually took quite a bit of photos. :P
Now we have all nine mooring chains stopped off at the turret top. The next thing to do is to verify that there is no twist, or rather the twist is within the limitations of the design of the turret and chains. The plan was to pull all nine top chain up to the turret, check on the twists, followed by tensioning it to the required tension and approparite angle. This is to make sure there is even tension throughout the chains even if a storms come in or if we have to abandom the site. But jus when we were heaving the second last chain, the chain got stuck. We proceed to the last one and it was stuck too. And a forecast of 5-6meters waves is imminent hence we pick up anchors and got ourselves approximately 300meters away from the site and standby for the bad weather.
Turn out, the anticipated bad weather didnt come. After waiting aimlessly in the middle of the ocean, we decided to deploy back to site jus at the dawn of Depavali. Turn out, there was an miscommunication with the little tugs boats we had, and they only arrived around 5pm. The set up took away the rest of the day light and we started work right after dinner.
First they got the tugs to assist in removing the jam in the the turret top. After that they got a few riggers to go down on a small boat to attach a tugger to it and coil around the chain, in the required direction to untwist the chain. After they hook up the tugget to the chain, they will pull n try to reduce the twist. After which the ROV will swim along the chains to inspect the twist. For one chain, we need to inspect at least 3 times. That is bascially wat i was required to do at this point of time. Approve/unapprove the twist and the riggers will remedy it if necessary. This untwisting went on for another 20hrs. Inbetween it, we managed to untwist and pull in 4 chains. So there is another 5 more to go.
At this point of time, i am already without sleep for more then 32hrs. Already feeling quite zoombie around but they keep on anticipating that the job would be down soon, as a matter of fact, my work is going to start again coz the ROV have jus been instructed to do another survey on the chains. Chain #4, which is our 5th chain. Yeah!
Oh... I totally went off the point!
Wat i really wanted to post was the discussion we had about the twisting of the chains! Well there was quite a confusion about this twisting of the chain. Basically when the ROV swim from the bottom of the seabed to the surface, should we determine that there is a twist in the closkwise direction, we need to give proper instructions to the people in the turret to retify the twist. But the problem is;
1.) Its is determined that the if u see the twist from the ROV swimming upwards (from the bottom of the sea bed to the surface) the direction of twist would be different when the ROV swims from the surface to the bottom of the seabed. Try to visualise it if u are not sure.
2.) Different people have different perspective to the direction while viewing the twist from the ROV point of view. i.e. You could be thinking of a clockwise twist but the other party could see it as a anti-clockwise twist.
3.) The two operational guys already have a perspective that if a clockwise twist is found, they will remedy it with an anti-clockwise twist. But this is only to the agreement within the team and the ROV. On the client side, TPOT rep and me did not have any understanding in coherence with them. Hence when the first twist was found, we took more then an hour, trying to argue the fact that its a CW or anti-CW...
4.) Further more, there was another TPOT rep who is particular fussy about all the comments made thru. And he yaks and yaks over the radio so many times that it have pissed off the contractor already before hand. As he tried to get himself involved in this mess, he jus makes things worst.
5.) But that is not the worst! Last thing we need is an operational supervisor with a very high self esteem, and always feels that he is right. This time when we view this twist, people on the bridge conclude that there is a 1.5times twist. But he practised the corrective measure wrongly and in the end, starts to pull of some excuses that its our fault! And the more we tried to explains, we are making it worst. He simply dun listen, end up we all gave up and didnt bother to comment...
Well, i guessed it quite a bit of a post. If not a messy one coz i feel i am not in the right state of mnd to blog. Coz i have been up for more then 32hrs without sleep... Still cannot sleep... OMG...
7 years ago
