Export gas control

So I'm just back from another offshore visit, this time setting up a new control scheme for automating the export and gas injection flow rates.

Not all gas is sold. This particular platform has a contract with a nearby installation and exports some of the gas. The remainder is put back underground to apply pressure on the well and resulting in more oil. The design of the original control scheme was very poor so that automatic control was not possible. For years past, the operators have continually adjusted the valve positions to maintain the desired pressures and flow rates. The new design has fixed that. The only remaining issue is to convince the operators that the controls can be left in automatic!

I'm offshore again on Tuesday. Lucky me!

Too much to do, too little time

Things are really busy at the moment. Good for the bank manager, but pretty poor for the social life! The offshore work has been nose-tailing for weeks past and there's no sign of it letting up over the next couple of months.

I received one unexpected break over the weekend. I was due offshore last Thursday with a 0950 check-in. There was thick fog and no flights were leaving Aberdeen, so I had to sit around until 1800 until I was sent home with orders to return the next morning at 0600. And that day was just as bad. About 5pm, I phoned the client and requested a postponement of the visit for a few weeks because there was still no sign of the fog lifting.

So I ended up with a few free days to catch up with report writing and other onshore activities.

Compressor surge line mapping

No sooner back from my holidays when I'm out to the North Sea again. This was a short three day visit to identify the surge position of three centrifugal gas compressors.

To explain to those of you who don't know these things, a centrifugal compressor uses spinning blades to increase the pressure of the gas. Problem is, if this type of compressor doesn't have enough gas flowing into it, the gas suddenly changes direction and rushes backwards through the blades. This is 'surge' and potentially results in millions of pounds of repair work. To protect against this event, there's a pipeline called the recycle line installed from the compressor discharge to the compressor suction (a bit of a simplification!). A valve in the pipeline (the recycle valve) is opened whenever there is a risk of surge. The difficulty is to find out at what point the valve needs to open. Although there are theoretical techniques, the most accurate method is to push the compressor gradually towards the surge point until the process conditions indicate that surge is about to happen. And 25% of my offshore work seems to involve this operation - to try to identify where the compressor will break, but without breaking it!

As it happened, the tests went like a dream. In fact, they always do, but it's a nerve-wracking experience. Not a time to have someone asking you lots of questions and why is it there's always someone who drops a spanner just when you're listening for the surge to start? Despite all the many times I've successfully completed surge tests, I always get a fit of hysterical giggles afterwards.

Offshore survival refresher

I've just returned from a holiday in Malaysia. Since my offshore survival certificate is about to expire, I completed my refresher training today. This has to be done every four years without exception. If the one day refresher course is not taken before expiry of the certificate, the complete 3 day course has to be repeated.

The course is rather good fun and comprises fire fighting and helicopter escape. For the fire fighting component, we had to put out various types of small fire with different fire extinquishers, after which we had to find our way through a smoke-filled room. The helicopter escape is carried out in a swimming pool with a helicopter simulator looking remotely like the cabin of a helicopter. After strapping ourselves into the cabin, we take up the brace position as the helicopter is lowered into the water. After a few seconds submersion, we have to exit by the doors/windows and hopefully float up to the surface. The final escape involves the helicopter turning upside down in the water.

All good fun in retrospect, but cold and wet at the time, especially after two weeks in SE Asia! But that's it for another four years.

Onshore again

Finally left the rig at 14:30 yesteday. There was a big mix-up about baggage weights which almost resulted in someone being thrown off the flight. It turned out to be a confusion between kilos and pounds!

Fogged in

Yes, it had to happen! We waited for the chopper until 8 pm and after three attempts at landing in poor visibility, it had to give up and returned to the beach. The other lads have already completed three weeks offshore and, in accordance with the rules, are not allowed to do any more work and I'm getting ever closer to my holiday flight to Singapore. Last Easter, I was stuck offshore for five days in the fog, but that was in the Southern Sector and rarely happens up here. With a bit of luck, the fog will lift during the morning and I'll have the nervous wait for the chopper as it clears the backlog.

Waiting

Typical! I agree to wait for the last flight so that I can help finish off the controller problem and what happens? The flight is not until 6 pm. Great! One requirement of offshore life is getting used to waiting. Always have a book with you, 'cos you'll get lots of time to read it. Still, it gives me time to get my report started.

And today's second gripe - some of my test equipment failed to turn up, but sure enough its here now, just on time to lug home again.

Muster

We've just finished the fire drill exercise, which is a common event throughout the North Sea usually on either the Saturday or the Sunday. We got off light this time because it was only an internal muster and not out in the freezing cold by the lifeboats. The muster is supposed to be a surprise event, but the rumours has usually gone around before hand, so everyone is hanging around carrying warm clothing. I got 'incinerated' a few weeks ago in a drill because I didn't listen to the instructions and ran into a stairwell engulfed by pretend flames.

I'm due off here tomorrow, which is good because I'm on holiday from Wednesday. Its best not to cut it too fine in case the flights are delayed or cancelled due to high winds or fog. As it is, I've been asked to stay on until the last flight because I've made a breakthrough in the liquid carryover problem (as usual everyone was looking in the wrong place).

There's roast beef - it must be Sunday

After a short time offshore, the days blend into each other and its difficult to remember what day it is. Weekends tend to bring more football on the box and Sunday brings Sunday lunch. Otherwise, its business as usual. I didn't forget to reset my alarm clock to Summar Time and even went to bed last night an hour early. No one else seemed to forget either, except for one guy who changed his clock a day early!

That's my lunchhour done, so back to the grindstone. Beginning to make some progress on the liquid overspill problem. Everyone has been concentrating on preventing the liquid getting into the vessel, while the real issue is fixing the controls so it can be emptied again.