Memoirs of a GDC intern

Next are the components on the rig floor starting with the noisiest part- the drawworks. It’s a JC-70D type and any one who did science in primary school would describe it as a large winch or drum with a large spool of drilling line wrapped around it. While standing close to it, you can easily understand how it works, driven by two massive DC motors each 800 kW via an air clutch and drive chain mechanism which you can hear whenever the driller activates control and releases the brake. 

Even more amazing is the automatic reeling and unreeling of drilling line as the travelling block is raised and lowered-of course I could understand how the leBus grooving system does all this for even multiple rolls of the drilling line and it would still arrange it so neatly on the drum. The function of the drawworks is to deliver the drill bit to and from its area of operation and to transmit the loads to the rig structure. To enable this, the drilling line is attached to an anchor on the drum on which the wire is spooled, and the wire is fed from a storage spool that I could see on the ground just behind the rig….of course the spool contains enough wire to last for long because I don’t remember there being a shortage of drilling wire that necessitated any pulling in of more wire from the spool. The wire from the spool is fed to the DLA-Dead Line anchor, then to the “fast line” of the crown block at the top of the derrick where it goes through a series of pulley sheaves and down through the travelling block sheaves before passing back to the crown again and onto the drawworks drum and once enough wire is spooled around the system, the rest is securely clamped to the DLA. The “fast line” is subjected to most wear and it’s the one I concentrated on most while lubricating. 

For its working, the drawworks has two DC motors fitted with toothed couplings connected to sprockets that use chains to drive even larger sprockets for more torque. The driven sprockets are bolted onto the drive shaft and do not rotate till the high or low gears are engaged when the driller selects the required clutch setting while raising the travelling block and drill string. Basically, normal operations involved engaging clutches and motors for any hoisting operation and disengaging to allow a free fall and braking to control gravity falling of loads. Of course I had learnt about the pneumatic clutches and this is the first place I saw it being applied…..ever heard of fawick pneumatic clutches…..same principle. 

The next part we looked at was the substructure and as Mr. Nyaga explained to me, I can just describe it as a rugged system of beams….in this case, the whole of the green part that supports the mast, the rig floor and provides a platform for installation of the other mechanical and electrical systems that are on the floor. It must be high enough just to accommodate the BOP stack below it. And while he was explaining this, somebody came and tricked me at first that he was looking for a key to open the V-door and they had to explain to me that the V-door is not really a door….that sounds funny, its just a controlled access route used by crew members to hoist pipe and equipment from the catwalk up the pipe ramp to the rig floor by pulling using the air hoist…which I really liked to operate. I remember while at Rig 4, I was nearly overpowered by a drill pipe while it was being raised and I had to trap it with a piece of rope but thanks to the unity of fellow crew members at GDC, the helped me to do it safely.

The exact type of substructure is a DZ450 that puts the drilling floor at about 10.5 m. 

Of course I know that you too would like to know parts of the rig. In this case, when I asked, I was told that the drilling rigs at GDC are all from China, model type ZJ70D. The ZJ70D is an SCR DC driven drilling rig with a maximum depth of 7 km. However, after staying here for sometime I came to a conclusion that it the hardware is china-made, but the brains are purely German technology.

Right off by just looking at the rig I was shown the mast and derrick assembly. This will be what you see first whenever you see a rig from far. I overheard some new guys who had never seen it before asking what kind of “booster” that was….ha ha ha. The mast is a strong massive tower that supports other equipment like the travelling block and the hook. The mast stands independently on the rig floor and is a welded structure tall enough to allow the drilling crew to set up the drill pipes and other tubulars like drill collars during a trip out. It also has to be tall enough to allow the driller to raise the travelling block above the monkey board so that the derrick man can dislodge and lodge on pipes during POOH and tripping in respectively.

The mast on the ZJ70D is the JJ450-5 type which supports a maximum swivel load of 4500 kN and extends to 45.5 m. It is equipped with a step wise climbing mechanism surrounded by a casing like anti drop mesh of rails for safety and also has many attachments to hold the slings for the safety gear.

I do remember very well my last moment at GDC Rig 4 where we were pulling out 3 joint stands of drill pipes in the rain and arranging them on the floor held by fingers, while tripping out, so as to change the drill  bit. Tripping pipe in stands is much faster as it helps hasten the tripping process.

Those of us who do not know the monkey board-is the platform up on the mast where the derrick man works. The walkaround or watertable is the platform that permits access to the crown block at the top of the mast. The crown block is the uppermost system of pulleys where the drilling wire passes and I remember going there once to grease……very epic experience. The safety at GDC is very paramount as policies are in place to ensure no one is injured. Use of safety gear for all height operations is mandatory and the drilling supervisor and your fellow team members have a responsibility to follow up and ensure you are safe.

I know am supposed to take you through my day three but before that…..today I just did my CAT 1 on Computer Controlled Manufacturing (CCM). I had a rather smooth time explaining the use of pneumatic valves in speed control especially thanks to the knowledge passed to me by Mr. Nyaga, one of the best technicians at GDC Rig 2 who gave me a lot of hands-on knowledge on Rig Mechanical systems from hydraulic, pneumatic and Structural Mechanics…..very beneficial information that I bet I would not have found anywhere. And how is speed control applied on pneumatic systems on the Rig?

The pneumatic system does the braking of the drawworks while doing POOH and RIH operations both automatically using the two protective limit and safety devices, and by the driller applying brakes. The whole system is pneumatically activated and I remember interpreting the circuits at the Maintenance Cabin, Wow!

Ok, this is not the day for this, On day three was arrival day at the field, Menengai. Here comes the good part…..our Van. I do appreciate on behalf of my fellow interns, the transport that the company gave us. This was the best part of this hospitality at GDC, a company van with a designated driver just for the attachees was just awesome. We really appreciate Godana, our driver from day 1, for being very kind accepting the challenge despite the fact that he had other errands to run, like being the Head of Camp at Menengai. So, to cut it short, he picked us up at 7am from Generation house parking to Menengai, more specifically dropped us at Rig 2 on his way to the camp.

On this day, we were all new and knew nothing about drilling Rigs and so we asked many questions as we drove past Kabarak, into Menengai, Barrier and even had more questions when we saw the “booster-like” things for the first time. We went past Rig 1 and could see Rig 3, Rig 4 before we alighted at Rig 2 and were handed over to Mr. Too, the Rig 2 Maintenance Engineer. Of course I had done a bit of research and watched as many videos as possible about drilling rigs and so I was the one helping answer some questions that I could while Mr. Nyaga helped us understand more.

So, on being welcome here, we just got to work. Rig 2 was on Rig down, i.e being dismantled in readiness to be transported to another site that was being prepared. Wow, Mr. Nyaga told us that we were the luckiest attachees because we would gain maximum experience as we would see every part of the Rig and this didn't make sense till later….we really learnt a lot.

So Mr. Too gave us our first task, stating clearly off course that at the Rig we would learn more by experience and doing a lot rather than just watching people do things so we were greatly encouraged. Our task for most of that day was transferring items from a KOOMEY to a store cabin for better storage and arrangement. Some of the items we transferred included Generator and Compressor filters for oil and fuel,  Valves and transducers mostly Rexroth Control valves…yeah German Technology running Chinese Rigs; Motors etc.

I remember transferring this SKF induction heater from the KOOMEY to the store. You may be wondering just what this is…..it’s used to insert bearings for example where the bearing is supposed to have a tight fit so its slightly smaller, so you use this heater to expand it a bit before you do the fitting.

We all did some good teamwork here and all parts were well arranged in the store. Unfortunately, it was too late for this day and as we slowly took our 4 o’clock tea which I still miss till today, we got to know even more people at the rig as we waited for Godana to pick us.

Mr. Nyaga promised to do a proper orientation for us on the next day and as we left for Nakuru town, we looked forward to the next day with a lot of enthusiasm.

Which sane person stays on unpaid attachment for three months? This is one of the rude claims I could make before I joined the company for attachment in February 2014. I thought like,”Since this attachment is unpaid, I will stay for three months just to fulfill my department requirements and then I will be gone!” Ha ha….What happened? This is the journey I will be taking you through this blog “The memoirs of a GDC  (Geothermal Development Company)  intern”.