Lightning Protection and Drilling Rigs

Maybe because they are heavy metal structures with what is basically a giant ground rod (well casings) right underneath them?

Like tcmtech said and why don't you take a look at this IADC incident report.

http://www.iadc.org/alerts/1998_Alerts/SA98-22.pdf

The main reason there is not lighting protection on most drilling rigs is that there is no law or regulation that requires it at least not in most states ( I know Florida lighting protects everything due to the number of stikes it recieves per year). And in the minds of most Americans, if it isn't a law or a regulation then it can't be much of a safety hazard. We will only make it a law or a regulation when there is a disaster and people are killed or seriously injured. At that time everyone will claim plausible deniability, and say some one should have done some thing sooner.

Sad but true commentary.

very interesting. So, there's no IEEE or API or related documentation I can relly on?

Thank you...

Just a guess here, but ...

The rig will provide a low inductance and very low resistance path to ground. Therefore the lightning energy should be "happy" to flow down the rig to ground.

The lightning rod and cables down, even if very good, will probably have higher resistance and inductance than the rig. Therefore, energy from the lightning rod system would be at risk of jumping from the down cable to the rig and various points along the path of the down cable. Thus, risk to people, equipment and flammable liquids/gases.

Running the energy down the rig is probably the best thing to do. Adding lightning rods to the rig would be good to pull the lightning out of the air before it has a chance to strike a person.

but with the energy flowing thru the mast of the rig, is this not dangerous for people working on the rig floor, mast, monkey board and other critical places of the rig?

The rig is the best conductor and offers the path of least resistance. See other comments.

Suppliers of oil field equipment are well aware of the dangers of lighting strikes and provide appropriate grounding where required. When ancillary equipment is mounted on the rig platform an appropriate interconnect has to be provided. It is up to the Field Service Support contractor to insure that all of the equipment and structures are properly grounded.

This does not mean that there are no codes or standards that apply to the construction and operation of drill rigs. This is not my field but experience in other areas indicates that [in the US in particular] when a structure is erected on which or in which humans will operate, building codes, electrical codes etc apply. And before the structure can be occupied or operated a Certificate of Occupancy has to issued.

Terminology and process will vary from state to state - but you get the picture.

thank you for the answer.

I forgot to mention the technical parts that may be seriously damaged by a ligthning, like the Top Drive or SCR system do to a bad grounding.

Its a lot like sailboat grounding and bonding.

<www.ifas.ufl.edu/sgo71>

I have been around well rigs for 40 years or more and have never seen one grounded properly. They really should be. I do know of at least one electrocution from an improper grounded welder but not direct from lightening. If there is heavy lightening in the area get in the truck cab (Faraday cage) and stay put until the lightening is over. use the sailboat information as a basis for grounding an operating well rig. Not all casing is metal, fyi.

this is a good insight information. Thank you.

In my case, in particular, this land rig is based on top level ground, at 4,000ft. In this time of the season, rainy season for this part of the world, this place is a perfect target for lightning discharge. how to protect the equipment and the people working on the rig? Why a ligthning rod is not used? Because it can atract more ligthning to hit the mast?

website is wrong above sorry. Here is the correct site;

www.edis.ifas.edu/sg071

I cannot enter the webpage you posted

www.edis.ifas.edu/sg071

regards

This reminds me of an old joke:

It seems Bob and Linda went on their honeymoon to a ranch in Wyoming to hunt elk. While out on the trail Linda's horse rear up and then calmed down. Linda said to the horse "That's one". A little further along the trail Linda's horse did the same and Linda said "That's two". A little further down the trail the horse reared up again and Linda said, "OK that's three" She dismounted from the horse, took out her gun and shot the horse dead. She turned and mounted behind Bob who was stunned by what he witnessed. He turned to her and said, "Are you crazy, you just killed a fine horse." Linda whispered in his ear, That's one."

You know the couple stayed together in harmony for the next 40 years.

Anyway, here is my correct third attempt to post the site. For some reason my reply box will not allow me to paste. I will try to figure it out unless their is some magic I am missing. Sorry oops.

www.ifas.ufl.edu/sg071

Yeah, I found the answer.

http://edis.ifas.ufl.edu/sg071

not sure about rig in USA, Static (not floating) offshore platforms in the North Sea are grounded. Most of the larger static rigs are "Nailed" to the sea bed and are connected the the well casing which in many cases is over 3000ft into the seabed and there is more than one well. As for lightening strikes, the top of the rig mast is over 200ft above sea level, all metal and earthed, so I'd say its all well grounded. The land rigs I've worked in Chad, Syria, Libya and Oman were all earthed with a very large cable to a earth point at the well site and again the metal structure of the rig was in contact with the well casing, with many of the wells drilled to a depth of over 6000ft.