Cement casing procedure

Has anyone ever heard of a driller using bags of cement to line the bore hole by hand, instead of trucking the cement in?

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Permalink Reply by Jack Straw on August 2, 2012 at 5:29pm

It is tough to get a guy with a trowel down the hole.

No, I have never heard of a driller using bags of cement to line the bore hole by hand.

JS

Permalink Reply by Frank Nesmith on August 3, 2012 at 12:53am

My buddy lives by a well and keeps asking when they will bring the cement trucks in, after seeing many pallets of bags of cement. The guard told him they are cementing this one by hand. That didn't sound right so I thought I'd ask here.

Thanks Jack

Permalink Reply by Brian Powers on August 3, 2012 at 2:04am

Frank -

Back in the day, the derrickman would be assigned to cut cement sacks to feed the cement blender, much the same as his job to cut mud chemical sacks for the mud system.

I'm not aware of anyone cementing wells by hand, unless it would be to grout in an uncemented upper portion of a surface casing string, known as a " top job" in the business. I've not seen this done by hand, but I have seen it done by pumping through very small diameter tuning or open ended small diameter drill pipe, depending upon the system. The design of the wellhead system would dictate access method to any uncemented annuli.

Brian

Permalink Reply by Frank Nesmith on August 3, 2012 at 4:03am

Thank you, Brian Powers, for your thoughtful reply. I have leased land, but am no expert. It's nice to come here and get good comments that are from professionals.

Permalink Reply by Brian Powers on August 3, 2012 at 4:59am

Frank -  You're very welcome, indeed. My oil and gas expertise is mainly in the production and petroleum engineering fields, with some reservoir and extensive well completions engineering expertise also . I've sat through hundreds of meetings and conference calls related to drilling, casing running and cementing problems, so my opinions now and in the future on this site will remain grounded within my main ares of experience and exposure.

 

Brian

Permalink Reply by Dave on August 3, 2012 at 6:35am

could be hand troweling to keep the trolls down there

3uq96odaochmjPermalink Reply by 3uq96odaochmj on August 7, 2012 at 12:47pm

not trolls.............skinny chinamen!

Permalink Reply by Jim Litwinowicz on August 3, 2012 at 6:05am

I talked to a guy whose companies does well casings. He told me they have high quality standards for the cement they use and only use product brought in just for well casing.  They barge dry goods up the river and mix the cement on site.They don't use local cement yards to truck it in.

They also use a special mix that keeps the water in the mix. When you finish regular concrete the water will rise to the top. If you get a seam of water along the well casing or along the edge of the drilled hole, that seam can become a pathway for gas to travel.

They also use a lot of additives like hardeners, adhesives, and things to resist cracking. And additives to promote expansion to fill all voids. Like all things in the industry, more complex science than we would expect.

Permalink Reply by Frank Nesmith on August 3, 2012 at 6:47am

Thanks all. This is all very interesting. I love learning new things and I'm at the right place for it.

Permalink Reply by Brian Powers on August 3, 2012 at 7:19am

Jim -
You are correct in that oilfield cement is very different than construction concrete. For starters, oil field cement contains no aggregate (sand or gravel). As you indicated, loads of additives (often very expensive and a great profit margin generator for the pumping companies are available to add strength, accelerate or retard the set time, alter the pumpability, etc.
You are also correct when you state that free water is the enemy of well casing cement, as it can create channel voids or pathways for unwanted gas migration. These channels are tough to detect and can be expensive to repair.
In offshore oil and gas operations, the cement is brought to location in large vessels and in powder form (the cement is ground to extremely fine particle size as dictated by American Petroleum Institute, or API, standards). The dry cement is "blown" from the boat to large hopper tanks on the rig near the cementing unit and kept dry until mixed and pumped. Many of the additives are included in liquid form, which eases handling and reduces exposure to the cementing crews.
Samples are mixed in advance and are generally supplied to the Company Man to ensure the cement sets properly (a set in a sample container or paper cup does not ensure adequate generation of compressive strength, though, these tests are run well in advance of ordering the product, equipment and crews to location). Various integrity testing or cement evaluation methods are available to ensure that the cement is working per design before the next phase of drilling commences.

Brian

Permalink Reply by Jim Litwinowicz on August 3, 2012 at 10:05am

Brian;  Thanks for helping me understand well casing better. It is the most critical part of the entire gas production process and the one that we understand the least. Here's another aspect I wonder about.....how do they keep the the casing centered in the well bore while they are cementing it?  Seems it be very easy for the casing to shift and leave thin spots or even sections with no cement if the casing were to shift up against the well bore wall.

Also, I had been wanting to thank you earlier for all your posts. They have been very helpful in helping us better understand the industry we will be working and living with for the next several generations. Not only will this info helps better understand the risks and rewards but will also help us fight back against the anti folks and their habit of using selective data and/or misrepresenting the facts.  Thanks.

Permalink Reply by monroe on August 3, 2012 at 2:19pm

A CBL or a cement bond log is ran often to show where you have proper cement coverage. Also before you start you circulate fluids (pump down your casing and return on the backside of your casing). You then start pumping cement and you have a good idea if the flow keeps continuing on your "backside" then you have coverage where you predicted, if returns quit your not positive how far that cement got before it started moving out into a zone underground. (you can see what problems abandoned mine shafts can present). The critical part is running a CBL when your done, I assume it is a state requirement but can't confirm that. Not running a CBL when cement job doesn't go as planned (not getting returns) can lead to bad things which is what has been part to blame for the BP gulf well.

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