Problem 13. ...mix...sack of Class A cement slurry...4% bentonite...standard water...weight of the slurry (pounds): (A) 161; (B) 159; (C) 157; (D) 155.
Slurry volume & density calculations for this exact situation are on 5 CMT 2. Note there are 4 components: cement, cement water, additive, and additive water. They combine for 11.34 gal/sk & 14.18 lbm/gal as shown on the page. Multiply them for 161 lbm/sk (A).
why not just mc+mw+ma+mwa to save 2 more minutes
ReplyDeleteSure. But to be ready for a more difficult/confusing problem I prefer to show the long road. Note I show the entire thing in the Guidebook too so yes that makes it easy to tears if you are just cranking the answer. But note anything could be asked here, and I like to work it long for that reason.
DeleteI remember talking to a coworker who spent 5 minutes on an easier problem since they couldn't believe it that "simple" and was searching for the "trick", until they finally were convinced it really was that easy. She passed. And a lot of guys who jump to the conclusion right away do indeed find they got tricked in the end, for example: https://www.linkedin.com/pulse/first-you-dont-succeed-david-vaucher-mba-meng-eit
The Halliburton Redbook gives slurry properties for Class A with Bentonite @4% of: Slurry Weight 105lb/cf and Slurry Volume of 1.55 cf/sk. 105 * 1.55 = 162.75 lbs. Is it correct to assume this does not give the correct weight because it utilizes a maximum water requirement of 7.8 gal/sk instead of the 5.19 gal/sk shown in the guidebook? Also, what is the reference to T3.6 shown on the same page (5 CMT 2)? Thanks in advance.
ReplyDeleteThe T3.6 is table 3.6 from TS2 I believe. I woudln't read too much into cement problems; yes, know the word problems but the calculations are generally just plug-n-chug.
DeleteOn the test would a question like this have a larger spread? I used the bentonite requirements from the SPE Text Book Series 2, Applied Drilling Engineering (1.3 gal/2% in cement). Using this value I calculated the weight to be 162.8 lbs. This would put me closer to (C). All my other values matched the guidebook. Is there a reason why these bentonite requirements do not match?
ReplyDeleteI think you are right; it's a grey area and I need to create more spread. I'll update the exam for that.
DeleteFor this problem, Table 2.5a in page #68 of SPE Reference Guide has lb/gal and gal/sack of max water given for Class A cement with 4% Bentonite. Can we not use that? If I do use that it gives a different answer though. 14.1 ppg * 7.8 gal/sack = 110 lbs. I am not understanding why this method gives a different answer. Any idea?
ReplyDelete99% of the time errors here are solved by using three significant digits on every number in the calc. But feel free to get a photo of the problem and email me at mdavidgo at gmail. Kindle often won't update the older tests so I with a pic I can verify what "version" you have.
Delete99% of the time errors here are solved by using three significant digits on every number in the calc. But feel free to get a photo of the problem and email me at mdavidgo at gmail. Kindle often won't update the older tests so I with a pic I can verify what "version" you have
Delete