WorldWide Drilling Resource

17 WorldWide Drilling Resource ® SEPTEMBER 2013 Drilling Fluid Updates by Ray McLarty Drilling Fluids & Grouts Questions & Answers Question I’m at a site in Central Mississippi. I ran out of the polymer I most often use when drilling in clay formations. I have already mixed one five-gallon pail and part of another in the mud system. I need to add more polymers. Another drilling contractor has offered me the use of a couple of pails of the product he uses. It is a different brand than the one I have been using. Can I mix his product with the product I already have in the system without any problems? Answer I wouldn’t recommend this as a reg- ular practice; however, I have seen more than once where two similar products from different manufacturers have been used successfully in conjunction with one another. As always, I recommend you contact the manufacturers of the two products and confirm this. I gave you the name and phone number of the local representatives of the two prod- ucts. I know both of these individuals well. You can contact them and com- pare the info they give you to the info I gave you. Question After adding EZ-MUD ® to the drilling mud, how much time is required for the EZ-MUD ® to break down swelling clay? Answer EZ-MUD ® is a PHPA (partially-hy- drolyzed polyacrylamide) liquid polymer. PHPApolymers do not break down clays. They coat swelling clays and shale to prevent hydration, thereby preventing the problem of swelling clays from occur- ring. This is the reason you should always add PHPA polymers to your mud sys- tem before drilling into the clay formation. In fact, it is best to mix it immediately after thoroughly mixing the bentonite drilling mud. If you wait until after you drill into the clay formation, the clay will hydrate and swell, creating a much big- ger problem. Question Is there any reason to use bentonite pellets rather than HOLEPLUG ® to place a seal in the well? Answer In my opinion, no! In the past, before HOLEPLUG ® and equal products were available, the only dry material that could be placed at any depth in the well was compressed bentonite pellets. Today, we have naturally occurring bentonite such as HOLEPLUG ® that can be success- fully substituted as a replacement for the more expensive pellets. I personally don’t think a 50-pound pail of pellets is worth four to five times the cost of a 50- pound bag of HOLEPLUG ® . I also do not believe the permeability of a foot seal of tablets is that much better than a foot seal of HOLEPLUG ® . However, pellets are often written into the well specs and, in those instances, pellets must be used. Note: EZ-MUD ® and HOLEPLUG ® are Baroid IDP products. EZ-MUD ® cross reference products are: CETCO ® INSTA-VIS™ PLUS M-I SWACO POLY-PLUS McLarty cont’d on page 18.