WorldWide Drilling Resource

Boring Thoughts by Todd Tannehill Owner, Mud & More, LLC Safe Polymers for Water Well Drilling in Clay This month, I thought we would look at PHPA (partially-hydrolyzed polyacrylamide) polymers and use a couple questions right from a mud school. Interesting side note: When Internet searching “PHPA”, you should add the word “polymer” with it, or you may end up on the Professional Hockey Players' Association home page! For this article, we will instead talk about the silky, light-colored polymer which is impossible to get off your hands without breaking it down with bleach. This is a personal observation from a drilling show where the men’s room soap was replaced with a liquid version of the polymer. It wasn’t me! Question: What are PHPA polymers, and what are their functions? For us in the drilling industry, PHPA polymer is a synthetic polymer which is especially good at delaying clays from swelling in drilling, grouting, and sealing situations. Depending on your application, many manufacturers offer PHPA polymers in liquid and dry formulas to get the job done. (I am using PHPA in place of brand names you most likely have on your rig today. This is to be fair, because there is not space here to list the many brand names the polymer is marketed under.) Drilling When drilling in clay or shale conditions, PHPA is especially helpful in coating the cuttings and inhibiting them from swelling while they are evacuated from the borehole. In nonbentonite slurries, it also helps to keep the integrity of the bore and prevent wall swelling in a clay formation. Many brands are certified to NSF/ANSI 60 drinking water standards, making them safe and approved for drilling water wells in the U.S. They are used in many drilling applications, including ground source climate control loop installation, minerals exploration, and horizontal directional, to name a few. In drilling operations, it is important to mix the bentonite first, then add your polymers. If using a recycling system, you will want to avoid long-chain PHPA polymers, and instead opt for a short-chain, low- viscosity type. This will reduce screen blinding and be better than a dispersant which incorporates the broken-down clay into your system and makes the mud harder to reuse. Air rotary drill operators will also add the polymer to their drill foam to make it stiff. The polymer strengthens the foam bub- bles, allowing them to carry larger or heavier cuttings to the surface. Grouting and Sealing Before the one-sack grouts were introduced, two-step grouts were a very common grouting material. Today, many well drilling contractors are still using the two-step grouts for many reasons. A two-step grout is made by adding a PHPA polymer to fresh water, then slowly adding a granular sodium bentonite to the water/polymer mix until the grout is an oatmeal-like consistency. The grout is then pumped through a tremie line downhole. Different from drilling fluid, the PHPA polymer is added first to coat the incoming granular bentonite and delay it from swelling until it is put in place downhole. Question: How do I know if the product I am using is a PHPA polymer? Company-produced technical data sheets (TDS) are vague in identifying polymers by type - company representatives are not. They will identify their products in the field or during the polymer section of a mud school. The TDS will identify if the product is recommended for clay or shale formations. As far as long-chain or short- chain, you will need to refer to your man- ufacturer. There are many other products used in clay which are not PHPA type polymers. Some work okay, and some outperform a typical PHPA in sticky clays. The downfall of these other prod- ucts is they are typically not NSF certi- fied and therefore should not be used in water well development. Todd Todd Tannehill may be contacted via e-mail to michele@ worldwidedrillingresource.com www.filmarkproducts.com PO Box 60249 Midland TX 79711-0249 432•563•5941 432•563•5942 (fax) 5” File Hard Liner ................................$190.00 Liner Packing T.T. 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