WorldWide Drilling Resource

Boring Thoughts by Todd Tannehill Owner, Mud & More, LLC My Truck & Your Mud Pump Many articles have been written about this, and it is taught at every mud school; but I still get questions about “outrunning the mud.” Let’s step back and compare this topic to something we all can relate to. Today, while driving my truck, I toggled through the different readouts on my dash. When I got to the one showing my “Average Miles Per Gallon” (mpg) I reset it. Can you believe my F-150 was averaging 27 mpg after the reset? It was right there on my dash, but then the road changed, I started heading uphill, and the average mileage decreased by 15%. In fact, the steeper the grade, the worse my mileage was. Mud pumps have a lot in common with my downhill mpg, and the numbers don’t tell the entire story. Mud pumps are rated based on pumping clear water or a 26-vis- cosity fluid through them. The numbers are real, and they are a way to measure all pumps the same. However, for those of us in the field, we need to make some adjust- ments in our heads based on our actual fluid viscosity or thickness. We need to have a guesstimate of the true gallons per minute (gpm) we are capable of pumping. The manufacturer ’s pump curve, based on clear water at sea level, says our example mud pump can do 40-gpm. Using a Marsh funnel and cup, conduct a viscosity test and f ind out what your true viscosi ty is. Based on this information, the char t shows some field adjustments you can use as a rule of thumb. The logic goes back to “Drilling Fluids 101”. The thicker the fluid (higher viscosity), the slower it is going to flow. When pumping drilling fluids, thicker fluids require more energy to move and will encounter more resistance to flow through the system. Here is a practical example of why this is important. In the horizontal directional drilling world, most drilling contractors feel they are pulling back pipe at a slow enough rate. Pull too fast and you outrun your mud. This means the borehole is not staying full because you are not allowing the hole to replenish as spoils (drilling fluid with cuttings in it) move toward the exit pit. Outrunning the mud and the failure to keep the hole full leads to hole collapse, stretching product, frac-outs, and just a hot mess. So how does this tie together with adjusting our actual gpm of the mud pump? If the mud pump is rated at 40-gpm and we know (after doing the soil specific math) it takes us 1 to 1.5 minutes to pull a 10-foot drill rod, we would outrun our mud if pulling that fast with a 60- to 70-viscosity fluid. If our true, wide open adjusted pumping rate is only 20-gpm, then we need to be slowing our pull to a 10-foot rod every 2.5 to 3 minutes. While this would double our actual drilling time, the math doesn’t lie - and this can keep us out of trouble. This is one example, with one of our drilling disciplines, but having a good estimate of mud output is important and relevant to getting the job done success- fully. As far as my truck’s average mpg, I’m always looking for the downhill route! Todd michele@ worldwidedrillingresource.com 302-684-3197 FAX: 302-384-0643 142 Broadkill Rd. • Milton, DE 19968 www.atlantic-screen.com email: atlantic@ce.net Manufacturers of Slotted & Perforated Pipe ranging from ½” to 24” diameter Atlantic Screen & Mfg., Inc. • Well Rehab. Products • Manholes • Bentonite • Filter Sock • Inline Chemical Mixers • Sampling Bailers • Clear PVC Pipe • Locking Caps Viscosity of Water Reduce Pump Output By Estimated GPM 26 0% 40 40 10-15% 34-36 60 25-30% 28-30 80 40-50% 20-24 This is an example for a pump rated for 40-gpm: DIR 28 JUNE 2018 WorldWide Drilling Resource ®