WorldWide Drilling Resource

17 WorldWide Drilling Resource ® FEBRUARY 2015 Know Your Directional Drilling Bits Adapted from an Article by Mike Magee and Shannon Houk Horizontal directional rock drilling brings a number of technical challenges. The bidding process alone is challeng- ing because oftentimes the customer requesting bids has limited information about ground formations. On many jobs, dri l l ing contractors find themselves guessing about conditions they will en- counter. Choosing the correct bit is one of the most paramount decisions a drilling professional will make. The effectiveness of a drill bit varies by formation type. There are three types of formations: soft, medium, and hard. Knowing your options and what formations each type of bit is designed to drill is essential to the prosperity of a job, or time and money wasted. Many different cone cutters have been designed to cut variants of rock, thus a problem arises when the bit transitions from one rock layer to anoth- er (for example: from limestone to shale to clay to dirt). No cone cutter in existence is designed to cut rock formations of varying hard- ness, so the drilling contrac- tor is forced to choose a cutter type for the rock they think wi l l be encountered most. In many cases, the only choice is to use multiple types of bits and hole openers to accommodate changing layers. By using a PDC (Polycrystalline Diamond Compact) bit, the cost of rig standby time can be significantly re- duced since fewer trips of the bits are needed in the hole. The Volcano ® PDC hole opener from Diamond Drilling Industries (DDI) offers an improved process for enlarging and cleaning the predrilled pilot hole for future installation of (including but not limited to) gas pipeline, waterline, sewer line, and telecom products. The DDI Volcano PDC hole opener is a drill bit that can be pulled or pushed while being rotat- ed by a horizontal directional drilling (HDD) rig through the predrilled pilot bore. As the rig rotates the bit, PDC cutters scrape and cut the rock forma- tion. Nozzle ports installed in the bit’s junk slots are situated in a specific con- figuration allowing drilling fluid to be pumped through them, sending rock cuttings back to the surface. Rate of penet rat ion (ROP) is another major issue for drilling contrac- tors. Low ROP (for example, 3 to 5 feet per hour) is primari- ly a result of the great compressive strength of highly overbur- dened formations. Initially, tri-cone bits with hardened inserts for drilling hard formations at shallower depths were applied as wells went deeper. However, at deeper depths it is more difficult to know when a tri- cone bit’s bearings have failed, a situa- tion that can occur more frequently when more weight is applied to the bit in a deep well. This can lead to timely fail- ures, lost cones, more frequent trips, higher costs, and lower overall ROP. The advantages of using a PDC bit and PDC hole opener include: • Better performance • Smoother drill operation • Integral design • No weld-on components • No moving parts A PDC drill bit can triple the rate of penetration due to extended hours of bit life, no moving components, and less wear and tear on rigs. In addition to the increased rate of penetration, the DDI Volcano PDC hole opener/reamer solves several other major issues HDD drilling contractors continually face: Loss of Cone Cutters Down Hole Cones are commonly lost from tri- cone reamers for a variety of reasons. Whether it’s poor construction of the tool, overuse, or other extenuating cir- cumstances, cone loss is a constant and looming threat which can be cata- strophic. When it occurs, the drilling company must fish out the lost cone, and in some cases, start the bore again from scratch. All of this is done at the cost of the drilling company. Since there are no moving components on the DDI Volcano PDC hole opener/reamer, there is nothing to break and fall off down hole. Fuel Usage A bit with a slow ROP lengthens the time a drilling company spends onsite. The longer a drilling company spends on a jobsite, and the more support vehicles are needed, fuel costs can soar to hundreds of thousands of dollars. Recent figures have shown 40-60% fuel savings whi le running the DDI Volcano PDC hole opener/reamer. The faster the ROP, the greater the fuel savings. Labor and Housing Costs Labor and housing costs follow the same logic as fuel usage. The longer a company spends on a job, the more their labor and housing costs. If a com- pany can shave days or weeks off a job, the savings are enormous. PDC bits and hole openers can be used in a variety of conditions without the fear of losing cones or parts in the hole. They can be custom manufactured and are available in a wide range of size and thread combinations to meet spe- cific project requirements. 1950s through 2013 technology Why use a thing of the past? DDI Volcano PDC hole openers are the future. Volcano ® PDC bit by DDI 2014-2015 technology Every American uses 40,000 pounds of minerals each year.