Trenchless Technology

NOV 2018

Trenchless Technology is the premier communications vehicle for the trenchless industry. Through our multiple platforms, readers receive insights into the trenchless industry, as well as keep connected to the latest news, products and projects.

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Page 53 of 68

field in the 1970s. Since then, the de- signs have changed dramatically to fit the various different drilling indus- tries, including HDD. In the correct for- mations, PDC bits are fast, durable, and steer easily. PDC bits have different de- signs that include different number of blades, different size cutters, and differ- ent blade angles. The more blades on a PDC bit, the harder the formation it can handle but the slower it cuts in softer formations. There are many formations and PSI that PDC bits work well in such as shale, sandstone, limestone, sand, and clay. The benefit to PDC bits is they also can work well in both soft and hard formations. Whereas, most rock bits are only designed for rock and the rate of penetration dramatically drops when in softer formations. PDC bits work well in rock with PSI between 2,000 to 30,000. Because they cut so fast, issues sometime arise when not enough fluid is being pumped to clear the cuttings out of the hole. When a PDC bit sits in its own cuttings, this can cause the bit to wear unevenly and prematurely fail, even in the correct formations. A mud motor or rod within a rod system is re- quired to run PDC bits. Always check with the manufacturer for recommend- ed RPMs, WOB, and GPM. W W W.T R E N C H L E S S T EC H N O LO GY.C O M 53 The air hammer system is the best system for extremely hard, abrasive rock. The air hammer system uses an air hammer, an air compressor, a hammer bit, and sometimes a support pack.

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