Publications

Bit selection is one of the key elements in drilling optimization. The use of Polycrystalline Diamond Compact (PDC) bits in place of roller cone bits can improve drilling efficiency by increasing the rate of penetration and extending the useful life of the bit, thus lowering drilling costs.Since 1982 Virginia Indonesia Company (VICO), formerly Huffco Indonesia, has been testing PDC bits in the Kutei Basin of East Kalimantan.Initial tests were not encouraging, however recent developments in PDC bit technology have resulted in increased penetration rates, longer bit life and lower cost per foot drilling. Test results were obtained from development wells drilled in four separate fields and include 179 individual bit runs. Formations in which the tests have been run are deltaic, Upper to Middle Miocene sands and shales interbedded with coals and dolomitic stringers which range in depth from 2000 to 14,000. PDC bits have shown improvements over tri cone bits in both 12 1/4 and 8 1/2 hole sizes, in oil based and water-base muds.In the 12 1/4 hole size PDC bits compared to roller cone bits are saving 198 operating hours or $200,000 per well in the Nilam Field, 133 operating hours or $130,000 per well in the Badak Field, 130 operating hours or $163,000 per well in the Semberah Field and 105 hours or $100,000 per well in the Mutiara Field. In the 8 1/2 hole size the time savings is 58 operating hours or $70,000 per well in the Nilam Field and 105 operating hours or $112,000 per well in the Semberah Field.Other than time and cost savings, the use of PDC bits results in better hole stability and less hole enlargement. These hidden savings significantly affect the cement bond quality and minimize or eliminate zone communication problems and squeeze jobs.