A new bit-frame combination proved to be the right concoction offshore.

Hughes Christensen did a little innovative work and came up with a solution that allowed the Cuulong Joint Venture Operating Co. to drill farther into soft granite that it had been able to drill in previous attempts.

Working with company representatives in the offshore Vietnam area, the company combined its UltraMax MX frame with metal sealed bearings, used a harder carbide grade and added an 81/2-in. HardRok cutting structure, MX-55DX three-cone bit design and went to work.

Cuulong granite is typically softer than other granites off the southeast coast of Vietnam, and the company wanted a design that would beat the existing 1,729-ft (527-m) record. It beat the old record with a run of 2,133 ft (650 m) in 42.5 hours for an average penetration rate of 50.2 ft (15.3 m) an hour.
Engineers credited the ability of the bit to drill in gauge, eliminating reaming and shortened gauge life for the record run. The company drilled the well with sea water, with 100% losses and a floating mud cap.
The drilling program also involved directional drilling and one long steering section in which the azimuth was turned 90°. At one point, the penetration rate jumped to 98 ft/hour while drilling a fracture. The companies used an Anadril mud motor in the well.

Jim Jacobsen, Hughes Christensen engineer, said the bit came out of the hole "in gauge" (exactly 81/2-in.) even after completing a 52? tangent section with the large azimuth change.
For the operator, drilling cost dropped to US $473.91 per meter on the record well from a high cost of $805.94 on a previous run with another bit.

Five runs with the other bit produced an average run of 1,581 ft (482 m) in 33.2 hours and a cost of $512.51 per meter, while three wells drilled with the new bit produced an average run of 1,883 ft (574 m) in 34.3 hours for an average cost of $464.19 per meter.

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