This paper details the lessons learned in late 2007 and early 2008 whilst air drilling vertical gas wells in the Travis Peak formation of the western East Texas deep Bossier play in Amoroso Field and applying the lessons learned in the US to a deep appraisal well drilled in Northern China.

The deep Bossier represents one of the most active onshore plays in the United States. Deep Bossier wells are 14,000 ft (4,267m) to 16,000 ft (4,876m) deep and intersect shale and sandstone formations ranging between 2,000 ft (610m) and 3,000 ft (914m) thick. The Travis Peak is also known as ‘tragic peak’ during conventional drilling operations because the sandstone is hard and abrasive in nature, leading to extreme low rate of penetration (ROP). Air Drilling technology was utilized to increase the ROP through the formation at depths of 10,000 ft (3,047m) and greater. The deep exploration wells in the Daqing area of Northern China are drilled to depths of 20,000ft (6,095m) and greater in an attempt to explore the deep volcanic reservoir potential in the area.

In the US the 8-1/2-in hole size was drilled using air hammers and roller cone bits using straight air or nitrogen. Temperatures in the Travis Peal formation were reported to be above 300°F (148°C). Temperatures in Northern China were reported to be as high as 400°F (204°C) in the 12-1/4-in hole size.

The fit-for-purpose equipment needed for the air drilling sections of these wells comprised of air hammers capable of drilling in high temperatures, hammer bits with full diamond inserts, high-temperature float valves, air compressors, nitrogen production units, mist injection systems, and rotating control diverters.

The lessons learned in the US were applied to the well in China where similar results were encountered. The drive to enhance air drilling to extreme depths and high temperatures previously believed to be off limits proved to be successful in both parts of the world.

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