Controlling lost circulation in flowing HP/HT wells: Case history

High-pressure/high-temperature (HP/HT) wells can present many challenges, including lost circulation, well kicks, underground blowouts, or other mechanical constraints, before a final target depth of 12,000 ft or deeper is reached. Thereafter, the bottomhole environment with temperatures greater than 300degreesF and pressures exceeding 10,000 psi tests the limits of hardware and chemicals. Each operational misjudgment or tool malfunction can affect the well costs significantly. This paper addresses a well-control issue in an HP/HT exploration well in which a possible underground crossflow was in progress and the well was losing oil-based mud.