| 主权项 |
1. A snubbing apparatus for a wellbore having a wellhead, an elongate string being inserted into the wellbore through the wellhead, the snubbing apparatus comprising:
a snubbing stack having a upper sealing element and a lower sealing element, wherein, in operation, the upper and lower sealing elements seal between the elongate string and the snubbing stack; a string driver carried by the snubbing stack, the string driver manipulating the elongate string through the upper sealing element and the lower sealing element; a source of inert liquid connected to the snubbing stack between the upper sealing element and the lower sealing element; and a pressure sensor connected to sense the pressure below the lower sealing element and connected to provide a pressure signal to the source of inert liquid, the source of inert liquid being configured to pressurize the snubbing stack between the upper sealing element and the lower sealing element in response to the pressure signal. |
