Snubbing stack
OwnerJaved Shahinventor
Life of this patent
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Abstract
A snubbing apparatus for a wellhead has a snubbing stack with a upper sealing element and a lower sealing element that seal between the elongate string and the snubbing stack. A string driver carried by the snubbing stack manipulates the elongate string through the upper and lower sealing elements. There is a source of inert liquid connected to the snubbing stack between the upper sealing element and the lower sealing element. A pressure sensor is connected to sense the pressure below the lower sealing element and is connected to provide a pressure signal to the source of inert liquid. The source of inert liquid is configured to pressurize the snubbing stack between the upper sealing element and the lower sealing element in response to the pressure signal.
Claims21
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.
A method of snubbing an elongate string into a wellbore having a wellhead, the method comprising the steps of:
- providing a snubbing stack having a upper sealing element and a lower sealing element,
- inserting the elongate string into the snubbing stack such that the top and lower sealing elements seal between the elongate string and the snubbing stack;
- driving the elongate string to move through the upper sealing element and the lower sealing element;
- sensing a wellhead pressure below the lower sealing element;
- injecting an inert fluid into the snubbing stack;
- and
- pressurizing the inert fluid within the snubbing stack based on the wellhead pressure.
Dependencies are inferred from the claim text.