Methods, apparatus and systems for creating bismuth alloy plugs for abandoned wells
AssigneeSchlumberger Technology Corporation
InventorsTerizhandur S. Ramakrishnan, Quincy K. Elias, Hua Zhang, Youssef Magdy Abdou Mohamed Elkady, Yixuan Feng
Life of this patent
Estimating the term…
Abstract
A wellbore is plugged using a bismuth alloy. In one embodiment, the bismuth alloy comprises an alloy of bismuth and tin. In another embodiment, the bismuth alloy comprises an alloy of bismuth and silver. The wellbore can be arranged so that a liquid bismuth alloy sets with an excess pressure of the plug relative to the borehole fluid pressure along a desired seal height distance. Other aspects are described and claimed.
Claims9
A method for plugging a wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
- a) determining a measured depth in the wellbore corresponding to a portion of the formation that will interface to a plug when formed in situ;
- b) determining at least one property of the wellbore at the measured depth in the wellbore;
- and
- c) using the at least one property of the wellbore as determined in b) to select or rule out an alloy of bismuth and tin or an alloy of bismuth and silver for use in forming a plug in situ at the measured depth;
- and
- d) determining at least one additional parameter based on the at least one property of b), wherein the at least one additional parameter is used in c) to select or rule out the alloy of bismuth and tin or the alloy of bismuth and silver for use in forming the plug in situ at the measured depth, wherein the at least one additional parameter comprises a maximum allowed temperature at the measured depth in the wellbore, where the maximum allowed temperature is based on a boiling point of water at the pressure for the measured depth.
A method for plugging a wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
- a) determining a measured depth in the wellbore corresponding to a portion of the formation that will interface to a plug when formed in situ;
- b) determining at least one property of the wellbore at the measured depth in the wellbore, wherein the at least one property of b) comprises at least one property selected from the following:
- pH of wellbore fluid, temperature and pressure at the measured depth in the wellbore;
- and
- c) using the at least one property of the wellbore as determined in b) to select or rule out an alloy of bismuth and tin or an alloy of bismuth and silver for use in forming a plug in situ at the measured depth, wherein in c), if the pH of the wellbore fluid at the measured depth is less than a predetermined maximum pH value that is indicative of risk of corrosion to the alloy of bismuth and tin, then the alloy of bismuth and tin is ruled out and the alloy of bismuth and silver is selected for use in forming the plug in situ at the measured depth unless another criterion indicates otherwise.
Dependencies are inferred from the claim text.