Wellbore operations system and method
AssigneeSaudi Arabian Oil Company
InventorsGraham Hitchcock, Arthur Herman Hale
Life of this patent
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Abstract
A downhole operation in a wellbore having a lost circulation zone that includes plugging the lost circulation zone with a material that solidifies, and extracting a core from the solidified material to form a bore through the solidified material. The core is extracted with a monolithic coring bit, which retains the core within for removing the core from the wellbore. An example of a material that solidifies are eutectic alloys, such as an alloy of bismuth and tin. Such eutectic alloys have two properties that make them attractive for use in downhole applications. Namely, these alloys expand upon solidifying (rather than shrinking like other metals), and they have relatively low melting temperatures (138° C. to 170° C.).
Claims20
A method of operating in a wellbore comprising:
- forming a plug in a portion of the wellbore having a lost circulation zone;
- forming a core by excavating through the plug with an annular bit member that is configured so that the core has an outer diameter that ranges between around 75% to around 60% of an outer diameter of the plug within the wellbore;
- extracting the core from the plug to define an axial passage through the plug;
- and
- removing the core from the wellbore.
A system for use in a wellbore comprising:
- a string assembly comprising a pipe string;
- an annular bit member on an end of the pipe string comprising,
- an annular body having an outer diameter strategically dimensioned to be in sliding contact with an inner diameter of the wellbore,
- a cutting end on a downhole end of the body,
- an annulus formed axially through the body that selectively receives a core as the cutting end is in cutting engagement with the plug,
- a bore extending axially through the body having a diameter that ranges between about 60% to about 75% of a passable inner diameter of the wellbore, and
- a retaining system in selective retaining contact with the core inside the bit;
- and
- a drive system in selective rotational coupling with the string assembly.
Dependencies are inferred from the claim text.