Method of changing well fluid
This patent describes a method of changing well fluid. It comprises: performing well drilling operations with a first drilling fluid and then setting casing; inserting around an inner tubular member which does not include drill bit attached to the lower end thereof an elastomeric annular wiper plug into an annular space between the well casing and the inner tubular member. The annular wiper plug having inner and outer ribs the outer ribs adapted to fit snugly into the well casing and the inner ribs adapted to fit snugly around the inner tubular member the annular space substantially filled with a first well fluid; circulating a second well fluid downwardly through the annular space between the casing and inner tubular member above the wiper plug. The wiper plug wiping the outside of the inner tubular member with the inner ribs and the inside of the casing with the outer ribs the wiper plug preventing the mixing of the first well fluid and the second well fluid; tripping out to attach a drill bit to the lower end of the inner tubular member, and tripping back in; and performing well drilling operations with the second well fluid.
- Assignee:
- Chevron Research Co., San Francisco, CA
- Patent Number(s):
- US 4893684; A
- Application Number:
- PPN: US 7-334019A
- OSTI ID:
- 6915917
- Country of Publication:
- United States
- Language:
- English
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