Method for drilling and coring
A method of drilling boreholes enables a cylindrical solid core sample to be obtained from a formation. A coring bit together with a core barrel and concentrically arranged drill pipe provides central and annular passageways. The annular passageway is used for circulating fluid to the bit and back up the borehole annulus while the central passageway provides for the return of drilling fluid and cores. The circulating fluid is forced down through the drill-string annulus to the drill bit, and back up through the hole annulus to remove debris and cool the bit. The cores which have been cut by the bit are accumulated within the core barrel, and from time to time, the pressure of the drilling fluid is increased while the central passageway is opened to the flow of fluid, thereby forcing the fluid to flow into and up through the central passageway, carrying the accumulated cores. A predetermined pressure drop is maintained across the face of the diamond bit. (12 claims)
- Assignee:
- EDB-82-087559
- Patent Number(s):
- US 3578093
- OSTI ID:
- 5666721
- Country of Publication:
- United States
- Language:
- English
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