| 摘要 |
A wellbore assembly is provided that is operable in wellbores in the range o f six to six and one-half inches for obtaining large diameter cores, e.g., cores greater than or equal to two and seven-eighths inches in diameter. The wellbore assembly may preferably be utilized with drill pipe so that standard drilling rigs may be utilized in drilling and coring operations therewith. The drill pipe in accord with the present invention ma y be formed by modifying standard API drill pipe such as API four and one-half inch IF (Internal Flush) drill pipe in a special manner that renders the drill pipe still suitable fo r the type of drilling operations of interest and also suitable for handling by any drilling rig capable of using standard API drill pipe. Alternatively, the drill piper may be initially manufactured in accord with the specifications of the present invention. The coring tool preferably comprises an inner core barrel for receiving the core and, in a presently preferred embodiment, may be sized to obtain a core having an outer diameter from about three to three an d one-half inches.
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