| 摘要 |
A tool for initiating a downhole function in a subsurface well, such as a cased well. The tool has memory adapted to store a well-specific reference pattern of one or more downhole well characteristics as a function of position along the well, one or more sensors responsive to the downhole well characteristics, and a clocked processor. The processor is adapted to receive well characteristic signals from the sensors, determine, from the signals and the reference pattern in memory, the position of the tool along the well, and automatically initiate a downhole function at a preprogrammed position along the well while the tool is moved at a substantially constant rate along the well. The tool may be configured in a string of tools for performing multiple downhole functions. In some embodiments the reference pattern is the known spacing of discrete downhole features, such as casing collars. In some other embodiments the reference pattern is a log of a geophysical parameter, such as a natural gamma log. Methods of use are also disclosed.
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