CASING DETECTION TOOLS AND METHODS

摘要

Methods and tools for detecting casing position downhole is presented. The method utilizes electromagnetic. (EM) tools with tilted antenna systems to detect casing position. Sometimes titled antenna designs also increase EM tools' sensitivity to formation parameters, which can lead to false signals for casing detection. In addition, it is very difficult to distinguish measured signals between a casing source and a formation source. The methods presented help to distinguish between the two sources more clearly. The methods and tools presented also help to minimize those environmental effects, as well as enhance the signals from a surrounding conductive casing. The methods herein provide ideas of EM tool's design to precisely determine casing position within a certain distance to casing position.

主权项

1. A downhole logging method that comprises:
obtaining formation resistivity measurements from a first borehole; determining an expected environmental signal level for a second borehole at a specified position relative to the first borehole, based at least in part on the formation resistivity measurements; selecting at least one of a transmitter-receiver spacing and an operating frequency to provide a desired detection signal level for the first borehole from the second borehole, the desired detection signal level being greater than the expected environmental signal level; and providing a tilted antenna logging tool having the selected spacing and/or operating frequency in a bottomhole assembly for the second borehole.