| 摘要 |
A new induction logging tool has a toolstring length that is shorter than the toolstring length of the induction logging tool of the prior art. The new induction logging tool includes a new induction array which appears to be folded about an axis that coincides with the transmitter of the induction array of the prior art induction logging tool. The new folded induction array including a transmitter coil, located at an end of the new folded induction array, and a plurality of "cowound" receiver coils and bucking coils, a further plurality of individual receiver coils, and at least one further bucking coil located adjacent to and on one side of the transmitter coil of the new folded induction array. In the new folded induction array, each of the plurality of cowound receiver coils and bucking coils include a receiver coil (N-1) and a bucking coil (N), associated with another receiver coil (N), which are cowound together about the same bobbin, the receiver coil (N-1) and the bucking coil (N) being positioned at approximately the same distance from the transmitter coil. Each of the plurality of cowound receiver coils and bucking coils are formed by winding both the bucking coil (N) and the receiver coil (N-1) in a bifilar way on the same ceramic bobbin starting from the center of the bobbin and winding the receiver coil (N-1) and the bucking coil (N) in opposite outward directions.
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