In the actual logging process, in order to obtain multiple measurement parameters at the same time, multi instruments need to be hooked to perform combination logging. However, when logging of difficult wells, such as highly-deviated well, shoulder and dogleg with higher degree of horizontal well, it may be difficult for the instruments to run in the wells or even become stuck.

In order to ensure that the instrument string is smoothly lifted or lowered in the well, you must use SITAN knuckle joints among instrument strings, the flexibility of instrument string bending can enhance. This is beneficial for instrument passing through casing joint, or operating in highly-deviated well and horizontal well.

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