Abstract: Safe and efficient purging of residual fluid in coiled tubing can effectively reduce the load of the vehicle-borne roller after the completion of a coiled tubing operation and reduce the risks during long-distance transportation. Meanwhile, the risks of blocking and holding pressure caused by freezing of residual fluid in coiled tubing operation in winter can be avoided, which provides a reliable guarantee for the follow-up complex analysis of the coiled tubing in downhole operation. In order to realize the effective purging and the intrinsic safety of the equipment, a residual liquid purging device for coiled tubing was developed based on the design scheme of the linkage operation process between the diesel high pressure compressor and the gas storage tank. Through indoor and field tests, the performance parameters of the device, such as pressure at all levels, rotating speed, maximum working displacement, rated gas storage pressure, rated gas storage capacity and effective purging time, were verified and the performance and purging efficiency of the device were analyzed and evaluated. The development of the device provides a feasible method for the safe and efficient purging of the residual liquid in coiled tubing.

Key words: coiled tubing, residual liquid purging device, maximum working displacement, rated gas storage pressure, effective purging time