This paper discusses a new double-effect protector (DEP). The serious wear of casing and drill pipe brings huge economic losses in drilling. On the basis of the traditional technology, a new DEP is designed, to reduce the wear of casing and drill pipe. The DEP's volume, which can be worn, increases 14% than the traditional protector's. As design and optimization by CAE software, the maximum stress, which is caused by the contacting collision&friction, is greatly lowered. As design and optimization by using CFD software, the fluid pressure loss of the DEP's annulus space, is decreased 17.5% than the traditional protector's. A new composite has been synthesized firstly, and has excellent mechanical performance, for example, abrasion resistant performance at high temperature. By using the Nonlinear Drillstring System Dynamics Simulation and Torque & Drag forecasting software, the study has been completed, which is about installed number and position of DEPs, for reducing wear on casing and friction on drill string in the typical deep well, and then the scheme, that the DEP is reasonably mounted, is applied while drilling. This document describes the first application of the DEP in X301 on Southwest oilfield, Sichuan, China. From the practice, the DEP's average working life has been enhanced 200 hours. Because of the use of the DEP, the wear of casing and drill pipe is effectively reduced, the quality of wellbore is improved, and the drilling period is shortened. The DEP and matching technology can provide effective technical support for deep well drilling and post-mining.

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