Highly -deviated Three- target Directional Well Drilling Technology in Well Zhang 28

Well Zhang 28, the first highly-deviated well in Zhangdian area in Henan oilfield, is 3034m deep with a closure of 926m. Deviation angle of the well intervals in each target is 74.9°. Requirements for target-hitting accuracy are high and drilling operation is very complex. This paper introduces its geologic and enginccring designs and the tcchnological measures for well trajectory control,wellbore cleaning and downhole safety. They can be used for reference when drilling similar wells in this area.