Abstract: The strength of casing shoe and the drilling window of next section depend on the depth of shallow casing running, which influences the wellbore structure and casing level. According to the features of formation in an oversea deepwater block, in order to increase the depth of shallow casing and simplify the wellbore structure, the weighted drilling fluid is used to replace sea water for pump & dump drilling. The pump & dump drilling program and critical parameters are analyzed, so as to provide a new idea and method for reducing cost and improving efficiency in deepwater drilling. As the study shows, pump & dump is a good technology to increase shallow casing depth and optimize wellbore structure, which can reduce about $10M for a deepwater well. It is suggested to apply this technology to the deepwater well of which the drillability is good and the increasing depth of shallow casing is no more than 300 m.